As filed with the Securities and Exchange Commission on May 31, 2018

Registration No. 333-224991

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Amendment No. 1

to

FORM S-4

REGISTRATION STATEMENT

Under

the Securities Act of 1933

LUMENTUM HOLDINGS INC.

(Exact name of Registrant as specified in its charter)

400 North McCarthy Boulevard

Milpitas, CA 95035

(408) 546-5483

(Address, including zip code, and telephone number, including area code, of Registrant’s principal executive offices)

Alan Lowe

President and Chief Executive Officer

Lumentum Holdings Inc.

400 N. McCarthy Boulevard

Milpitas, CA 95035

(408) 546-5000

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Approximate date of commencement of proposed sale of the securities to the public: As soon as practicable after this registration statement becomes effective and upon completion of the Merger described in the enclosed document.

If the securities being registered on this Form are being offered in connection with the formation of a holding company and there is compliance with General Instruction G, check the following box.  ☐

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act:

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.  ☐

If applicable, place an X in the box to designate the appropriate rule provision relied upon in conducting this transaction:

Exchange Act Rule 13e-4(i) (Cross-Border Issuer Tender Offer)  ☐

Exchange Act Rule 14d-l(d) (Cross-Border Third-Party Tender Offer)  ☐

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until the Registration Statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

The information in this proxy statement/prospectus is not complete and may be changed. We may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This proxy statement/prospectus is not an offer to sell these securities and we are not soliciting an offer to buy  these  securities  in  any  jurisdiction  where  the  offer  or  sale  is  not  permitted.

PRELIMINARY PROXY STATEMENT/PROSPECTUS—SUBJECT TO COMPLETION,

DATED May 31, 2018

MERGER PROPOSAL—YOUR VOTE IS VERY IMPORTANT

Dear Oclaro Stockholders:

On March 11, 2018, Lumentum Holdings Inc. (“Lumentum”), Prota Merger Sub, Inc. (“Merger Sub”), and Prota Merger, LLC (“Merger Sub LLC”), and Oclaro, Inc. (“Oclaro”) entered into an Agreement and Plan of Merger (the “Merger Agreement”), pursuant to which Lumentum will acquire Oclaro in a merger transaction.

Upon the terms and subject to the conditions of the Merger Agreement, Merger Sub will merge with and into Oclaro (the “First Step Merger”, and the time at which the First Step Merger is effective, the “Effective Time”). As soon as practicable following the First Step Merger, and as the second step in a single integrated transaction with the First Step Merger, Lumentum will cause Oclaro to merge with and into Merger Sub LLC (the “Second Step Merger” and, taken together with the First Step Merger, the “Merger”), with Merger Sub LLC surviving as a direct wholly owned subsidiary of Lumentum. If the Merger is completed, Oclaro stockholders will receive, in exchange for each outstanding share of Oclaro common stock owned immediately prior to the Merger (1) $5.60 in cash without interest (the “Cash Consideration”) and (2) 0.0636 of a share of Lumentum common stock, subject to the conditions and restrictions set forth in the Merger Agreement (the “Stock Consideration” and, together with the Cash Consideration, the “Merger Consideration”). The proportion of Cash Consideration and Stock Consideration is subject to adjustment in certain limited circumstances, as described in the accompanying proxy statement/prospectus.

Based on the closing stock price of Lumentum common stock on March 9, 2018, the last trading day before the day on which Lumentum and Oclaro announced the execution of the Merger Agreement, the per share value of Oclaro common stock implied by the Merger Consideration was $9.99. Based on the closing stock price of Lumentum common stock on May 29, 2018, the most recent practicable date prior to the date of the accompanying proxy statement/prospectus, the per share value of Oclaro common stock implied by the Merger Consideration was $9.60. The implied value of the Merger Consideration will fluctuate as the market price of Lumentum common stock fluctuates because a portion of the Merger Consideration is payable in a fixed number of shares of Lumentum common stock. As a result, the value of the Merger Consideration that Oclaro stockholders will receive upon completion of the Merger could be greater than, less than or the same as the implied value of the Merger Consideration on May 29, 2018, or at the time of the Oclaro special meeting described in the accompanying proxy statement/prospectus (referred to as the special meeting).

It is expected that, immediately after completion of the Merger, former Oclaro stockholders will own approximately 16% of the outstanding shares of Lumentum common stock.

The Merger is intended to qualify as a reorganization for U.S. federal income tax purposes, but its qualification as such depends upon the value of the Stock Consideration relative to the value of the total Merger Consideration, which cannot be finally determined until after the closing of the Merger. It is possible that the Merger will not qualify as a reorganization for U.S. federal income tax purposes, in which case it would be a fully taxable transaction. On the date of the closing of the Merger, Lumentum and Oclaro will make a determination, in consultation with their tax counsel, as to whether or not the Merger qualifies as a reorganization for U.S. federal income tax purposes, and Lumentum will inform the Oclaro stockholders of such determination as soon as practicable after the Closing. We encourage Oclaro stockholders to carefully review the information under the heading “Material U.S. Federal Income Tax Consequences” of this proxy statement/prospectus for a description of certain U.S. tax consequences of the Merger.

