Underwriting Agreement, dated as of September 6, 2018, by and between Infinera Corporation and Morgan Stanley & Co. LLC, as manager of the underwriter named therein

Exhibit 10.1

$350,000,000

INFINERA CORPORATION

2.125% CONVERTIBLE SENIOR NOTES DUE 2024

UNDERWRITING AGREEMENT

September 6, 2018

September 6, 2018

To the Managers named in Schedule I hereto

for the Underwriters named in Schedule II hereto

Ladies and Gentlemen:

Infinera Corporation, a Delaware corporation (the “Company”), proposes to issue and sell to the several underwriters named in Schedule II hereto (the “Underwriters”), for whom you are acting as managers (the “Managers”), $350,000,000 principal amount of its 2.125% Convertible Senior Notes due 2024 (the “Firm Securities”), as set forth in Schedule I hereto and to be issued pursuant to the provisions of an indenture (the “Base Indenture”), as supplemented by a supplemental indenture (the Base Indenture, as so supplemented, the “Indenture”), in each case, to be dated as of September 11, 2018, between the Company and U.S. Bank National Association, as Trustee (the “Trustee”). The Company also proposes to issue and sell to the several Underwriters not more than an additional $52,500,000 aggregate principal amount of its 2.125% Convertible Senior Notes due 2024 (the “Additional Securities”) if and to the extent that you, as Managers, shall have determined to exercise, on behalf of the Underwriters, the right to purchase such Additional Securities granted to the Underwriters in Section 2 hereof, solely for the purpose of covering over-allotments made in connection with the offering of the Firm Securities. The Firm Securities and the Additional Securities are hereinafter collectively referred to as the “Securities”. The Company’s common stock, par value $0.001 per share, is hereinafter referred to as the “Common Stock.” The Securities will be convertible into cash, shares of Common Stock (the “Underlying Securities”) or a combination of cash and Underlying Securities, at the Company’s election. If the firm or firms listed in Schedule II hereto include only the Managers listed in Schedule I hereto, then the terms “Underwriters” and “Managers” as used herein shall each be deemed to refer to such firm or firms.

In connection with the offering of the Firm Securities, the Company is entering into capped call transactions with one or more of the Underwriters or their respective affiliates and/or other financial institutions (the “Option Counterparties”) pursuant to separate capped call transaction confirmations (the “Base Capped Call Confirmations”), to be dated the date hereof, and in connection with any exercise by the Underwriters of their option to purchase any Additional Securities, the Company and the Option Counterparties may enter into additional capped call transactions pursuant to additional capped call transaction confirmations (the “Additional Capped Call Confirmations”), to be dated the date on which the Underwriters exercise their option to purchase such Additional Securities. The Base Capped Call Confirmations and the Additional Capped Call Confirmations are referred to herein collectively as the “Capped Call Confirmations.”

The Company has filed with the Securities and Exchange Commission (the “Commission”) a registration statement, including a prospectus, (the file number of which is set forth in Schedule I hereto) on Form S-3, relating to securities (the “Shelf Securities”), including the Securities and the Underlying Securities, to be issued from time to time by the Company. The registration statement as amended to the date of this

Agreement, including the information (if any) deemed to be part of the registration statement at the time of effectiveness pursuant to Rule 430A or Rule 430B under the Securities Act of 1933, as amended (the “Securities Act”), is hereinafter referred to as the “Registration Statement,” and the related prospectus covering the Shelf Securities dated September 5, 2018 in the form first used to confirm sales of the Securities (or in the form first made available to the Underwriters by the Company to meet requests of purchasers pursuant to Rule 173 under the Securities Act) is hereinafter referred to as the “Basic Prospectus.” The Basic Prospectus, as supplemented by the prospectus supplement specifically relating to the Securities in the form first used to confirm sales of the Securities (or in the form first made available to the Underwriters by the Company to meet requests of purchasers pursuant to Rule 173 under the Securities Act) is hereinafter referred to as the “Prospectus.” The term “preliminary prospectus” means any preliminary form of the Prospectus. For purposes of this Agreement, “free writing prospectus” has the meaning set forth in Rule 405 under the Securities Act, “Time of Sale Prospectus” means the documents and pricing information set forth opposite the caption “Time of Sale Prospectus” in Schedule I hereto, and “broadly available road show” means a “bona fide electronic road show” as defined in Rule 433(h)(5) under the Securities Act that has been made available without restriction to any person. As used herein, the terms “Registration Statement,” “Basic Prospectus,” “preliminary prospectus,” “Time of Sale Prospectus” and “Prospectus” shall include the documents, if any, incorporated by reference therein on the date hereof. The terms “supplement,” “amendment,” and “amend” as used herein with respect to the Registration Statement, the Basic Prospectus, the Time of Sale Prospectus, any preliminary prospectus or the Prospectus shall include all documents subsequently filed by the Company with the Commission pursuant to the Securities Exchange Act of 1934, as amended (the “Exchange Act”), that are deemed to be incorporated by reference therein.

1. Representations and Warranties. The Company represents and warrants to and agrees with each of the Underwriters that:

(a) The Registration Statement has become effective; no stop order suspending the effectiveness of the Registration Statement is in effect, and no proceedings for such purpose are pending before or threatened by the Commission. The Company is a well-known seasoned issuer (as defined in Rule 405 under the Securities Act) eligible to use the Registration Statement as an automatic shelf registration statement and the Company has not received notice that the Commission objects to the use of the Registration Statement as an automatic shelf registration statement.

(b) (i) Each document, if any, filed or to be filed pursuant to the Exchange Act and incorporated by reference in the Time of Sale Prospectus or the Prospectus complied or will comply when so filed in all material respects with the Exchange Act and the applicable rules and regulations of the Commission thereunder, (ii) each part of the Registration Statement, when such part became effective, did not contain, and each such part, as amended or supplemented, if applicable, will not contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements

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therein not misleading, (iii) the Registration Statement as of the date hereof does not contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading, (iv) the Registration Statement and the Prospectus comply, and as amended or supplemented, if applicable, will comply in all material respects with the Securities Act and the applicable rules and regulations of the Commission thereunder, (v) the Time of Sale Prospectus does not, and at the time of each sale of the Securities in connection with the offering when the Prospectus is not yet available to prospective purchasers and at the Closing Date (as defined in Section 4), the Time of Sale Prospectus, as then amended or supplemented by the Company, if applicable, will not, contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading, (vi) each other free writing prospectus identified in Schedule I hereto and each broadly available road show, if any, when considered together with the Time of Sale Prospectus, does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading and (vii) the Prospectus does not contain and, as amended or supplemented, if applicable, will not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading, except that the representations and warranties set forth in this paragraph do not apply to (A) statements or omissions in the Registration Statement, the Time of Sale Prospectus or the Prospectus based upon information relating to any Underwriter furnished to the Company in writing by such Underwriter through the Managers expressly for use therein or (B) that part of the Registration Statement that constitutes the Statement of Eligibility (Form T-1) under the Trust Indenture Act of 1939, as amended (the “Trust Indenture Act”), of the Trustee.

(c) The Company is not an “ineligible issuer” in connection with the offering pursuant to Rules 164, 405 and 433 under the Securities Act. Any free writing prospectus that the Company is required to file pursuant to Rule 433(d) under the Securities Act has been, or will be, filed with the Commission in accordance with the requirements of the Securities Act and the applicable rules and regulations of the Commission thereunder. Each free writing prospectus that the Company has filed, or is required to file, pursuant to Rule 433(d) under the Securities Act or that was prepared by or on behalf of or used or referred to by the Company complies or will comply in all material respects with the requirements of the Securities Act and the applicable rules and regulations of the Commission thereunder. Except for the free writing prospectuses, if any, identified in Schedule I hereto, and electronic road shows furnished to the Managers before first use, the Company has not prepared, used or referred to, and will not, without the Managers’ prior consent, prepare, use or refer to, any free writing prospectus.

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(d) The Company has been duly incorporated, is validly existing as a corporation in good standing under the laws of the jurisdiction of its incorporation, has the corporate power and authority to own its property and to conduct its business as described in the Time of Sale Prospectus and is duly qualified to transact business and is in good standing in each jurisdiction in which the conduct of its business or its ownership or leasing of property requires such qualification, except to the extent that the failure to be so qualified or be in good standing would not have a material adverse effect on the condition, financial or otherwise, or on the earnings, business or operations of the Company and its subsidiaries, taken as a whole (a “Material Adverse Effect”).

(e) Each subsidiary of the Company has been duly incorporated, is validly existing in good standing (which concept shall include the functional equivalent of “good standing” in non-U.S. jurisdictions, to the extent applicable) under the laws of the jurisdiction of its organization, has the corporate power and authority (or similar company or partnership power and authority) to own its property and to conduct its business as described in the Time of Sale Prospectus and is duly qualified to transact business and is in good standing in each jurisdiction in which the conduct of its business or its ownership or leasing of property requires such qualification, except to the extent that the failure to be so qualified or be in good standing would not have a Material Adverse Effect; all of the issued shares of capital stock (or equivalent equity interests, as applicable) of each subsidiary of the Company have been duly and validly authorized and issued, are fully paid and non-assessable and are owned directly by the Company, free and clear of all liens, encumbrances, equities or claims, except to the extent directors’ qualifying shares are required by law.

(f) This Agreement has been duly authorized, executed and delivered by the Company.

(g) The authorized capital stock of the Company conforms in all material respects as to legal matters to the description thereof contained in each of the Time of Sale Prospectus and the Prospectus.

(h) The shares of Common Stock outstanding as of the date hereof have been duly authorized and are validly issued, fully paid and non-assessable.

(i) Reserved.

(j) The Securities have been duly authorized and, when executed and authenticated in accordance with the provisions of the Indenture and delivered to and paid for by the Underwriters in accordance with the terms of this Agreement, will be valid and binding obligations of the Company, enforceable in accordance with their terms, subject to applicable bankruptcy, insolvency and similar laws affecting creditors’ rights generally and equitable principles of general applicability (the “Enforceability Exceptions”) and will be entitled to the benefits of the Indenture pursuant to which such Securities are to be issued, and the Securities and the Indenture will conform in all material respects to the descriptions thereof in each of the Time of Sale Prospectus and the Final Prospectus.

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(k) The maximum number of Underlying Securities initially issuable upon conversion of the Securities (assuming the Company elects to issue and deliver solely Underlying Securities in respect of all conversions and including the maximum number of Underlying Securities that may be issued upon conversion of the Securities in connection with a “Make-Whole Fundamental Change”, as such term is defined in the Indenture) (the “Maximum Number of Underlying Securities”) have been duly authorized and reserved for issuance upon such conversion and, when and to the extent issued upon conversion of the Securities in accordance with the terms of the Securities and the Indenture, will be validly issued, fully paid and non-assessable, and the issuance of the Maximum Number of Underlying Securities will not be subject to any preemptive or similar rights.

(l) On the Closing Date, the Indenture will have been duly qualified under the Trust Indenture Act and duly authorized, executed and delivered by the Company, and assuming due authorization, execution and delivery by the Trustee, will be a valid and binding agreement of, the Company, enforceable in accordance with its terms, subject to the Enforceability Exceptions.

(m) The execution and delivery by the Company of, and the performance by the Company of its obligations under, this Agreement, the Indenture and the Securities (together, the “Transaction Documents”) and the Capped Call Confirmations will not contravene any provision of or constitute a default under (i) applicable law, (ii) the certificate of incorporation or by-laws of the Company, (iii) any agreement or other instrument binding upon the Company or any of its subsidiaries that is material to the Company and its subsidiaries, taken as a whole, or (iv) any judgment, order or decree of any governmental body, agency or court having jurisdiction over the Company or any subsidiary, except, in the cases of clauses (i), (iii) and (iv) above, as would not reasonably be expected to have a Material Adverse Effect or a material adverse effect on the Company’s ability to perform its obligations under the Transaction Documents or on its ability to consummate the transactions contemplated herein, and no consent, approval, authorization or order of, or qualification with, any governmental body or agency is required for the performance by the Company of its obligations under the Transaction Documents, except for those that have been, or will have been prior to the Closing Date, obtained, and such as may be required by the securities or Blue Sky laws of the various states in connection with the offer and sale of the Securities, and except where the failure to obtain such consents, individually or in the aggregate, would not reasonably be expected to have a Material Adverse Effect or a material adverse effect on the Company’s ability to conduct the offering of the Securities.

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(n) There has not occurred any material adverse change, or any development that would reasonably be expected to cause a prospective material adverse change, in the condition, financial or otherwise, or in the earnings, business or operations of the Company and its subsidiaries, taken as a whole, from that set forth in the Time of Sale Prospectus.

(o) Other than as set forth in the Time of Sale Prospectus, (i) there are no legal or governmental proceedings pending to which the Company or any of its subsidiaries is a party or to which any of the properties of the Company or any of its subsidiaries is subject that would individually or in the aggregate reasonably be expected to have a Material Adverse Effect or a material adverse effect on the power or ability of the Company to perform its obligations under the Transaction Documents or to consummate the transactions contemplated herein or therein; and (ii) to the Company’s knowledge, no such proceedings are threatened. There are no such proceedings that are required to be described in the Registration Statement or the Prospectus that are not so described and there are no statutes, regulations, contracts or other documents that are required to be described in the Registration Statement or the Prospectus or to be filed as exhibits to the Registration Statement that are not described or filed as required.

(p) The Company and its subsidiaries own or possess or can obtain on commercially reasonable terms adequate rights to use all patents, patent applications, trademarks, service marks, trade names, trademark registrations, service mark registrations, copyrights, licenses, know-how (including trade secrets and other unpatented and/or unpatentable proprietary or confidential information, systems or procedures) and other intellectual property (“Intellectual Property”) necessary for the conduct of their respective businesses as described in the Time of Sale Prospectus, except where the failure to so own, possess or acquire such rights would not reasonably be expected to have a Material Adverse Effect, and except as described in the Time of Sale Prospectus, the Company and its subsidiaries have not received any notice of any claim of infringement, misappropriation or violation of or conflict with any such rights of others that, singly or in the aggregate would reasonably be expected to have a Material Adverse Effect. The Company and its subsidiaries have taken reasonable steps in accordance with normal industry practice to maintain the confidentiality of all Intellectual Property of the Company and its subsidiary that is material to the business or operation of the Company or any subsidiary and the value of which to the Company or any subsidiary is contingent upon maintaining the confidentiality thereof, and none of such Intellectual Property has been disclosed other than to employees, representatives and agents of the Company or any subsidiary, all of whom are bound by written confidentiality agreements.

(q) The Company and its subsidiaries (i) are in compliance with any and all applicable foreign, federal, state and local laws and regulations relating to the protection of human health and safety, the environment or hazardous or toxic substances or wastes, pollutants or contaminants (“Environmental Laws”), (ii) have received all permits, licenses or other approvals required of them under applicable Environmental Laws to conduct their respective businesses and (iii) are in compliance with all terms and conditions of any such permit, license or

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approval, except where such noncompliance with Environmental Laws, failure to receive required permits, licenses or other approvals or failure to comply with the terms and conditions of such permits, licenses or approvals would not, singly or in the aggregate, reasonably be expected to have a Material Adverse Effect.

(r) There are no costs or liabilities associated with Environmental Laws (including, without limitation, any capital or operating expenditures required for clean-up, closure of properties or compliance with Environmental Laws or any permit, license or approval, any related constraints on operating activities and any potential liabilities to third parties) which would, singly or in the aggregate, reasonably be expected to have a Material Adverse Effect.

(s) Except as described in the Time of Sale Prospectus, (a) there are no proceedings that are pending, or that are known to be contemplated, against the Company or any of its subsidiaries under any Environmental Laws in which a governmental entity is also a party, other than such proceedings regarding which it is reasonably believed no monetary sanctions of $100,000 or more will be imposed, (b) the Company and its subsidiaries are not aware of any facts or issues regarding compliance with Environmental Laws, or liabilities or other obligations under Environmental Laws, that could reasonably be expected to have a material effect on the capital expenditures, earnings or competitive position of the Company and its subsidiaries, and (c) none of the Company and its subsidiaries anticipates material capital expenditures relating to any Environmental Laws.

(t) The Company is not, and after giving effect to the transactions contemplated by the Capped Call Confirmations, the offering and sale of the Securities and the application of the proceeds thereof as described in the Time of Sale Prospectus and the Prospectus will not be, required to register as an “investment company” as such term is defined in the Investment Company Act of 1940, as amended (the “Investment Company Act”).

(u) Each preliminary prospectus filed as part of the Registration Statement as originally filed or as part of any amendment thereto, or filed pursuant to Rule 424 under the Securities Act, complied when so filed in all material respects with the Securities Act and the applicable rules and regulations of the Commission thereunder.

(v) (i) Neither the Company nor any of its subsidiaries, nor any director, officer, or employee, nor, to the Company’s knowledge, any affiliate, agent or representative of the Company or of any of its subsidiaries or affiliates, has taken any action in furtherance of an offer, payment, promise to pay, or authorization or approval of the payment, giving or receipt of money, property, gifts or anything else of value, directly or indirectly, to any “government official” (including any officer or employee of a government or government-owned or controlled entity or of a public international organization, or any person acting in an official capacity for or on behalf of any of the foregoing, or any political party or party official or candidate for political office) in order to influence official

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action, or to any person in violation of any applicable anti-corruption laws; (ii) the Company and its subsidiaries and affiliates have conducted their businesses in compliance with applicable anti-corruption laws and have instituted and maintained and will continue to maintain policies and procedures reasonably designed to promote and achieve compliance with such laws and with the representations and warranties contained herein; and (iii) neither the Company nor its subsidiaries will use, directly or indirectly, the proceeds of the offering in furtherance of an offer, payment, promise to pay, or authorization of the payment or giving of money, or anything else of value, to any person in violation of any applicable anti-corruption laws.

