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                                                                     EXHIBIT 5.1

                      [MORRISON & FOERSTER LLP LETTERHEAD]

                               February 12, 2001


JDS Uniphase Corporation
210 Baypointe Parkway
San Jose, California 95134

Ladies and Gentlemen:

     At your request, we have examined the Registration Statement on Form S-4,
including the proxy statement-prospectus forming a part thereof, filed by you
with the Securities and Exchange Commission on February 12, 2001 (the
"Registration Statement"), in connection with the registration under the
Securities Act of 1933, as amended, of 2,527,532 shares of your common stock,
$.001 par value per share (the "Stock"). The Stock will be issued to the former
stockholders of SDL, Inc. ("SDL"), a Delaware corporation, pursuant to the terms
of that certain Agreement and Plan of Reorganization and Merger, dated as of
July 9, 2000, by and among you, K2 Acquisition, Inc., a Delaware corporation and
your wholly-owned subsidiary, and SDL (the "Merger Agreement"). As counsel to
the Company and in connection with this opinion, we have examined all
proceedings taken by you in connection with the registration of the Stock.

     It is our opinion that the Stock, which is being issued by you in exchange
for the shares of common stock of SDL pursuant to the Merger Agreement, when
issued in the manner described in the Registration Statement will be legally and
validly issued, fully paid and nonassessable.

     We consent to the use of this opinion as an exhibit to the Registration
Statement and further consent to all references to us in the Registration
Statement and any amendments thereto. In giving this consent, we do not thereby
admit that we are in the category of persons whose consent is required under
Section 7 of the Securities Act of 1933, as amended.

                              Very truly yours,

                              /s/ MORRISON & FOERSTER LLP