Oclaro will hold a special meeting of its stockholders to vote on matters related to the proposed Merger. The special meeting will be held on July 10, 2018, at 8:00 a.m., Pacific time, at Oclaro’s headquarters located at 225 Charcot Avenue, San Jose, California 95131. At the special meeting, Oclaro stockholders will be asked to adopt the Merger Agreement (the “Merger Proposal”). In addition, Oclaro stockholders will be asked to approve, on a non-binding, advisory basis, the compensation payments that will or may be made to Oclaro’s named executive officers in connection with the Merger (the “Compensation Proposal”) and to approve the adjournment of the special meeting, if necessary or appropriate, to solicit additional proxies if there are not sufficient votes at the time of the special meeting to adopt the Merger Agreement (the “Adjournment Proposal”).

The Oclaro board of directors unanimously recommends that Oclaro stockholders vote “FOR” the Merger Proposal, “FOR” the Compensation Proposal and “FOR” the Adjournment Proposal.

Your vote is very important. We cannot complete the Merger without the adoption of the Merger Agreement by Oclaro stockholders. It is important that your shares be represented and voted regardless of the size of your holdings. A failure to vote will have the same effect as a vote “AGAINST” the adoption of the Merger Agreement. Whether or not you plan to attend the special meeting, we urge you to submit a proxy to have your shares voted in advance of the special meeting by using one of the methods described in the accompanying proxy statement/prospectus.

The accompanying proxy statement/prospectus provides important information regarding the special meeting and a detailed description of the Merger Agreement, the Merger and the matters to be presented at the special meeting. We urge you to read the accompanying proxy statement/prospectus carefully and in its entirety. Please pay particular attention to the section titled “Risk Factors” beginning on page 57 of the accompanying proxy statement/prospectus.

We look forward to seeing you at the special meeting and, on behalf of the Oclaro board of directors, thank you for your continued support.

Sincerely,

Marissa Peterson

Chairman of the Board of Directors

May 31, 2018

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of the Merger or the securities to be issued in connection with the Merger or determined if this proxy statement/prospectus is accurate or complete. Any representation to the contrary is a criminal offense.

The accompanying proxy statement/prospectus is dated May 31, 2018 and is first being mailed to Oclaro stockholders on or about June 4, 2018.

OCLARO, INC.

225 Charcot Avenue

San Jose, California 95131

NOTICE OF SPECIAL MEETING OF STOCKHOLDERS

To Be Held on July 10, 2018

To the Stockholders of Oclaro, Inc.:

The special meeting of stockholders of Oclaro, Inc., a Delaware corporation (“Oclaro”), will be held on July 10, 2018 at 8:00 a.m., Pacific time, at Oclaro’s headquarters located at 225 Charcot Avenue, San Jose, California 95131, for the purpose of considering and voting upon the following matters:

The accompanying proxy statement/prospectus describes the proposals listed above in more detail. Please refer to the accompanying proxy statement/prospectus, including the Merger Agreement and the other annexes and documents included in, or incorporated by reference into, the accompanying proxy statement/prospectus, for further information with respect to the business to be transacted at the special meeting. You are encouraged to read the entire proxy statement/prospectus carefully before voting. In particular, see the section titled “Risk Factors” beginning on page 57 of this proxy statement/prospectus.

The Oclaro board of directors unanimously determined that the Merger, the Merger Agreement and the other transactions contemplated by the Merger Agreement are advisable, fair to and in the best interests of Oclaro and its stockholders and approved and declared advisable the Merger Agreement, the Merger and the other transactions contemplated by the Merger Agreement. The Oclaro board of directors unanimously recommends that Oclaro stockholders vote “FOR” the Merger Proposal, “FOR” the Compensation Proposal and “FOR” the Adjournment Proposal.

The Oclaro board of directors has fixed the close of business on May 15, 2018 as the record date for determination of Oclaro stockholders entitled to receive notice of, and to vote at, the special meeting or any adjournments or postponements thereof. Only holders of record of Oclaro common stock as of the close of business on the record date are entitled to receive notice of, and to vote at, the special meeting.

YOUR VOTE IS VERY IMPORTANT, REGARDLESS OF THE NUMBER OF SHARES THAT YOU OWN. The Merger cannot be completed unless the Merger Proposal is adopted by the affirmative vote, in person or by proxy, of holders of a majority of the outstanding shares of Oclaro common stock as of the record date. The affirmative vote, in person or by proxy, of holders of a majority of the voting power of the shares of Oclaro common stock present in person or represented by proxy at the special meeting and voting on the matter is required to approve the Compensation Proposal and the Adjournment Proposal.

Whether or not you expect to attend the special meeting in person, Oclaro urges you to submit a proxy to have your shares voted as promptly as possible by either: (1) submitting your proxy by properly signing, dating and returning the enclosed proxy card in the accompanying prepaid reply envelope, which you should do early enough so that it is received before the date of the special meeting; (2) submitting your proxy by using the Internet at www.proxyvote.com; or (3) submitting your proxy by calling 1-800-690-6903, the toll-free (within the U.S. or Canada) phone number on your proxy card. If your shares are held in the name of a bank, brokerage firm or other nominee, please follow the instructions on the voting instruction card furnished by such bank, brokerage firm or other nominee. Any stockholder of record attending the special meeting may vote in person even if such stockholder has returned a proxy card.