(w) The operations of the Company and its subsidiaries are and have been conducted at all times in material compliance with all applicable financial recordkeeping and reporting requirements, including those of the Bank Secrecy Act, as amended by Title III of the Uniting and Strengthening America by Providing Appropriate Tools Required to Intercept and Obstruct Terrorism Act of 2001 (USA PATRIOT Act), and the applicable anti-money laundering statutes of jurisdictions where the Company and its subsidiaries conduct business, the rules and regulations thereunder and any related or similar rules, regulations or guidelines, issued, administered or enforced by any governmental agency (collectively, the “Anti-Money Laundering Laws”), and no action, suit or proceeding by or before any court or governmental agency, authority or body or any arbitrator involving the Company or any of its subsidiaries with respect to the Anti-Money Laundering Laws is pending or, to the knowledge of the Company, threatened.

(x) (i) Neither the Company, nor any of its subsidiaries, nor any director, officer, or employee thereof, nor, to the Company’s knowledge, any agent, affiliate or representative of the Company or any of its subsidiaries, is an individual or entity (“Person”) that is, or is owned or controlled by one or more Persons that are:

(A) the subject of any sanctions administered or enforced by the U.S. Department of Treasury’s Office of Foreign Assets Control (“OFAC”), the United Nations Security Council (“UNSC”), the European Union (“EU”), Her Majesty’s Treasury (“HMT”), or other relevant sanctions authority (collectively, “Sanctions”), or

(B) located, organized or resident in a country or territory that is the subject of Sanctions (including, without limitation, Crimea, Cuba, Iran, North Korea and Syria).

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(ii) The Company will not, directly or indirectly, use the proceeds of the offering, or lend, contribute or otherwise make available such proceeds to any subsidiary, joint venture partner or other Person:

(A) to fund or facilitate any activities or business of or with any Person or in any country or territory that, at the time of such funding or facilitation, is the subject of Sanctions; or

(B) in any other manner that will result in a violation of Sanctions by any Person (including any Person participating in the offering, whether as underwriter, advisor, investor or otherwise).

(iii) For the past 5 years, the Company and its subsidiaries have not knowingly engaged in, are not now knowingly engaged in, and will not engage in, any dealings or transactions with any Person, or in any country or territory, that at the time of the dealing or transaction is or was the subject of Sanctions.

(y) The Company and each of its subsidiaries have filed all federal, state, local and foreign tax returns required to be filed through the date of this Agreement or have requested extensions thereof (except where the failure to file would not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect) and have paid all taxes required to be paid thereon (except for cases in which the failure to file or pay would, individually or in the aggregate, not have a Material Adverse Effect, or, except as currently being contested in good faith and for which reserves required by U.S. GAAP have been created in the financial statements of the Company), and no tax deficiency has been determined adversely to the Company or any of its subsidiaries which has had (nor does the Company nor any of its subsidiaries have any notice or knowledge of any tax deficiency which could reasonably be expected to be determined adversely to the Company or its subsidiaries and which could, individually or in the aggregate, reasonably be expected to have) a Material Adverse Effect.

(z) The Company and each of its subsidiaries maintain a system of internal accounting controls sufficient to provide reasonable assurance that (i) transactions are executed in accordance with management’s general or specific authorizations; (ii) transactions are recorded as necessary to permit preparation of financial statements in conformity with generally accepted accounting principles and to maintain asset accountability; (iii) access to assets is permitted only in accordance with management’s general or specific authorization; (iv) the recorded accountability for assets is compared with the existing assets at reasonable intervals and appropriate action is taken with respect to any differences; and (v) the interactive data in eXtensible Business Reporting Language (“XBRL”) included or incorporated by reference in the Registration Statement is accurate. Except as described in the Time of Sale Prospectus, since the end of the Company’s most recent audited fiscal year, there has been (i) no material weakness in the Company’s internal control over financial reporting (whether or not remediated) and (ii) no change in the Company’s internal control over financial reporting that has materially affected, or is reasonably likely to materially affect, the Company’s internal control over financial reporting.

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(aa) The interactive data in XBRL included or incorporated by reference in the Registration Statement fairly presents the information called for in all material respects and has been prepared in accordance with the Commission’s rules and guidelines applicable thereto.

(bb) The financial statements, together with the related schedules and notes, included in the Time of Sale Prospectus present fairly in all material respects the consolidated financial position of the entities to which they relate as of and at the dates indicated and the results of their operations and cash flows for the periods specified. Such financial statements have been prepared in all material respects in accordance with generally accepted accounting principles in the United States applied on a consistent basis throughout the periods involved, except as may be expressly stated in the related notes thereto. The financial data set forth in the Time of Sale Prospectus under the captions “Summary Historical Consolidated and Pro Forma Financial and Other Financial Data of Infinera” and “Summary Historical Consolidated Financial Data of Coriant” fairly present in all material respects the information set forth therein on a basis consistent with that of the audited financial statements contained in the Time of Sale Prospectus. The unaudited pro forma condensed combined financial statements of the Company and its subsidiaries and the related notes thereto included under the caption “Unaudited Pro Forma Condensed Combined Financial Information,” and elsewhere in the Time of Sale Prospectus present fairly in all material respects the information contained therein, have been prepared in accordance with the Commission’s rules and guidelines with respect to pro forma financial statements (except that, in accordance with the relief granted by the Commission pursuant to its letter to the Company dated August 31, 2018, such unaudited pro forma condensed combined financial statements do not include an unaudited pro forma condensed combined statement of operations for the six months ended June 30, 2018) and have been properly presented on the bases described therein, and the assumptions used in the preparation thereof are reasonable and the adjustments used therein are appropriate to give effect to the transaction and circumstances referred to therein. The statistical and market related data and forward looking statements included in the Time of Sale Prospectus are based on or derived from sources that the Company believes to be reliable and accurate in all material respects and represent their good faith estimates that are made on the basis of data derived from such sources.

(cc) Ernst & Young LLP who have certified certain financial statements of the Company and its subsidiaries, and have audited the Company’s internal control over financial reporting are independent registered public accountants as required by the Securities Act and the rules and regulations of the Commission thereunder.

(dd) BDO USA, LLP who have certified certain financial statements of Telecom Holding Parent LLC and its subsidiaries are independent registered public accountants as required by the Securities Act and the rules and regulations of the Commission thereunder.

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(ee) PricewaterhouseCoopers, LLP who have certified certain financial statements of Telecom Holding Parent LLC and its subsidiaries are independent accountants under Rule 101 of the Code of Professional Conduct of the American Institute of Certified Public Accountants, and its rulings and interpretations.

(ff) The Company does not have knowledge of any event or circumstance that would reasonably cause the Coriant Transaction (defined below) to not be consummated substantially in accordance with the terms of the Unit Purchase Agreement (the “Purchase Agreement”), dated as of July 23, 2018, among the Company and Coriant Investor LLC (the “Seller”) and Oaktree Optical Holdings, L.P. (the “Lender”) (such transaction, the “Coriant Transaction”) and as described in the Time of Sale Prospectus. To the Company’s knowledge, each representation and warranty of the Seller and the Lender contained in the Purchase Agreement is true and correct as of the date hereof (except for representations and warranties made as of a specific date, which shall be true and correct as of such date), in each case except where the failure of any such representation or warranty to be true and correct would not have, individually or in the aggregate, a material adverse effect on the condition, financial or otherwise, or on the earnings, business or operations of the Seller and its subsidiaries, taken as a whole, or the ability of Seller or Lender to consummate the Coriant Transaction substantially in accordance with the terms of the Purchase Agreement and as described in the Time of Sale Prospectus.

2. Agreements to Sell and Purchase. The Company hereby agrees to sell to the several Underwriters, and each Underwriter, upon the basis of the representations and warranties herein contained, but subject to the conditions hereinafter stated, agrees, severally and not jointly, to purchase from the Company the respective principal amount of Firm Securities set forth in Schedule II hereto opposite its name at the purchase price set forth in Schedule I hereto (the “Purchase Price”) plus accrued interest, if any, from September 6, 2018 to the Closing Date.

