As filed with the Securities and Exchange Commission on May 23, 2006

Registration No. 333-124347

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

POST-EFFECTIVE AMENDMENT NO. 3 TO

FORM S-1

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

FINISAR CORPORATION

(Exact name of Registrant as specified in its charter)

1389 Moffett Park Drive

Sunnyvale, California 94089

(408) 548-1000

(Address, including zip code, and telephone number, including area

code, of Registrant’s principal executive offices)

Jerry S. Rawls

Chief Executive Officer

Finisar Corporation

1308 Moffett Park Drive

Sunnyvale, California 94089

(408) 548-1000

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

Copies to:

      Approximate date of commencement of proposed sale to the public: As soon as practicable after the effective date of this Registration Statement.

      If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, check the following box:     o

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

      If this Form is a post-effective amendment filed pursuant to Rule 462(c) 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.     o

      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.     o

      If delivery of the prospectus is expected to be made pursuant to Rule 434 under the Securities Act, please check the following box.     o

EXPLANATORY NOTE

      This Post-Effective Amendment No. 3 to the Registration Statement on Form S-1, File No. 333-124347, is being filed with the Securities and Exchange Commission for the sole purpose of de-registering 1,659,279 shares of common stock not sold under the Registration Statement. Finisar Corporation hereby de-registers 1,659,279 shares of common stock.

SIGNATURES

      Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-1 and has duly caused this Post-Effective Amendment No. 3 to the Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Sunnyvale, State of California on May 23, 2006.

      Pursuant to the requirements of the Securities Act of 1933, this Post-Effective Amendment No. 3 to the Registration Statement has been signed by the following persons in the capacities and on the dates indicated: