<PAGE>

                                                                 Exhibit 10.20

                                 AMENDMENT NO. 1
                                       TO
                               SUBLEASE AGREEMENT

This amendment ("Amendment") is entered into this 14th day of April 2000 and
modifies the Sublease Agreement by and between Wyse Technology Inc.
(hereinafter "Sublessor") and Oplink Communications Inc. (hereinafter
"Sublessee") and Wyse Technology Investments Inc. (hereinafter "Landlord")
which is dated 29 February 2000.

The provisions of this Amendment are intended to modify certain provisions of
the Sublease. Where the provisions of the Amendment are specifically stated
and differ from those in the Sublease, the provisions of the Amendment shall
control. All other terms and conditions remain unchanged.

For consideration of additional rent, covenants, agreements and conditions
herein contained, Sublessor, Sublessee and the Landlord hereby agree as
follows:

         1.       SUBLEASED PREMISES. The Sublease consists of certain
                  premises which constitute approximately 62,023 square feet
                  of the building located at 3475 North First St., San Jose,
                  CA 95134 (hereinafter referred to as "Premises") which are
                  a portion of the property ("Campus") which is the subject
                  of that certain Lease dated March 19, 1993 (and as amended
                  and restated) between Sublessor and Landlord.

                  The amendment shall add the following space to the
                  Premises: Approximately 16,059 square feet of the first
                  floor of the building located at 3471 N. First St. San
                  Jose, CA 95134. Hereafter, the term Premises shall be
                  amended to include this additional space.

Sublessor hereby subleases to Sublessee, and Sublessee hereby subleases from
Sublessor, for the term and upon conditions herein after set forth, the added
space as described above and as shown on the drawing attached hereto as
Exhibit A and incorporated herein by this reference.

The total Subleased Premises now contains approximately 77,523 rentable
square feet. Landlord hereby provides his unqualified consent to this
Amendment of the Sublease.

         2.       TERM. Subject to the terms and conditions set forth herein,
                  the term of Amendment shall commence on or about April 14,
                  2000 (the "Commencement Date"), and shall terminate
                  contemporaneously with the Sublease on February 28, 2005,
                  except that it is understood and agreed by the Sublessee
                  and the Sublessor that the right and interest of Sublessee
                  under this Sublease are derivative of those of Sublessor
                  under the Lease between Sublessor Landlord and not any
                  greater than such rights and interest of Sublessor as to
                  the Subleased Premises.

         3.       RENEWAL OPTION. The Renewal Option set forth in the
                  Sublease also applies to the Amendment.

         4.       USE. Sublessee is permitted to use the Subleased Premises
                  for office space only.


                                      1.
<PAGE>

         5.       RENT.

                  (a)      During the term of this Sublease, and commencing
                           on the Commencement Date Sublessee covenants and
                           agrees to pay to Sublessor $1.90 per rentable
                           square foot (RSF) per month as Base Rate for the
                           additional premises, without previous notice or
                           demand. The monthly total monthly rent, therefore,
                           will increase by the amount of $30, 512.10 from
                           $108,540.25 to a combined total of $ 139052.35.
                           The rent payment shall be delivered to Sublessor
                           on or before the first day of each calendar month
                           during the term of the sublease hereof, with the
                           first such monthly installment to be paid upon the
                           signature of the Sublease.

                  (b)      If the Commencement Date shall occur on a date
                           other than the first day of a calendar month,
                           Sublessee shall pay to Sublessor on the first day
                           of the month next succeeding the Commencement Date
                           a sum equal to one-thirtieth (1/30) of the months
                           rent installment of the Base Rate set forth above,
                           multiplied by the number of days of the calendar
                           month in which the Commencement Date occurred.
                           This pro-rata payment of the Base Rate for the
                           portion of the month of the Commencement Date
                           shall be in addition to the monthly installment of
                           the Base Rate applicable to that month.

                  (c)      Increases to Base Rent. At the end of the 2nd year
                           of the term, the rent for this additional space
                           shall increase by 3%. The base rate shall then be
                           $1.96 per RSF. Thereafter, the base rent shall
                           remain unchanged for the balance of the term.

                  (d)      As security for Sublessee's faithful performance
                           under the Sublease, Sublessee shall upon execution
                           of the Sublease increase the sum of the security
                           deposit by $ 30,512 (equaling one month's Base
                           Rate) for security deposit.

                  (e)      The rent for the space added by this Amendment is
                           "gross" in that utilities and property taxes are
                           included.

         6.       CONDITION OF ADDED SPACE. Sublessee hereby agrees to accept
                  the added space on an "as is", "as built" condition on the
                  Commencement Date of the term of this Sublease, it being
                  understood and agreed that Sublessor makes no warranties,
                  express or implied, as to this space including by way of
                  example, and not limitation, any warranties of suitability,
                  fitness for purpose of use or habitability, except that
                  Sublessor will make it available to Sublessee on or before
                  14 April 2000.

         7.       UTILITIES. Included in the Base Rent for the added space
                  leased under this Amendment.

         8.       Each of the parties hereby represents that it has not
                  obtained the services of a real estate broker or agent for
                  the purposes of leasing the Subleased Premises and that


                                       2.
<PAGE>

                  it will indemnify and hold harmless the other parties from
                  such claims in the event that any other party established a
                  right derived from such indemnifying party to receive
                  commissions or any payment as a consequence of this
                  Sublease. Any or all brokers fees are the subject of
                  separate agreement(s) and Sublessee acknowledges that
                  neither Sublessor or Landlord have any obligation
                  thereunder for the payment of any fees whatsoever.

In witness whereof, the parties hereto have caused this instrument to be
executed in triplicate as of the date first written above.

SUBLESSEE                               SUBLESSOR
OPLINK COMMUNICATIONS INC.              WYSE TECHNOLOGY INC.



BY   /s/ Joseph Liu                     BY:  /s/ Douglas Chance
  --------------------------------         --------------------------------


   Joseph Liu                           Douglas Chance
----------------------------------      -----------------------------------
(Print or type name)                    (Print or type name)

   CEO                                  President and CEO
----------------------------------      -----------------------------------
(Title)                                 (Title)

   04/10/00                             14 April 2000
----------------------------------      -----------------------------------
(Date)                                  (Date)




LANDLORD
WYSE TECHNOLOGY INVESTMENTS INC.

BY:   /s/ Douglas Chance
   -------------------------------


Douglas Chance
----------------------------------
(Print or type name)

President
----------------------------------
(Title)

14 April 2000
----------------------------------
(Date)


                                       3.
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                                    EXHIBIT A
                     DRAWING OF ADDED SPACE, BUILDING THREE

                                   (attached)
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                                  [FLOOR PLAN]