On the basis of the representations and warranties contained in this Agreement, and subject to its terms and conditions, the Company agrees to sell to the Underwriters, and the Underwriters shall have the right to purchase, severally and not jointly, up to $52,500,000 aggregate principal amount of Additional Securities, at the Purchase Price plus accrued interest, if any, to the date of payment and delivery, solely to cover overallotments. The Managers may exercise this right on behalf of the Underwriters in whole or from time to time in part by giving written notice to the Company not later than 30 days after the date of this Agreement. Any exercise notice shall specify the principal amount of Additional Securities to be purchased by the Underwriters and the date on which such Additional Securities are to be purchased. Each purchase date must be at least one business day after the written notice is given, unless waived by the Company in writing, and may not be earlier than the Closing Date nor later than ten business days after the date of such notice. Additional Securities may be purchased as provided in Section 4 solely for the purpose of covering sales of securities in excess of the number of the Firm Securities. On each day, if any, that Additional Securities are to be purchased (an “Option Closing Date”), each Underwriter agrees, severally and not jointly, to

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purchase the principal amount of Additional Securities (subject to such adjustments to eliminate denominations of less than $1,000 as the Managers may determine) that bears the same proportion to the total principal amount of Additional Securities to be purchased on such Option Closing Date as the principal amount of Firm Securities set forth in Schedule II hereto opposite the name of such Underwriter bears to the total principal amount of Firm Securities.

3. Public Offering. The Company is advised by the Managers that the Underwriters propose to make a public offering of their respective portions of the Securities as soon after the Registration Statement and this Agreement have become effective as in their judgment is advisable. The Company is further advised by the Managers that the Securities are to be offered to the public upon the terms set forth in the Prospectus.

4. Payment and Delivery. Payment for the Firm Securities shall be made to the Company in Federal or other funds immediately available in New York City against delivery of such Firm Securities for the respective accounts of the several Underwriters on the closing date and time set forth in Schedule I hereto, or at such other time on the same or such other date, not later than the fifth business day thereafter, as may be mutually agreed in writing by the Company and the Managers. The time and date of such payment are hereinafter referred to as the “Closing Date.”

Payment for any Additional Securities shall be made to the Company in Federal or other funds immediately available in New York City against delivery of such Additional Securities for the respective accounts of the several Underwriters on the date and time specified in the corresponding notice described in Section 2 or at such other time on the same or on such other date, in any event not later than the second business day thereafter, as may be designated in writing by the Managers.

The Firm Securities and the Additional Securities shall be in definitive form or global form, as specified by the Managers, and registered in such names and in such denominations as the Managers shall request in writing not later than one full business day prior to the Closing Date or the applicable Option Closing Date, as the case may be. The Firm Securities and the Additional Securities shall be delivered to the Managers on the Closing Date or an Option Closing Date, as the case may be, for the respective accounts of the several Underwriters, with any transfer taxes payable in connection with the transfer of the Securities to the Underwriters duly paid, against payment of the Purchase Price therefor.

5. Conditions to the Underwriters’ Obligations. The several obligations of the Underwriters to purchase and pay for the Firm Securities on the Closing Date are subject to the following conditions:

(a) Subsequent to the execution and delivery of this Agreement and prior to the Closing Date:

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(i) there shall not have occurred any downgrading, nor shall any notice have been given of any intended or potential downgrading or of any review for a possible change that does not indicate the direction of the possible change, in the rating accorded any of the securities of the Company or any of its subsidiaries by any “nationally recognized statistical rating organization,” as such term is defined in Section 3(a)(62) of the Exchange Act; and

(ii) there shall not have occurred any change, or any development involving a prospective change, in the condition, financial or otherwise, or in the earnings, business or operations of the Company and its subsidiaries, taken as a whole, from that set forth in the Time of Sale Prospectus that, in the Managers’ judgment, is material and adverse and that makes it, in the Managers’ judgment, impracticable to market the Securities on the terms and in the manner contemplated in the Time of Sale Prospectus.

(b) The Underwriters shall have received on the Closing Date a certificate, dated the Closing Date and signed by an executive officer of the Company, to the effect set forth in Section 5(a)(i) above and to the effect that (i) the representations and warranties of the Company contained in this Agreement are true and correct as of the Closing Date with the same effect as if made on such delivery date, and (ii) the Company has complied with all of the agreements and satisfied all of the conditions on its part to be performed or satisfied hereunder on or before the Closing Date.

The officer signing and delivering such certificate may rely upon the best of his or her knowledge as to proceedings threatened.

(c) The Underwriters shall have received on the Closing Date an opinion and negative assurance statement of Wilson Sonsini Goodrich & Rosati, Professional Corporation, outside counsel for the Company, dated the Closing Date, to the effect set forth in Exhibit A. Such opinion shall be rendered to the Underwriters at the request of the Company and shall so state therein.

(d) The Underwriters shall have received on the Closing Date an opinion and negative assurance statement of Davis Polk & Wardwell LLP, counsel for the Underwriters, dated the Closing Date, in form and substance satisfactory to the Managers.

(e) The Underwriters shall have received, on each of the date hereof and the Closing Date, a letter dated the date hereof or the Closing Date, as the case may be, in form and substance satisfactory to the Underwriters, from Ernst & Young LLP, independent registered public accountants for the Company, containing statements and information of the type ordinarily included in accountants’ “comfort letters” to underwriters with respect to the financial statements and certain financial information contained in or incorporated by reference into the Registration Statement, the Time of Sale Prospectus and the Prospectus; provided that the letter delivered on the Closing Date shall use a “cut-off date” not earlier than the date hereof.

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(f) The Underwriters shall have received, on each of the date hereof and the Closing Date, a letter dated the date hereof or the Closing Date, as the case may be, in form and substance satisfactory to the Underwriters, from BDO USA, LLC, independent registered public accountants for Telecom Holding Parent LLC, containing statements and information of the type ordinarily included in accountants’ “comfort letters” to underwriters with respect to the financial statements and certain financial information contained in or incorporated by reference into the Registration Statement, the Time of Sale Prospectus and the Prospectus; provided that the letter delivered on the Closing Date shall use a “cut-off date” not earlier than the date hereof.

(g) The Underwriters shall have received, on each of the date hereof and the Closing Date, a letter dated the date hereof or the Closing Date, as the case may be, in form and substance satisfactory to the Underwriters, from PricewaterhouseCoopers, LLC, independent accountants for Telecom Holding Parent LLC, containing statements and information of the type ordinarily included in accountants’ “comfort letters” to underwriters with respect to the financial statements and certain financial information contained in or incorporated by reference into the Registration Statement, the Time of Sale Prospectus and the Prospectus.

(h) The Underwriters shall have received, on each of the date hereof and the Closing Date, a certificate signed by the Chief Financial Officer of the Company, dated respectively as of the date hereof and as of the Closing Date, to the effect set forth in Exhibit C.

(i) The “lock-up” agreements, each substantially in the form of Exhibit B hereto, between the Managers and each of the officers and directors of the Company and the other parties named in Schedule III hereto relating to sales and certain other dispositions of shares of common stock or certain other securities, delivered to the Managers on or before the date hereof, shall be in full force and effect on the Closing Date.

(j) The Maximum Number of Underlying Securities have been approved for listing, subject to notice of issuance, on The NASDAQ Global Select Market (the “NASDAQ”), and evidence thereof shall have been provided to the Managers.

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(k) The several obligations of the Underwriters to purchase Additional Securities hereunder are subject to the delivery to the Managers on the applicable Option Closing Date of the following:

(i) a certificate, dated the Option Closing Date and signed by an executive officer of the Company, confirming that the certificate delivered on the Closing Date pursuant to Section 5(b) hereof remains true and correct as of such Option Closing Date;

(ii) an opinion and negative assurance statement of Wilson Sonsini Goodrich & Rosati, Professional Corporation, outside counsel for the Company, dated the Option Closing Date, relating to the Additional Securities to be purchased on such Option Closing Date and otherwise to the same effect as the opinion required by Section 5(c) hereof;

(iii) an opinion and negative assurance statement of Davis Polk & Wardwell LLP, counsel for the Underwriters, dated the Option Closing Date, relating to the Additional Securities to be purchased on such Option Closing Date and otherwise to the same effect as the opinion required by Section 5(d) hereof;

(iv) a letter dated the Option Closing Date, in form and substance satisfactory to the Underwriters, from Ernst & Young LLP, independent registered public accountants for the Company, substantially in the same form and substance as the letter furnished to the Underwriters pursuant to Section 5(e) hereof; provided that the letter delivered on the Option Closing Date shall use a “cut-off date” not earlier than three business days prior to such Option Closing Date;

(v) a letter dated the dated the Option Closing Date, in form and substance satisfactory to the Underwriters, from BDO USA, LLC, independent registered public accountants for Telecom Holding Parent LLC, substantially in the same form and substance as the letter furnished to the Underwriters pursuant to Section 5(f) hereof; provided that the letter delivered on the Option Closing Date shall use a “cut-off date” not earlier than three business days prior to such Option Closing Date;

(vi) a letter dated the dated the Option Closing Date, in form and substance satisfactory to the Underwriters, from Pricewaterhouse Coopers, LLC, independent accountants for Telecom Holding Parent LLC, substantially in the same form and substance as the letter furnished to the Underwriters pursuant to Section 5(g) hereof;

(vii) a certificate, dated the Option Closing Date and signed by the Chief Financial Officer of the Company, substantially in the same form and substance as the letter furnished to the Underwriters pursuant to Section 5(h) hereof; and

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(ix) such other documents as you may reasonably request with respect to the good standing of the Company, the due authorization and issuance of the Additional Securities to be sold on such Option Closing Date and other matters related to the issuance of such Additional Securities.