If you have any questions about the special meeting, the Merger, the proposals or the accompanying proxy statement/prospectus, would like additional copies of the proxy statement/prospectus, need to obtain proxy cards or other information related to this proxy solicitation or need help submitting a proxy or voting your shares of Oclaro common stock, please contact Oclaro’s proxy solicitor:

MacKenzie Partners, Inc.

1407 Broadway

New York, New York 10018

(212) 929-5500

or

Toll-Free (800) 322-2885

Oclaro will transact no other business at the special meeting, except for business properly brought before the special meeting or any adjournment or postponement thereof. Our board of directors has no knowledge of any other business to be transacted at the special meeting.

San Jose, California

May 31, 2018

ADDITIONAL INFORMATION

This proxy statement/prospectus incorporates by reference important business and financial information about Lumentum and Oclaro from other documents that Lumentum and Oclaro have filed with the United States Securities and Exchange Commission (“SEC”) and that are not included in or delivered with this proxy statement/prospectus. This information is available for you to review at the SEC’s public reference room located at 100 F Street, N.E., Room 1580, Washington, D.C. and through the SEC’s website at www.sec.gov. You can obtain copies of this proxy statement/prospectus and the documents incorporated by reference into this proxy statement/prospectus free of charge by requesting them in writing or by telephone from the appropriate company at the following addresses and telephone numbers:

Investors may also consult Lumentum’s and Oclaro’s websites for more information concerning the Merger described in this proxy statement/prospectus. Lumentum’s website is www.lumentum.com and Oclaro’s website is www.oclaro.com. Information included on these websites is not incorporated by reference into this proxy statement/prospectus.

In addition, if you have questions about the Merger, the special meeting, or the proposals to be considered at the special meeting, need additional copies of this document and the annexes to this document, or need to obtain proxy cards or other information related to the proxy solicitation, you may contact Oclaro’s proxy solicitor, MacKenzie Partners, Inc., at the address and telephone number set forth above. You will not be charged for any of these documents that you request.

If you would like to request any documents, please do so by July 2, 2018 in order to receive them before the special meeting.

For more information, please see the section titled “Where You Can Find More Information” beginning on page 169 of this proxy statement/prospectus.

ABOUT THIS PROXY STATEMENT/PROSPECTUS

This proxy statement/prospectus, which forms part of a registration statement on Form S-4 filed with the SEC by Lumentum, constitutes a prospectus of Lumentum under Section 5 of the Securities Act of 1933, as amended (the “Securities Act”), with respect to the shares of Lumentum common stock to be issued pursuant to the Merger. This proxy statement/prospectus also constitutes a proxy statement for Oclaro under Section 14(a) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”). It also constitutes a notice of meeting with respect to the special meeting.

You should rely only on the information contained in or incorporated by reference into this proxy statement/prospectus. No one has been authorized to provide you with information that is different from that contained in, or incorporated by reference into, this proxy statement/prospectus. Lumentum and Oclaro take no responsibility for, and can provide no assurances as to the reliability of, any other information that others may give you and, if given, such information must not be relied on as having been authorized. This proxy statement/prospectus is dated May 31, 2018. You should not assume that the information contained in this proxy statement/prospectus is accurate as of any date other than that date. You should not assume that the information incorporated by reference into this proxy statement/prospectus is accurate as of any date other than the date of the incorporated document. Neither the mailing of this proxy statement/prospectus to Oclaro stockholders nor the issuance by Lumentum of shares of Lumentum common stock in connection with the Merger will create any implication to the contrary.

This proxy statement/prospectus does not constitute an offer to sell, or a solicitation of an offer to buy, any securities, or the solicitation of a proxy, in any jurisdiction to or from any person to whom it is unlawful to make any such offer or solicitation. Information contained in this proxy statement/prospectus regarding Lumentum has been provided by Lumentum and information contained in this proxy statement/prospectus regarding Oclaro has been provided by Oclaro.

All references in this proxy statement/prospectus to “Lumentum” refer to Lumentum Holdings Inc., a Delaware corporation, and its consolidated subsidiaries, unless the context requires otherwise; all references in this proxy statement/prospectus to “Oclaro” refer to Oclaro, Inc., a Delaware corporation, and its consolidated subsidiaries, unless the context requires otherwise; all references to “Merger Sub” refer to Prota Merger Sub, Inc., a Delaware corporation and a wholly owned subsidiary of Lumentum formed for the sole purpose of effecting the Merger; and all references to “Merger Sub LLC” refer to Prota Merger, LLC, a Delaware limited liability company and a wholly owned subsidiary of Lumentum; unless otherwise indicated or as the context requires, all references in this proxy statement/prospectus to “we,” “our” and “us” refer to Lumentum and Oclaro, collectively; unless otherwise indicated or as the context requires, all references to the “Merger Agreement” refer to the Agreement and Plan of Merger dated as of March 11, 2018, as it may be amended from time to time in accordance with its terms, by and among Lumentum, Merger Sub, Merger Sub LLC and Oclaro, a copy of which is included as Annex A to this proxy statement/prospectus. All summaries of, and references to, the Merger Agreement described in this proxy statement/prospectus are qualified by the full copy of and complete text of the Merger Agreement in the form attached hereto as an Annex A. Also, in this proxy statement/prospectus, “$” refers to U.S. dollars.

