CIEN

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

Filed by the Registrant   ☒                             Filed by a party other than the Registrant   ☐

Check the appropriate box:

CIENA CORPORATION

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

EXPLANATORY NOTE

Ciena Corporation (the “Company”) is making this filing solely to replace the notice of internet availability of proxy materials (the “Notice”) the Company filed with the Securities and Exchange Commission (the “SEC”) on February 16, 2023 (the “Original Filing Date”) with respect to the Company’s 2023 Annual Meeting of Stockholders (the “Annual Meeting”). Due to a clerical error, an incorrect version of the Notice was inadvertently initially filed with the SEC. The correct version of the Notice, which is the version included in this filing, was mailed to Company stockholders on the Original Filing Date.

Your Vote Counts! CIENA CORPORATION 2023 Annual Meeting Vote by March 29, 2023 11:59 PM ET CIENA CORPORATION 7035 RIDGE ROAD HANOVER, MD 21076 D96346-P82461 You invested in CIENA CORPORATION and it’s time to vote! You have the right to vote on proposals being presented at the Annual Meeting. This is an important notice regarding the availability of proxy materials for the Annual Meeting of Stockholders to be held on March 30, 2023. Get informed before you vote View the Notice and Proxy Statement, Annual Report with Form 10-K online OR you can receive a free paper or email copy of the material(s) by requesting prior to March 16, 2023. If you would like to request a copy of the material(s) for this and/or future stockholder meetings, you may (1) visit www.ProxyVote.com, (2) call 1-800-579-1639 or (3) send an email to sendmaterial@proxyvote.com. If sending an email, please include your control number (indicated below) in the subject line. Unless requested, you will not otherwise receive a paper or email copy. For complete information and to vote, visit www.ProxyVote.com Control # Smartphone users Vote Virtually at the Meeting* Point your camera here and March 30, 2023 3:00 PM EST vote without entering a control number Virtually at: www.virtualshareholdermeeting.com/CIEN2023 *Please check the meeting materials for any special requirements for meeting attendance. V1.1

Vote at www.ProxyVote.com THIS IS NOT A VOTABLE BALLOT This is an overview of the proposals being presented at the upcoming stockholder meeting. Please follow the instructions on the reverse side to vote these important matters. Voting Items Board Recommends 1. Election of two Class II Directors: Nominees: 1a. Joanne B. Olsen For 1b. Gary B. Smith For 2. Ratification of the appointment of PricewaterhouseCoopers LLP as our independent registered public accounting firm for fiscal 2023. For 3. Advisory vote on our named executive officer compensation, as described in the proxy materials. For 4. Advisory vote on the frequency of future stockholder advisory votes on our named executive officer compensation. 1 Year NOTE: Such other business as may properly come before the Annual Meeting or any adjournment or postponement thereof. Prefer to receive an email instead? While voting on www.ProxyVote.com, be sure to click “Sign up for E-delivery”. D96347-P82461