6. Covenants of the Company. The Company covenants with each Underwriter as follows:

(a) To furnish to the Managers, without charge, a signed copy of the Registration Statement (including exhibits thereto and documents incorporated by reference therein) and to deliver to each of the Underwriters during the period mentioned in Section 6(e) or 6(f) below, as many copies of the Time of Sale Prospectus, the Prospectus, any documents incorporated by reference therein and any supplements and amendments thereto or to the Registration Statement as the Managers may reasonably request.

(b) Before amending or supplementing the Registration Statement, the Time of Sale Prospectus or the Prospectus, to furnish to the Managers a copy of each such proposed amendment or supplement and not to file any such proposed amendment or supplement to which the Managers reasonably object, except as may be required to comply with its obligations under the Exchange Act or other applicable law based on the advice of counsel.

(c) To furnish to the Managers a copy of each proposed free writing prospectus to be prepared by or on behalf of, used by, or referred to by the Company and not to use or refer to any proposed free writing prospectus to which the Managers reasonably object.

(d) Not to take any action that would result in an Underwriter or the Company being required to file with the Commission pursuant to Rule 433(d) under the Securities Act a free writing prospectus prepared by or on behalf of such Underwriter that such Underwriter otherwise would not have been required to file thereunder.

(e) If the Time of Sale Prospectus is being used to solicit offers to buy the Securities at a time when the Prospectus is not yet available to prospective purchasers and any event shall occur or condition exist as a result of which it is necessary to amend or supplement the Time of Sale Prospectus in order to make the statements therein, in the light of the circumstances, not misleading, or if any event shall occur or condition exist as a result of which the Time of Sale Prospectus conflicts with the information contained in the Registration Statement then on file, or if, in the opinion of counsel for the Underwriters, it is necessary to amend or supplement the Time of Sale Prospectus to comply with applicable law, forthwith to prepare, file with the Commission and furnish, at its own expense, to the Underwriters and to any dealer upon request, either amendments or supplements to the Time of Sale Prospectus so that the statements in the Time of

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Sale Prospectus as so amended or supplemented will not, in the light of the circumstances when the Time of Sale Prospectus is delivered to a prospective purchaser, be misleading or so that the Time of Sale Prospectus, as amended or supplemented, will no longer conflict with the Registration Statement, or so that the Time of Sale Prospectus, as amended or supplemented, will comply with applicable law.

(f) If, during such period after the first date of the public offering of the Securities as in the opinion of counsel for the Underwriters the Prospectus (or in lieu thereof the notice referred to in Rule 173(a) of the Securities Act) is required by law to be delivered in connection with sales by an Underwriter or dealer and prior to the completion of the distribution of the Securities, any event shall occur or condition exist as a result of which it is necessary to amend or supplement the Prospectus in order to make the statements therein, in the light of the circumstances when the Prospectus (or in lieu thereof the notice referred to in Rule 173(a) of the Securities Act) is delivered to a purchaser, not misleading, or if, in the opinion of counsel for the Underwriters, it is necessary to amend or supplement the Prospectus to comply with applicable law, forthwith to prepare, file with the Commission and furnish, at its own expense, to the Underwriters and to the dealers (whose names and addresses the Managers will furnish to the Company) to which Securities may have been sold by the Managers on behalf of the Underwriters and to any other dealers upon request, either amendments or supplements to the Prospectus so that the statements in the Prospectus as so amended or supplemented will not, in the light of the circumstances when the Prospectus (or in lieu thereof the notice referred to in Rule 173(a) of the Securities Act) is delivered to a purchaser, be misleading or so that the Prospectus, as amended or supplemented, will comply with applicable law.

(g) To endeavor to qualify the Securities for offer and sale under the securities or Blue Sky laws of such jurisdictions within the United States and Canada as the Representatives shall reasonably request; provided that in connection therewith the Company shall not be required to qualify as a foreign corporation or as a dealer in securities or to take any action that would subject it to general service of process in any such jurisdiction where it is not presently qualified or where it would be subject to taxation in respect of doing business in any jurisdiction which it otherwise would not.

(h) To make generally available to the Company’s security holders and to the Managers as soon as practicable an earning statement covering a period of at least twelve months beginning with the first fiscal quarter of the Company occurring after the date of this Agreement which shall satisfy the provisions of Section 11(a) of the Securities Act and the rules and regulations of the Commission thereunder, provided that the company may satisfy the requirements of this subsection (h) by electronically filing such reports or information through EDGAR.

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(i) Whether or not the transactions contemplated in this Agreement are consummated or this Agreement is terminated, to pay or cause to be paid all expenses incident to the performance of its obligations under this Agreement, including: (i) the fees, disbursements and expenses of the Company’s counsel and the Company’s accountants in connection with the registration and delivery of the Securities under the Securities Act and all other fees or expenses in connection with the preparation and filing of the Registration Statement, any preliminary prospectus, the Time of Sale Prospectus, the Prospectus, any free writing prospectus prepared by or on behalf of, used by, or referred to by the Company and amendments and supplements to any of the foregoing, including the filing fees payable to the Commission relating to the Securities (within the time required by Rule 456 (b)(1), if applicable), all printing costs associated therewith, and the mailing and delivering of copies thereof to the Underwriters and dealers, in the quantities hereinabove specified, (ii) all costs and expenses related to the transfer and delivery of the Securities to the Underwriters, including any transfer or other taxes payable thereon, (iii) the cost of printing or producing any Blue Sky or legal investment memorandum in connection with the offer and sale of the Securities under state securities laws and all expenses in connection with the qualification of the Securities for offer and sale under state securities laws as provided in Section 6(g) hereof, including filing fees and the reasonable fees and disbursements of counsel for the Underwriters in connection with such qualification and in connection with the Blue Sky or legal investment memorandum, (iv) all filing fees and the reasonable fees and disbursements of counsel to the Underwriters incurred in connection with the review and qualification of the offering of the Securities by the Financial Industry Regulatory Authority, (v) any fees charged by the rating agencies for the rating of the Securities, (vi) all costs and expenses incident to listing the Maximum Number of Underlying Securities on the NASDAQ, (vii) the cost of the preparation, issuance and delivery of the Securities, (viii) the costs and charges of any trustee, transfer agent, registrar or depositary, (ix) the costs and expenses of the Company relating to investor presentations on any “road show” undertaken in connection with the marketing of the offering of the Securities, including, without limitation, expenses associated with the preparation or dissemination of any electronic road show, expenses associated with the production of road show slides and graphics, fees and expenses of any consultants engaged in connection with the road show presentations with the prior approval of the Company, (x) the document production charges and expenses associated with printing this Agreement and (xi) all other costs and expenses incident to the performance of the obligations of the Company hereunder for which provision is not otherwise made in this Section. It is understood, however, that except as provided in this Section, Section 8 and the last paragraph of Section 10 below, the Underwriters will pay all of their costs and expenses, including fees and disbursements of their counsel, transfer taxes payable on resale of any of the Securities by them and any advertising expenses connected with any offers they may make.

(j) Reserved.

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(k) To prepare a final term sheet relating to the offering of the Securities, containing only information that describes the final terms of the Securities or the offering in a form consented to by the Managers, and to file such final term sheet within the period required by Rule 433(d)(5)(ii) under the Securities Act following the date the final terms have been established for the offering of the Securities.

(l) The Company will deliver to each Underwriter (or its agent), on the date of execution of this Agreement, a properly completed and executed Certification Regarding Beneficial Owners of Legal Entity Customers, together with copies of identifying documentation, and the Company undertakes to provide such additional supporting documentation as each Underwriter may reasonably request in connection with the verification of the foregoing Certification.

(m) To use its reasonable best efforts to have the Maximum Number of Underlying Securities approved for listing, subject only to notice of issuance, on the NASDAQ on or prior to the Closing Date and to maintain the listing of the Maximum Number of Underlying Securities on the NASDAQ.

(n) To reserve and keep available at all times, free of preemptive rights, the Maximum Number of Underlying Securities.

(o) Between the date hereof and the later of (i) the Closing Date and (ii) the Option Closing Date, if any, the Company will not do or authorize any act or thing that would, if it occurred after such Closing Date, result in an adjustment of the Conversion Rate (as such term is defined in the Indenture) for the Securities.