Oclaro stockholders should not construe the contents of this proxy statement/prospectus as legal, tax or financial advice. Oclaro stockholders should consult with their own legal, tax, financial or other professional advisors.

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TABLE OF CONTENTS

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QUESTIONS AND ANSWERS

The following are some questions that you, as a stockholder of Oclaro, Inc. (“Oclaro”) may have regarding the Merger (as defined below) and the other matters being considered at the special meeting and the answers to those questions. Lumentum Holdings Inc. (“Lumentum”) and Oclaro urge you to carefully read the remainder of this proxy statement/prospectus because the information in this section does not provide all the information that might be important to you with respect to the Merger and the other matters being considered at the special meeting. Additional important information is also contained in the Annexes to, and the documents incorporated by reference into, this proxy statement/prospectus.

Questions and Answers about the Merger

The Merger cannot be completed unless, among other things, holders of a majority of shares of outstanding Oclaro common stock as of the Record Date (as defined below) for the special meeting of Oclaro stockholders (the “special meeting”) vote to adopt the Merger Agreement. The Oclaro board of directors (the “Oclaro Board”) unanimously recommends that stockholders vote “FOR” the adoption of the Merger Agreement. Your failing to submit a proxy or vote in person at the special meeting, your abstaining from voting, or your failing to provide your bank, brokerage firm or other nominee with instructions on how to vote your shares, as applicable, will have the same effect as a vote “AGAINST” the adoption of the Merger Agreement.

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Accordingly, the value of the Merger Consideration that Oclaro stockholders will receive upon completion of the Merger could be greater than, less than or the same as the implied value of the Merger Consideration on March 9, 2018, on May 29, 2018, the most recent practicable date prior to the date of the accompanying proxy statement/prospectus, or at the time of the special meeting. Accordingly, you should obtain current stock price quotations for Lumentum common stock and Oclaro common stock before deciding whether to vote in favor of the Merger. Lumentum common stock and Oclaro common stock trade on the NASDAQ Global Select Market (“NASDAQ”) under the symbols “LITE” and “OCLR,” respectively.

Factors that could give rise to the Stock Threshold being exceeded include, among others, (i) there being more shares of Oclaro common stock outstanding at the Effective Time than on March 9, 2018, the last trading day before the day on which Lumentum and Oclaro announced the execution of the Merger Agreement, (ii) there being less shares of Lumentum common stock outstanding at the Effective Time than on March 9, 2018, or (iii) the Parent Average Closing Price (which is used to calculate the exchange ratio for conversion of Oclaro’s outstanding equity awards, as described and defined below) being lower than $68.975, the closing price of Lumentum common stock on March 9, 2018. For example, (a) if the Parent Average Closing Price at the Effective Time is $60.00, (b) Oclaro issues all equity awards it is entitled to issue under the Merger Agreement and (c) there are not more shares of Lumentum common stock outstanding at the Effective Time than were outstanding on March 9, 2018, the Stock Threshold would be

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exceeded because more than 19.9% of the outstanding shares of Lumentum common stock would need to be issued in connection with the Merger Consideration and the assumption and conversion of Oclaro’s outstanding equity awards. As such, the Exchange Ratio would be decreased from 0.0636 to 0.0620 and $0.11 of Supplemental Cash Consideration would be payable per share of Oclaro common stock, which would be added to the Cash Consideration for a total amount of cash of $5.71 payable per share of Oclaro common stock.

In addition, any Oclaro RSU that is vested and unsettled will be treated as outstanding Oclaro common stock and will receive the Merger Consideration, subject to applicable tax withholding.

Each share of Oclaro common stock subject to vesting or lapse restrictions (“Oclaro Restricted Stock”) that is outstanding and unvested immediately before the Effective Time shall become fully vested at the Effective Time and will be treated as outstanding Oclaro common stock and will receive the Merger Consideration, subject to applicable tax withholding.

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Except as provided in the next paragraph, each option (or portion thereof) to purchase shares of Oclaro common stock (each, an “Oclaro Option”) that is outstanding, whether vested or unvested, immediately before the Effective Time will be assumed by Lumentum (each, an “Assumed Option”) on substantially the same terms and conditions as applied to the related Oclaro Option immediately before the Effective Time (including the applicable vesting schedule), except (A) the number of shares of Lumentum common stock subject to each Assumed Option will equal the product of (x) the number of shares of Oclaro common stock underlying such Assumed Option immediately before the Effective Time multiplied by (y) the Equity Award Exchange Ratio (rounded down to the nearest whole share), and (B) the per share exercise price of each Assumed Option will equal the quotient determined by dividing (x) the exercise price per share of such Assumed Option immediately before the Effective Time by (y) the Equity Award Exchange Ratio (rounded up to the nearest whole cent).

