Company: AAOI
Filing Date: 2025-06-02
Form Type: DEFA14A
Source: 0001104659-25-055505
Chunk: 0

Company: APPLIED OPTOELECTRONICS, INC.
Filing Date: 2025-06-02
Form: DEFA14A
Chunk 0
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<div align='center'>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 (Amendment No. )</div>

Filed by the Registrant x

Filed by a Party other than the Registrant ¨

Check the appropriate box:

| ¨ | Preliminary Proxy Statement |

| ¨ | Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) |

| ¨ | Definitive Proxy Statement |

| x | Definitive Additional Materials |

| ¨ | Soliciting Material under §240.14a-12 |

<div align='center'>APPLIED OPTOELECTRONICS, INC.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than
the Registrant)</div>

Payment of Filing Fee (Check the appropriate box):

| x | No fee required. |

| ¨ | Fee paid previously with preliminary materials. |

| ¨ | Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11 |

<div align='center'>SUPPLEMENT NO. 1 TO PROXY STATEMENT FOR

THE ANNUAL MEETING OF STOCKHOLDERS

TO BE HELD ON JUNE 12, 2025

June 2, 2025</div>

Explanatory Note

This proxy statement supplement
should be read together with the definitive proxy statement (the “Proxy Statement”) of Applied Optoelectronics, Inc.
(the “Company”) filed with the Securities and Exchange Commission on April 28, 2025 related to the Company’s 2025
Annual Meeting of Stockholders (the “Annual Meeting”) to be held on June 12, 2025, which is incorporated herein by reference.
The purpose of this supplement is to update information contained in the Proxy Statement relating to the following:

| · | The withdrawal of Proposal No. 4 — Approval of Amendment of our Amended and Restated                                       
 Certificate of Incorporation, as amended (the “Certificate of Incorporation”), to Clarify the Voting Standard that Applies 
 to Certain Future Amendments (the “Withdrawn Proposal No. 4”).                                                             |

| · | The update of certain information