The Company also agrees that, without the prior written consent of the Manager identified in Schedule I with the authorization to release this lock-up on behalf of the Underwriters, it will not, during restricted period set forth in Schedule I hereto (the “Restricted Period”), (1) offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, lend, or otherwise transfer or dispose of, directly or indirectly, any shares of Common Stock or any securities convertible into or exercisable or exchangeable for Common Stock or (2) enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of the Common Stock, whether any such transaction described in clause (1) or (2) above is to be settled by delivery of Common Stock or such other securities, in cash or otherwise or (3) file any registration statement with the Commission relating to the offering of any shares of Common Stock or any securities convertible into or exercisable or exchangeable for Common Stock. The foregoing sentence shall not apply to (a) the sale of the Securities under this Agreement, (b) the issuance by the Company of the Underlying Securities upon the conversion of the Securities, (c) the issuance by the Company of any shares of Common Stock upon the exercise of an option or warrant or the conversion of a security outstanding on the date hereof and described in the Time of Sale Prospectus, (e) any shares of Common Stock issued by the Company pursuant to the Coriant Transaction as

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described in the Time of Sale Prospectus (e) any grants under the Company’s equity or stock plans in accordance with the terms of such plans as described in the Time of Sale Prospectus or (f) the entry into, or the consummation of the transactions contemplated by, the Capped Call Confirmations.

7. Covenants of the Underwriters. Each Underwriter severally covenants with the Company not to take any action that would result in the Company being required to file with the Commission under Rule 433(d) a free writing prospectus prepared by or on behalf of such Underwriter that otherwise would not be required to be filed by the Company thereunder, but for the action of the Underwriter.

8. Indemnity and Contribution. (a) The Company agrees to indemnify and hold harmless each Underwriter, each person, if any, who controls any Underwriter within the meaning of either Section 15 of the Securities Act or Section 20 of the Exchange Act and each affiliate of any Underwriter within the meaning of Rule 405 under the Securities Act from and against any and all losses, claims, damages and liabilities (including, without limitation, any legal or other expenses reasonably incurred in connection with defending or investigating any such action or claim) caused by any untrue statement or alleged untrue statement of a material fact contained in the Registration Statement or any amendment thereof, any preliminary prospectus, the Time of Sale Prospectus or any amendment or supplement thereto, any issuer free writing prospectus as defined in Rule 433(h) under the Securities Act, any Company information that the Company has filed, or is required to file, pursuant to Rule 433(d) under the Securities Act, any “road show” as defined in Rule 433(h) under the Securities Act (a “road show”), or the Prospectus or any amendment or supplement thereto, or caused by any omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading, except insofar as such losses, claims, damages or liabilities are caused by any such untrue statement or omission or alleged untrue statement or omission based upon information relating to any Underwriter furnished to the Company in writing by such Underwriter through the Managers expressly for use therein.

(b) Each Underwriter agrees, severally and not jointly, to indemnify and hold harmless the Company, its directors, its officers who sign the Registration Statement and each person, if any, who controls the Company within the meaning of either Section 15 of the Securities Act or Section 20 of the Exchange Act to the same extent as the foregoing indemnity from the Company to such Underwriter, but only with reference to information relating to such Underwriter furnished to the Company in writing by such Underwriter through the Managers expressly for use in the Registration Statement, any preliminary prospectus, the Time of Sale Prospectus, any issuer free writing prospectus, road show, or the Prospectus or any amendment or supplement thereto.

(c) In case any proceeding (including any governmental investigation) shall be instituted involving any person in respect of which indemnity may be sought pursuant to Section 8(a) or 8(b), such person (the “indemnified party”) shall promptly notify the person against whom such indemnity may be sought (the

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“indemnifying party”) in writing and the indemnifying party, upon request of the indemnified party, shall retain counsel reasonably satisfactory to the indemnified party to represent the indemnified party and any others the indemnifying party may designate in such proceeding and shall pay the fees and disbursements of such counsel related to such proceeding. In any such proceeding, any indemnified party shall have the right to retain its own counsel, but the fees and expenses of such counsel shall be at the expense of such indemnified party unless (i) the indemnifying party and the indemnified party shall have mutually agreed to the retention of such counsel or (ii) the named parties to any such proceeding (including any impleaded parties) include both the indemnifying party and the indemnified party and representation of both parties by the same counsel would be inappropriate due to actual or potential differing interests between them. It is understood that the indemnifying party shall not, in respect of the legal expenses of any indemnified party in connection with any proceeding or related proceedings in the same jurisdiction, be liable for the fees and expenses of more than one separate firm (in addition to any local counsel) for all such indemnified parties and that all such fees and expenses shall be reimbursed as they are incurred. Such firm shall be designated in writing by the Manager authorized to appoint counsel under this Section set forth in Schedule I hereto, in the case of parties indemnified pursuant to Section 8(a), and by the Company, in the case of parties indemnified pursuant to Section 8(b). The indemnifying party shall not be liable for any settlement of any proceeding effected without its written consent, but if settled with such consent or if there be a final judgment for the plaintiff, the indemnifying party agrees to indemnify the indemnified party from and against any loss or liability by reason of such settlement or judgment. Notwithstanding the foregoing sentence, if at any time an indemnified party shall have requested an indemnifying party to reimburse the indemnified party for fees and expenses of counsel as contemplated by the second and third sentences of this paragraph, the indemnifying party agrees that it shall be liable for any settlement of any proceeding effected without its written consent if (i) such settlement is entered into more than 60 days after receipt by such indemnifying party of the aforesaid request and (ii) such indemnifying party shall not have reimbursed the indemnified party in accordance with such request prior to the date of such settlement. No indemnifying party shall, without the prior written consent of the indemnified party, effect any settlement of any pending or threatened proceeding in respect of which any indemnified party is or could have been a party and indemnity could have been sought hereunder by such indemnified party, unless such settlement includes an unconditional release of such indemnified party from all liability on claims that are the subject matter of such proceeding.

(d) To the extent the indemnification provided for in Section 8(a) or 8(b) is unavailable to an indemnified party or insufficient in respect of any losses, claims, damages or liabilities referred to therein, then each indemnifying party under such paragraph, in lieu of indemnifying such indemnified party thereunder, shall contribute to the amount paid or payable by such indemnified party as a result of such losses, claims, damages or liabilities (i) in such proportion as is appropriate to reflect the relative benefits received by the Company on the one

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hand and the Underwriters on the other hand from the offering of the Securities or (ii) if the allocation provided by clause 8(d)(i) above is not permitted by applicable law, in such proportion as is appropriate to reflect not only the relative benefits referred to in clause 8(d)(i) above but also the relative fault of the Company on the one hand and of the Underwriters on the other hand in connection with the statements or omissions that resulted in such losses, claims, damages or liabilities, as well as any other relevant equitable considerations. The relative benefits received by the Company on the one hand and the Underwriters on the other hand in connection with the offering of the Securities shall be deemed to be in the same respective proportions as the net proceeds from the offering of the Securities (before deducting expenses) received by the Company and the total underwriting discounts and commissions received by the Underwriters bear to the aggregate initial public offering price of the Securities as set forth in the Prospectus. The relative fault of the Company on the one hand and the Underwriters on the other hand shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information supplied by the Company or by the Underwriters and the parties’ relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission. The Underwriters’ respective obligations to contribute pursuant to this Section 8 are several in proportion to the respective principal amounts of Securities they have purchased hereunder, and not joint.

(e) The Company and the Underwriters agree that it would not be just or equitable if contribution pursuant to this Section 8 were determined by pro rata allocation (even if the Underwriters were treated as one entity for such purpose) or by any other method of allocation that does not take account of the equitable considerations referred to in Section 8(d). The amount paid or payable by an indemnified party as a result of the losses, claims, damages and liabilities referred to in Section 8(d) shall be deemed to include, subject to the limitations set forth above, any legal or other expenses reasonably incurred by such indemnified party in connection with investigating or defending any such action or claim. Notwithstanding the provisions of this Section 8, no Underwriter shall be required to contribute any amount in excess of the amount by which the total price at which the Securities underwritten by it and distributed to the public were offered to the public exceeds the amount of any damages that such Underwriter has otherwise been required to pay by reason of such untrue or alleged untrue statement or omission or alleged omission. No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Securities Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation. The remedies provided for in this Section 8 are not exclusive and shall not limit any rights or remedies which may otherwise be available to any indemnified party at law or in equity.

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(f) The indemnity and contribution provisions contained in this Section 8 and the representations, warranties and other statements of the Company contained in this Agreement shall remain operative and in full force and effect regardless of (i) any termination of this Agreement, (ii) any investigation made by or on behalf of any Underwriter, any person controlling any Underwriter or any affiliate of any Underwriter or by or on behalf of the Company, its officers or directors or any person controlling the Company and (iii) acceptance of and payment for any of the Securities.