Each Oclaro Option (or portion thereof) that is outstanding and vested immediately before the Effective Time (or vests as a result of the Merger) and held by a holder who is not an employee of Oclaro or its subsidiaries immediately before the Effective Time (each, a “Cancelled Oclaro Option”) will be cancelled and converted into the right to receive the Merger Consideration in respect of each “net option share” of Oclaro common stock covered by such Cancelled Oclaro Option, subject to applicable tax withholding. The number of “net option shares” will be determined under a formula specified in the Merger Agreement that takes into account the exercise price of such Cancelled Oclaro Option. Any fractional net option shares (after aggregating all shares represented by all Cancelled Oclaro Options held by such holder) will be settled in cash based on the cash equivalent value of the Merger Consideration, subject to applicable tax withholding. If the exercise price per share of any Cancelled Oclaro Option is equal to or greater than the Merger Consideration, such Cancelled Oclaro Option will be cancelled without payment of any consideration.

Each stock appreciation right (or portion thereof) related to Oclaro common stock (each, an “Oclaro SAR”) that is outstanding, whether vested or unvested, will be cancelled and converted into the right to receive a cash amount equal to the product of (x) the number of shares of Oclaro common stock issuable upon exercise of the Oclaro SAR, multiplied by (y) the excess, if any of (1) the cash equivalent value of the Merger Consideration over (2) the strike price of such Oclaro SAR, subject to applicable tax withholding.

Any applicable taxes required to be withheld from the Merger Consideration payable in respect of vested Oclaro RSUs, Oclaro Restricted Stock, and/or Cancelled Oclaro Options will first reduce the Cash Consideration portion of the Merger Consideration, with any remaining amount reducing the Stock Consideration portion of the Merger Consideration (with the value of the stock portion for purposes of such deduction determined based on Lumentum’s average closing sale price (rounded to the nearest one tenth of a cent), as reported on NASDAQ for the ten most recent trading days ending on the third trading day before the Effective Time (the “Parent Average Closing Price”)).

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If the Merger qualifies as a reorganization, a U.S. Holder (as defined below in this proxy statement/prospectus) of Oclaro common stock receiving Lumentum common stock and cash in exchange for Oclaro common stock will generally recognize gain equal to the lesser of (i) the amount of cash received by the U.S. Holder (excluding any cash received in lieu of fractional shares of Lumentum common stock) and (ii) the excess of the “amount realized” by the U.S. Holder over the U.S. Holder’s tax basis in the Oclaro common stock. The “amount realized” by the U.S. Holder will equal the sum of the fair market value of the Lumentum common stock and the amount of cash (including any cash received in lieu of fractional shares of Lumentum common stock) received by the U.S. Holder. Losses will not be permitted to be recognized. Realized gain or loss must be calculated separately for each identifiable block of shares (i.e. shares acquired at different times and prices) exchanged in the Merger, and a loss realized on the exchange of one block cannot be used to offset a gain recognized on the exchange of another block.

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If the Merger does not qualify as a reorganization, the exchange of Oclaro common stock for Lumentum common stock and cash in the First Step Merger will be a fully taxable transaction, in which a U.S. Holder generally will recognize gain or loss equal to the difference between the “amount realized” (as defined above) and the U.S. Holder’s tax basis in the Oclaro common stock. Gain or loss must be calculated separately for each identifiable block of shares exchanged in the First Step Merger. Long-term capital gains of non-corporate taxpayers are generally eligible for preferential rates of taxation. Deductions for capital losses are subject to limitations. Any gain recognized by a non-corporate U.S. holder may be subject to a 3.8% Medicare tax on net investment income.

You should consult your own tax advisor to determine the U.S. federal income tax consequences to you relating to the Merger in light of your own particular circumstances and the consequences to you arising under U.S. federal non-income tax laws or the laws of any state, local or non-U.S. taxing jurisdiction. A more complete description of material U.S. federal income tax consequences of the Merger is provided in the section titled “Material U.S. Federal Income Tax Consequences” beginning on page 152 of this proxy statement/prospectus.

Questions and Answers about the Special Meeting

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Approval by Oclaro stockholders of the Merger Proposal (the “Oclaro Stockholder Approval”) is required for completion of the Merger. Approval by Oclaro stockholders of the Compensation Proposal and the Adjournment Proposal is not required for completion of the Merger. No other matters are intended to be brought before the special meeting by Oclaro. However, if other matters are properly brought before the special meeting or at any adjournment or postponement of the special meeting, the persons whom the Oclaro Board has appointed to vote proxies will vote on such matters in their discretion.

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A control number, located on your proxy card, is designed to verify your identity and allow you to vote your shares of Oclaro common stock and to confirm that your voting instructions have been properly recorded when voting electronically over the Internet or by telephone. Although there is no charge for voting your shares of Oclaro common stock, if you vote electronically over the Internet or by telephone, you may incur costs such as Internet access and telephone charges for which you will be responsible.

Even if you plan to attend the special meeting in person, you are strongly encouraged to vote your shares of Oclaro common stock by proxy. If you are a record holder or if you obtain a proxy to vote shares of Oclaro common stock that you beneficially own, you may still vote your shares of Oclaro common stock in person by ballot at the special meeting even if you have previously voted by proxy. If you are present at the special meeting and vote in person by ballot, your previous vote by proxy will not be counted.