9. Termination. The Underwriters may terminate this Agreement by notice given by the Managers to the Company, if after the execution and delivery of this Agreement and prior to the Closing Date (i) trading generally shall have been suspended or materially limited on, or by, as the case may be, any of The New York Stock Exchange and the NASDAQ, (ii) trading of any securities of the Company shall have been suspended on any exchange or in any over-the-counter market, (iii) a material disruption in securities settlement, payment or clearance services in the United States shall have occurred, (iv) any moratorium on commercial banking activities shall have been declared by Federal or New York State authorities or (v) there shall have occurred any outbreak or escalation of hostilities, or any change in financial markets or any calamity or crisis that, in the Managers’ judgment, is material and adverse and which, singly or together with any other event specified in this clause (v), makes it, in the Managers’ judgment, impracticable or inadvisable to proceed with the offer, sale or delivery of the Securities on the terms and in the manner contemplated in the Time of Sale Prospectus or the Prospectus.

10. Effectiveness; Defaulting Underwriters. This Agreement shall become effective upon the execution and delivery hereof by the parties hereto.

If, on the Closing Date, or an Option Closing Date, as the case may be, any one or more of the Underwriters shall fail or refuse to purchase Securities that it has or they have agreed to purchase hereunder on such date, and the aggregate principal amount of Securities which such defaulting Underwriter or Underwriters agreed but failed or refused to purchase is not more than one-tenth of the aggregate principal amount of the Securities to be purchased on such date, the other Underwriters shall be obligated severally in the proportions that the principal amount of Firm Securities set forth opposite their respective names in Schedule II bears to the aggregate principal amount of Firm Securities set forth opposite the names of all such non-defaulting Underwriters, or in such other proportions as the Managers may specify, to purchase the Securities which such defaulting Underwriter or Underwriters agreed but failed or refused to purchase on such date; provided that in no event shall the principal amount of Securities that any Underwriter has agreed to purchase pursuant to this Agreement be increased pursuant to this Section 10 by an amount in excess of one-ninth of such principal amount of Securities without the written consent of such Underwriter. If, on the Closing Date, any Underwriter or Underwriters shall fail or refuse to purchase Firm Securities and the aggregate principal amount of Securities with respect to which such default occurs is more than one-tenth of the aggregate principal amount of Firm Securities to be purchased on such date, and arrangements satisfactory to the Managers and the Company for the purchase of such Firm Securities are not made within 36 hours after such default, this Agreement shall terminate without liability on the part of any non-defaulting Underwriter or the Company. In any such case either the Managers or the Company shall have the

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right to postpone the Closing Date, but in no event for longer than seven days, in order that the required changes, if any, in the Registration Statement, in the Time of Sale Prospectus, in the Prospectus or in any other documents or arrangements may be effected. If, on an Option Closing Date, any Underwriter or Underwriters shall fail or refuse to purchase Additional Securities and the aggregate principal amount of Additional Securities with respect to which such default occurs is more than one-tenth of the aggregate principal amount of Additional Securities to be purchased on such Option Closing Date, the non-defaulting Underwriters shall have the option to (a) terminate their obligation hereunder to purchase the Additional Securities to be sold on such Option Closing Date or (b) purchase not less than the principal amount of Additional Securities that such non-defaulting Underwriters would have been obligated to purchase in the absence of such default. Any action taken under this paragraph shall not relieve any defaulting Underwriter from liability in respect of any default of such Underwriter under this Agreement.

If this Agreement shall be terminated by the Underwriters, or any of them, because of any failure or refusal on the part of the Company to comply with the terms or to fulfill any of the conditions of this Agreement, or if for any reason the Company shall be unable to perform its obligations under this Agreement the Company will reimburse the Underwriters or such Underwriters as have so terminated this Agreement with respect to themselves, severally, for all out-of-pocket expenses (including the fees and disbursements of their counsel) reasonably incurred by such Underwriters in connection with this Agreement or the offering contemplated hereunder.

11. Entire Agreement. (a) This Agreement, together with any contemporaneous written agreements and any prior written agreements (to the extent not superseded by this Agreement) that relate to the offering of the Securities, represents the entire agreement between the Company and the Underwriters with respect to the preparation of any preliminary prospectus, the Time of Sale Prospectus, the Prospectus, the conduct of the offering, and the purchase and sale of the Securities.

(b) The Company acknowledges that in connection with the offering of the Securities: (i) the Underwriters have acted at arm’s length, are not agents of, and owe no fiduciary duties to, the Company or any other person, (ii) the Underwriters owe the Company only those duties and obligations set forth in this Agreement and prior written agreements (to the extent not superseded by this Agreement), if any, and (iii) the Underwriters may have interests that differ from those of the Company. The Company waives to the full extent permitted by applicable law any claims it may have against the Underwriters arising from an alleged breach of fiduciary duty in connection with the offering of the Securities.

12. Counterparts. This Agreement may be signed in two or more counterparts, each of which shall be an original, with the same effect as if the signatures thereto and hereto were upon the same instrument.

13. Applicable Law. This Agreement shall be governed by and construed in accordance with the internal laws of the State of New York.

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14. Headings. The headings of the sections of this Agreement have been inserted for convenience of reference only and shall not be deemed a part of this Agreement.

15. Notices. All communications hereunder shall be in writing and effective only upon receipt and if to the Underwriters shall be delivered, mailed or sent to the Managers at the address set forth in Schedule I hereto; and if to the Company shall be delivered, mailed or sent to the address set forth in Schedule I hereto.

16. Patriot Act Compliance. In accordance with the requirements of the USA Patriot Act, the Underwriters are required to obtain, verify and record information that identifies their respective clients, including the Company, which information may include the name and address of their respective clients, as well as other information that will allow the Underwriters to properly identify their respective clients.

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SCHEDULE I

I-1

I-2

SCHEDULE II

II-1

SCHEDULE III

Signatories to Lock-Up Agreements

Thomas J. Fallon

Brad D. Feller

David F. Welch, Ph.D.

David W. Heard

Robert J. Jandro

James L. Laufman

John P. Daane

Marcel Gani

Kambiz Y. Hooshmand

Paul J. Milbury

Rajal M. Patel

Mark A. Wegleitner

Oaktree Optical Holdings, L.P.

III-1

EXHIBIT A

FORM OF OPINION OF WILSON SONSINI GOODRICH & ROSATI,

PROFESSIONAL CORPORATION

1. The Company is a corporation duly incorporated and validly existing under the laws of the State of Delaware, and is in good standing under such laws. The Company has requisite corporate power and authority to own or lease, as the case may be, and to operate its properties and conduct its business as described in the Pricing Disclosure Package and Prospectus. The Company has been duly qualified as a foreign corporation for the transaction of business and is in good standing under the laws of the State of California.

2. The Company has the corporate power to authorize, issue and sell the Firm Securities as contemplated by the Underwriting Agreement.

3. The Underwriting Agreement has been duly authorized, executed and delivered by the Company.

4. The Indenture has been duly authorized by all necessary corporate action on the part of the Company and the Indenture has been duly executed and delivered by the Company and, assuming the due authorization, execution and delivery thereof by the Trustee, the Indenture constitutes a valid and binding instrument, enforceable against the Company in accordance with its terms; and the Indenture has been duly qualified under the Trust Indenture Act of 1939, as amended.

5. The Firm Securities have been duly authorized by all necessary corporate action of the Company and, when executed by the Company and authenticated by the Trustee in accordance with the terms of the Indenture (which authentication we have not determined by inspection of the Securities) and issued and delivered to the Underwriter against payment of the purchase price therefor specified in the Underwriting Agreement, the Firm Securities will constitute valid and binding obligations of the Company, enforceable against the Company in accordance with their terms; and the Firm Securities are entitled to the benefits of the Indenture.

6. The shares of Common Stock initially issuable upon conversion of the Firm Securities (assuming full physical settlement of the Firm Securities and including shares of Common Stock issuable with respect to any Make-Whole Fundamental Change (as defined in the Indenture) (the “Shares”) have been duly authorized and reserved for issuance upon conversion of the Firm Securities by all necessary corporate action on the part of the Company and the Shares, if any, when issued upon due conversion of the Firm Securities in accordance with the terms of the Firm Securities and the Indenture will be validly issued, fully paid and nonassessable and free of preemptive rights arising under the Certificate of Incorporation or Bylaws, the federal laws of the United States of America or the Delaware General Corporation Law and will conform in all material respects to the description thereof contained in the Pricing Disclosure Package and Prospectus under the caption “Description of Capital Stock.”