If your shares of Oclaro common stock are held in “street name” through a broker, bank or other nominee, you may vote through your broker, bank or other nominee by completing and returning the voting instruction form provided by your broker, bank or other nominee, or, if such a service is provided by your broker, bank or other nominee, electronically over the Internet or by telephone. To vote over the Internet or by telephone through your broker, bank or other nominee, you should follow the instructions on the voting instruction form provided by your broker, bank or nominee. However, because you are not the stockholder of record, you may not vote your shares of Oclaro common stock in person by ballot at the special meeting unless you obtain a proxy from your broker, bank or other nominee giving you the right to vote your shares at the special meeting. Please refer to the voting instruction card provided with these proxy materials by your broker, bank or other nominee or contact your broker, bank or other nominee to obtain instructions on how to instruct them with respect to the voting of your shares of Oclaro common stock.

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Your broker, bank or other nominee is permitted to vote your shares of Oclaro common stock on any proposal currently scheduled to be considered at the special meeting only if you instruct your broker, bank or other nominee how to vote. You should follow the procedures provided by your broker, bank or other nominee to vote your shares of Oclaro common stock. Without instructions, your shares will not be voted on such proposals, which will have the same effect as if you voted “AGAINST” the Merger Proposal, but will have no effect on the Compensation Proposal or the Adjournment Proposal. The Oclaro Board strongly encourages you to provide voting instructions to your bank, brokerage firm or other nominee so that your vote will be counted on all matters.

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If you are a beneficial owner of shares held in “street name” by a broker, bank or other nominee, you may revoke your proxy and vote your shares in person at the special meeting only in accordance with the applicable rules and procedures employed by such broker, bank or other nominee. If your shares are held in an account at a broker, bank or other nominee, you should contact your broker, bank or other nominee to change your vote.

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MacKenzie Partners, Inc.

1407 Broadway

New York, New York 10018

(212) 929-5500

or

Toll-Free (800) 322-2885

You may also contact the Oclaro Investor Relations department at:

Oclaro, Inc.

225 Charcot Avenue

San Jose, California 95131

Telephone: (408) 383-1400

Attn: Investor Relations

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THE COMPANIES

Lumentum Holdings Inc.

Lumentum is an industry leading provider of optical and photonic products addressing a range of end market applications including data communications and telecommunications networking and commercial lasers for manufacturing, inspection and life-science applications, as defined by revenue and market share. In addition, Lumentum is using its core optical and photonic technology and its volume manufacturing capability to expand into emerging markets that benefit from advantages that optical or photonics-based solutions provide, including 3D sensing for consumer electronics and diode light sources for a variety of consumer and industrial applications. The majority of Lumentum’s customers are original equipment manufacturers that incorporate Lumentum’s products into their products which address end-market applications. For example, Lumentum sells fiber optic components that its network equipment manufacturer customers assemble into communications networking systems, which they sell to network service providers or enterprises with their own networks. Increasingly, Lumentum is also selling data communications products to owners and operators of large data centers, which Lumentum refers to as hyperscale datacenters. Similarly, many of Lumentum’s customers for its Lasers products incorporate Lumentum’s products into tools they produce, which are used for manufacturing processes by their customers. Lumentum operates in two reportable segments: optical communications and commercial lasers. Lumentum has a global marketing and sales footprint that enables it to address global market opportunities for its products. Lumentum has manufacturing capabilities and facilities in North America, Asia-Pacific and Europe, the Middle East and Africa with employees engaged in R&D, administration, manufacturing, support and sales and marketing activities.

Lumentum was incorporated in Delaware as a wholly owned subsidiary of JDS Uniphase Corporation (“JDSU”) on February 10, 2015 and is comprised of the former communications and commercial optical products segment and WaveReady product lines of JDSU. In August 2015, Lumentum became an independent publicly-traded company through the distribution by JDSU to its stockholders of 80.1% of Lumentum’s outstanding common stock (the “Separation”).

Shares of Lumentum common stock are traded on NASDAQ under the symbol “LITE.” Following the Merger, shares of Lumentum common stock will continue to be traded on NASDAQ under the symbol “LITE.”

The principal executive offices of Lumentum are located at 400 North McCarthy Boulevard, Milpitas, California 95035, and Lumentum’s telephone number is (408) 546-5483. Additional information about Lumentum and its subsidiaries is included in documents incorporated by reference into this proxy statement/prospectus. See the section titled “Where You Can Find More Information” beginning on page 169 of this proxy statement/prospectus.

Oclaro, Inc.

Oclaro is one of the leading providers of optical components and modules for the long-haul, metro and data center markets. Leveraging more than three decades of laser technology innovation and photonics integration, Oclaro provides differentiated solutions for optical networks and high-speed interconnects driving the next wave of streaming video, cloud computing, application virtualization and other bandwidth-intensive and high-speed applications.

Oclaro was incorporated in Delaware in June 2004. On September 10, 2004, Oclaro became the publicly traded parent company of the Oclaro Technology Ltd (formerly Bookham Technology plc) group of companies, including Oclaro Technology Ltd, a limited company incorporated under the laws of England and Wales whose stock was previously traded on the London Stock Exchange and the NASDAQ National Market under the Bookham name. Effective January 3, 2011, Oclaro common stock was traded on the NASDAQ Global Select Market under the symbol “OCLR.”

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The principal executive offices of Oclaro are located at 225 Charcot Avenue, San Jose, California 95131, and Oclaro’s telephone number is (408) 383-1400. Additional information about Oclaro is included in documents incorporated by reference into this proxy statement/prospectus. See the section titled “Where You Can Find More Information” beginning on page 169 of this proxy statement/prospectus.

Prota Merger Sub, Inc.

Prota Merger Sub, Inc., or “Merger Sub,” is a direct wholly owned subsidiary of Lumentum and is a Delaware corporation. Merger Sub was formed on March 9, 2018, for the sole purpose of effecting the First Step Merger. In the First Step Merger, Merger Sub will be merged with and into Oclaro, with Oclaro surviving as a direct wholly owned subsidiary of Lumentum.

The principal executive offices of Merger Sub are located at 400 North McCarthy Boulevard, Milpitas, California 95035, and Merger Sub’s telephone number is (408) 546-5483.

Prota Merger, LLC

Prota Merger, LLC, or “Merger Sub LLC,” is a direct wholly owned subsidiary of Lumentum and is a Delaware limited liability company. Merger Sub LLC was formed on March 9, 2018, for the sole purpose of effecting the Second Step Merger. In the Second Step Merger, Oclaro will be merged with and into Merger Sub LLC, with Merger Sub LLC surviving as a direct wholly owned subsidiary of Lumentum.

The principal executive offices of Merger Sub LLC are located at 400 North McCarthy Boulevard, Milpitas, California 95035, and Merger Sub LLC’s telephone number is (408) 546-5483.

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SELECTED HISTORICAL CONSOLIDATED FINANCIAL DATA OF LUMENTUM

The following tables present selected historical consolidated financial data of Lumentum as of and for the fiscal years ended July 1, 2017, July 2, 2016, June 27, 2015, June 28, 2014, and June 29, 2013, and as of and for the nine-month periods ended March 31, 2018 and April 1, 2017. The consolidated financial statements of Lumentum have been presented in accordance with U.S. GAAP.

The selected consolidated financial data as of July 1, 2017 and July 2, 2016 and for each of the fiscal years in the three-year period ended July 1, 2017 are derived from Lumentum’s audited consolidated financial statements incorporated by reference into this proxy statement/prospectus. The selected consolidated financial data as of June 27, 2015 and June 28, 2014 and for the fiscal years ended June 28, 2014 and June 29, 2013 are derived from Lumentum’s audited consolidated financial statements that are not incorporated by reference into this proxy statement/prospectus. The selected consolidated financial data as of June 29, 2013 is derived from Lumentum’s unaudited consolidated financial statements that are not incorporated by reference into this proxy statement/prospectus.

The selected consolidated financial data of Lumentum as of and for the nine-month periods ended March 31, 2018 and April 1, 2017 have been derived from the unaudited consolidated interim financial information incorporated by reference into this proxy statement/prospectus, which, in the opinion of Lumentum’s management, includes all adjustments necessary to present fairly Lumentum’s results of operations and financial condition at the dates and for the periods presented. The results for the nine-month period ended March 31, 2018 are not necessarily indicative of the results of operations that you should expect for the entire year ending June 30, 2018, or any other period.

The financial information set forth below is only a summary that should be read in conjunction with the section titled “Risk Factors” beginning on page 57 of this proxy statement/prospectus and Lumentum’s consolidated financial statements, including the related notes, as well as the section titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations” contained in Lumentum’s Annual Report on Form 10-K/A for the fiscal year ended July 1, 2017, as amended, and the Quarterly Reports on Form 10-Q for the periods ended September 30, 2017, December 30, 2017 and March 31, 2018 that Lumentum previously filed with the SEC and that are incorporated by reference into this proxy statement/prospectus. Historical results are not necessarily indicative of any results to be expected in the future. See also the section titled “Where You Can Find More Information” beginning on page 169 of this proxy statement/prospectus for the location of information incorporated by reference in this proxy statement/prospectus.

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SELECTED HISTORICAL CONSOLIDATED FINANCIAL DATA OF OCLARO

The following tables present selected historical consolidated financial data of Oclaro as of and for the fiscal years ended July 1, 2017, July 2, 2016, June 27, 2015, June 28, 2014, and June 29, 2013, and as of and for the nine-month periods ended March 31, 2018 and April 1, 2017. The consolidated financial statements of Oclaro have been presented in accordance with U.S. GAAP.

The selected consolidated financial data as of July 1, 2017 and July 2, 2016 and for each of the fiscal years in the three-year period ended July 1, 2017 are derived from Oclaro’s audited consolidated financial statements contained in Oclaro’s Annual Report on From 10-K for the fiscal year ended July 1, 2017, which is incorporated by reference into this proxy statement/prospectus. The selected consolidated financial data as of June 28, 2014 and June 29, 2013 and for each of the fiscal years in the two-year period ended June 28, 2014 are derived from Oclaro’s audited consolidated financial statements contained in Oclaro’s other reports filed with the SEC, which are not included or incorporated by reference into this proxy statement/prospectus.

The selected consolidated financial data of Oclaro as of and for the nine-month periods ended March 31, 2018 and April 1, 2017 have been derived from Oclaro’s unaudited consolidated interim financial statements incorporated by reference into this proxy statement/prospectus, which in the opinion of Oclaro’s management, includes all adjustments necessary to present fairly Oclaro’s results of operations and financial condition at the dates and for the periods presented. The results for the nine-month period ended March 31, 2018 are not necessarily indicative of the results of operations that you should expect for the entire year ending June 30, 2018, or any other period.