Exh. A-1

7. The execution and delivery by the Company of the Operative Documents, the performance by the Company of its obligations under the Operative Documents, and the issuance and sale of the Firm Securities and the issuance of the Shares or the consummation of any other of the transactions contemplated thereby do not violate or, with respect to clause (C) of this paragraph, constitute a default under, (A) any provision of the Certificate of Incorporation or Bylaws of the Company; (B) any provision of any federal or state law, rule or regulation known to us to be customarily applicable to transactions of the nature contemplated by the Underwriting Agreement; (C) any Reviewed Agreement; or (D) to our knowledge, any Reviewed Judgment.

8. No consent, approval, authorization of, or designation, declaration or filing with, any governmental authority on the part of the Company is required for the valid execution and delivery of the Operative Documents or the consummation of the transactions contemplated thereby, or the offer, sale or issuance of the Firm Securities or the issuance of the Shares, except such as have been obtained or made under the Securities Act and the Securities Exchange Act of 1934, as amended (the “Exchange Act”).

9. The information in the Pricing Disclosure Package and Prospectus under the caption “Description of Notes” insofar as such information purports to constitute a summary of the terms of the Securities and the Indenture, fairly and accurately summarizes the matters referred to therein in all material respects.

10. The information in the Pricing Disclosure Package and Prospectus under the caption “Description of Capital Stock”, insofar as such information purports to constitute a summary of the terms of the Common Stock, and under the caption “Underwriter”, insofar as such information purports to describe the provisions of the federal laws of the United States and the documents referred to therein, fairly and accurately summarizes the matters referred to therein in all material respects.

11. The information in the Pricing Disclosure Package and Prospectus under the caption “Material U.S. Federal Income Tax Considerations”, insofar as such information purports to constitute a summary of the United States federal tax laws and legal conclusions referred to therein, fairly and accurately summarizes the matters referred to therein in all material respects.

12. The Company is not and, immediately after giving effect to the offering and sale of the Securities to be sold by the Company and the application of the net proceeds thereof as described in the Pricing Disclosure Package and Prospectus, will not be required to register as an “investment company” as such term is defined in the Investment Company Act of 1940.

Exh. A-2

EXHIBIT B

[FORM OF LOCK-UP LETTER]

September __, 2018

Morgan Stanley & Co. LLC

As Manager of the several

Underwriters named

in Schedule II to the Underwriting Agreement

referred to below

c/o Morgan Stanley & Co. LLC

1585 Broadway

New York, New York 10036

Ladies and Gentlemen:

The undersigned understands that Morgan Stanley & Co. LLC (the “Manager”) proposes to enter into an Underwriting Agreement (the “Underwriting Agreement”) with Infinera Corporation, a Delaware corporation (the “Company”), providing for the public offering (the “Public Offering”) by the several Underwriters, including the Manager (the “Underwriters”), of its Convertible Senior Notes due 2024 (the “Securities”). The Securities will be convertible into cash, shares of common stock of the Company, par value $0.001 per share (the “Common Stock”), or a combination of cash and Common Stock, at the Company’s election.

To induce the Underwriters that may participate in the Public Offering to continue their efforts in connection with the Public Offering, the undersigned hereby agrees that, without the prior written consent of the Manager on behalf of the Underwriters, it will not, during the period commencing on the date hereof and ending 60 days after the date of the final prospectus (the “Restricted Period”) relating to the Public Offering (the “Final Prospectus”), (1) offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, lend, or otherwise transfer or dispose of, directly or indirectly, any shares of Common Stock beneficially owned (as such term is used in Rule 13d-3 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”)), by the undersigned or any other securities so owned convertible into or exercisable or exchangeable for Common Stock or (2) enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of the Common Stock, whether any such transaction described in clause (1) or (2) above is to be settled by delivery of Common Stock or such other securities, in cash or otherwise. The foregoing sentence shall not apply to (a) transfers of shares of Common Stock or any security convertible into Common Stock as a bona fide gift, (b) to the extent applicable, distributions of shares of Common Stock or any security convertible into Common Stock to limited partners or stockholders of the undersigned, (c) transfers of shares of Common

Exh. B-1

Stock or any security convertible into Common Stock to any trust, partnership or limited liability company for the direct or indirect benefit of the undersigned or the immediate family of the undersigned, (d) transfers of shares of Common Stock or any security convertible into Common Stock to a wholly owned subsidiary of the undersigned or to the direct or indirect members or partners of the undersigned, (e) transfers of shares of Common Stock or any security convertible into Common Stock by will or intestate, (f) transfers of shares of Common Stock or any security convertible into Common Stock to a nominee or custodian of a person or entity to whom a transfer would be permissible under clauses (a) through (e); provided that in the case of any transfer or distribution pursuant to clauses (a) through (f) (i) each donee or distributee shall sign and deliver a lock-up letter substantially in the form of this letter and (ii) no filing under Section 16(a) of the Exchange Act, reporting a reduction in beneficial ownership of shares of Common Stock, shall be required or shall be voluntarily made during the Restricted Period, (g) in connection with the surrender or forfeiture of shares to the Company solely to satisfy tax withholding obligations upon exercise or vesting of stock options or awards; provided that no filing under Section 16(a) of the Exchange Act shall be voluntarily made and any filing under Section 16(a) of the Exchange Act required to made during the Restricted Period in connection with any such transfers or dispositions shall indicate by footnote disclosure or otherwise the nature of the transfer or disposition, (h) the establishment of a trading plan pursuant to Rule 10b5-1 under the Exchange Act for the transfer of shares of Common Stock, provided that (A) such plan does not provide for the transfer of Common Stock during the Restricted Period and (B) to the extent a public announcement or filing under the Exchange Act, if any, is required of or voluntarily made by or on behalf of the undersigned or the Company regarding the establishment of such plan, such announcement or filing shall include a statement to the effect that no transfer of Common Stock may be made under such plan during the Restricted Period or (i) sales of shares of Common Stock pursuant to a trading plan established pursuant to Rule 10b5-1 under the Exchange Act, provided that such trading plan was established prior to the date hereof and made available to the Manager or its counsel. In addition, the undersigned agrees that, without the prior written consent of the Manager on behalf of the Underwriters, it will not, during the Restricted Period, make any demand for or exercise any right with respect to, the registration of any shares of Common Stock or any security convertible into or exercisable or exchangeable for Common Stock. The undersigned also agrees and consents to the entry of stop transfer instructions with the Company’s transfer agent and registrar against the transfer of the undersigned’s shares of Common Stock except in compliance with the foregoing restrictions.

It is understood that the undersigned will be released from its obligations under this “lock-up” agreement if the Company notifies the undersigned that it does not intend to proceed with the Public Offering, if the Underwriting Agreement (other than the provisions thereof that survive termination) shall terminate or be terminated prior to payment for and delivery of the Securities or if the Offering shall not have occurred by October 31, 2018.

The undersigned understands that the Company and the Underwriters are relying upon this agreement in proceeding toward consummation of the Public Offering. The undersigned further understands that this agreement is irrevocable and shall be binding upon the undersigned’s heirs, legal representatives, successors and assigns.

Exh. B-2

Whether or not the Public Offering actually occurs depends on a number of factors, including market conditions. Any Public Offering will only be made pursuant to the Underwriting Agreement, the terms of which are subject to negotiation between the Company and the Underwriters.

Exh. B-3

EXHIBIT C

FORM OF CFO CERTIFICATE

INFINERA CORPORATION

CERTIFICATE OF THE CHIEF FINANCIAL OFFICER

September [•], 2018

Reference is hereby made to the Underwriting Agreement, dated September [•], 2018 (the “Underwriting Agreement”), among Infinera Corporation (the “Company”) and Morgan Stanley & Co. LLC as manager of the several underwriters named on Schedule II thereto (the “Underwriters”). Capitalized terms used but not defined in this certificate have the meaning assigned to them in the Underwriting Agreement.

I am responsible for the financial accounting matters of the Company and am familiar with the accounting books and records and internal controls of the Company. To assist the Underwriters in conducting and documenting their investigation of the affairs of the Company, I, Brad Feller, in my capacity as Chief Financial Officer of the Company, do hereby certify pursuant to Section 5(h) of the Underwriting Agreement that after reasonable inquiry and investigation by myself or members of my staff who are responsible for the Company’s financial and accounting matters:

The items marked with an “A” on the pages of the Prospectus attached as Exhibit A hereto (a) are prepared on a basis substantially consistent with the latest audited financial statements of the Company included or incorporated by reference in the Prospectus, (b) are derived from the accounting books and records of the Company, (c) fairly present, in all material respects, an accurate range of the financial performance or position of the Company as of and for the fiscal quarter ended June 30, 2018, and (d) are prepared in conformity with generally accepted accounting principles where applicable. In addition, nothing has come to my attention that would cause me to believe that the actual financial results of the Company as of and for the fiscal quarter ended June 30, 2018, once finalized, will differ in any material respect from such information.

Exh. C-1