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The financial information set forth below is only a summary that should be read in conjunction with the section titled “Risk Factors” beginning on page 57 of this proxy statement/prospectus and Oclaro’s consolidated financial statements, including the related notes, as well as the section titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations” contained in Oclaro’s Annual Report on Form 10-K for the fiscal year ended July 1, 2017 and the Quarterly Reports on Form 10-Q for the periods ended September 30, 2017, December 30, 2017 and March 31, 2018 that Oclaro previously filed with the SEC and that are incorporated by reference into this proxy statement/prospectus. Historical results are not necessarily indicative of any results to be expected in the future. See also the section titled “Where You Can Find More Information” beginning on page 169 of this proxy statement/prospectus for the location of information incorporated by reference in this proxy statement/prospectus.

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UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION

On March 11, 2018, Lumentum, Oclaro, Merger Sub and Merger Sub LLC entered into the Merger Agreement, pursuant to which Lumentum agreed to acquire Oclaro by way of a merger of Merger Sub with and into Oclaro, with Oclaro as the interim surviving corporation, followed as soon as practicable by a merger of Oclaro with and into Merger Sub LLC, with Merger Sub LLC continuing as the surviving entity and as a wholly owned subsidiary of Lumentum. Upon completion of the Merger, each share of Oclaro common stock issued and outstanding immediately prior to the effective time of the Merger will be converted into the right to receive $5.60 in cash without interest, and 0.0636 of a share of Lumentum common stock, subject to the conditions and restrictions set forth in the Merger Agreement.

The unaudited pro forma condensed combined balance sheet as of March 31, 2018 gives effect to the Merger, as if the Merger had been completed on March 31, 2018 and combines the unaudited condensed consolidated balance sheet of Lumentum as of March 31, 2018 with Oclaro’s unaudited condensed consolidated balance sheet as of March 31, 2018.

The unaudited pro forma condensed combined statements of operations for the year ended July 1, 2017 and the nine months ended March 31, 2018 give effect to the Merger as if it had occurred on July 3, 2016, the first day of Lumentum’s fiscal 2017, and combines the historical results of Lumentum and Oclaro. The unaudited pro forma condensed combined statement of operations for the fiscal year ended July 1, 2017 combines the audited consolidated statement of operations of Lumentum for the fiscal year ended July 1, 2017 with Oclaro’s audited consolidated statement of operations for the fiscal year ended July 1, 2017. The unaudited pro forma condensed combined statement of operations for the fiscal nine months ended March 31, 2018 combines the unaudited condensed consolidated statement of operations of Lumentum for the fiscal nine months ended March 31, 2018 with Oclaro’s unaudited condensed consolidated statement of operations for the fiscal nine months ended March 31, 2018.

The historical consolidated financial information has been adjusted in the unaudited pro forma condensed combined financial statements to give effect to pro forma events that are (i) directly attributable to the Merger, (ii) factually supportable, and (iii) with respect to the statements of operations, expected to have a continuing impact on the combined company’s results.

The unaudited pro forma condensed combined financial information presented is for informational purposes only and is not necessarily indicative of the financial position or results of operations that would have been realized if the Merger had been completed on the dates set forth above, nor is it indicative of future results or financial position of the combined company. Additionally, the final determination of the purchase price and the purchase price allocation, upon the completion of the Merger, will be based on Oclaro’s net assets acquired as of that date and will depend on a number of factors that cannot be predicted with certainty at this time. The unaudited pro forma condensed combined financial information does not reflect any anticipated synergies or dissynergies, operating efficiencies or cost savings that may result from the Merger or potential divestitures that may occur prior to, or subsequent to, completion of the Merger or any acquisition and integration costs that may be incurred. The pro forma adjustments, which Lumentum believes are reasonable under the circumstances, are preliminary and are based upon available information and certain assumptions described in the accompanying notes to the unaudited pro forma condensed combined financial information. Actual results and valuations may differ materially from the assumptions within the accompanying unaudited pro forma condensed combined financial information.

The transaction is being accounted for as a business combination using the acquisition method with Lumentum as the accounting acquirer in accordance with Accounting Standards Codification (“ASC”) Topic 805, Business Combinations (“ASC 805”). Under this method of accounting, the purchase price will be allocated to Oclaro’s assets acquired and liabilities assumed based upon their estimated fair values at the date of completion of the Merger. The process of valuing the tangible and intangible assets and liabilities of Oclaro

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immediately prior to the Merger, as well as evaluating accounting policies for conformity, is preliminary. The final valuation may materially change the allocation of the Merger Consideration, which could materially affect the fair values assigned to the assets and liabilities and could result in a material change to the unaudited pro forma condensed combined financial information. Refer to Note 2 of the “Notes to Unaudited Pro Forma Condensed Combined Financial Information” for more information on the basis of presentation. The pro forma adjustments are preliminary and have been made solely for the purpose of providing unaudited pro forma condensed combined financial statements prepared in accordance with the rules and regulations of the SEC.

The unaudited pro forma condensed combined financial information should be read in conjunction with:

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UNAUDITED PRO FORMA CONDENSED COMBINED BALANCE SHEET

AS OF MARCH 31, 2018

(in millions)