Exhibit 10.8.6
 
            SIXTH AMENDMENT TO
            PURCHASE AND SALE AGREEMENT
            AND PRELIMINARY ESCROW INSTRUCTIONS
[Portion of DiCon Fiberoptics Inc. Land, Regatta Boulevard, Richmond,
California]

This Sixth Amendment to Purchase and Sale Agreement and Preliminary Escrow
Instructions (the "Sixth Amendment") is entered into as of December 14, 2005,
between DICON FIBEROPTICS, INC., a California corporation ("Seller") and PULTE
HOME CORPORATION, a Michigan corporation ("Buyer").
RECITALS

A.  
Seller and Buyer entered into a Purchase and Sale Agreement and Preliminary
Escrow Instructions as of February 27, 2004, a First Amendment to Purchase and
Sale Agreement and Preliminary Escrow Instructions as of March 1, 2004, a Second
Amendment to Purchase and Sale Agreement and Preliminary Escrow Instructions as
of April 29, 2004, a Third Amendment to Purchase and Sale Agreement and
Preliminary Escrow Instructions as of February 27, 2005, a Fourth Amendment to
Purchase and Sale Agreement and Preliminary Escrow Instructions as of July 27,
2005, and a Fifth Amendment to Purchase and Sale Agreement and Preliminary
Escrow Instructions as of November 17, 2005 (collectively, the "Agreement").

B.  
Seller and Buyer desire to amend and restate certain provisions of the Agreement
as provided in this Sixth Amendment.

The parties agree as follows:
 
                                AGREEMENT

1.  
Section 8.1 of the Agreement is hereby amended by inserting the words "and live
work" on line two thereof after the word "detached" and before the word "homes".

2.  
Section 10.2 of the Agreement is hereby amended and restated in its entirety to
read as follows:

"10.2 Buyer's Covenants.

10.2.1  
Utilities. Within twelve (12) months after the Close of Escrow Buyer, at Buyer's
cost and expense (including any fees) and subject to the approval of Seller,
shall complete the design and engineering work and the construction work for the
separation and the relocation of all utility services and all fire lines and
fire lanes serving the Remaining Property and running over, under or across the
Purchase Property, including the granting of new utility easements benefiting
the Remaining Property and running over, under and across the Purchase Property
and the installation of a new fire hydrant on the southeast corner of the
Remaining Property. All deposits for utilities made by Seller and all refunds
due from utilities shall be the property of Seller. Buyer shall be responsible
for any required replacement of deposits. Seller shall release old utility
easements that have been replaced by new utility easements pursuant to this
Section 10.2.1 after the completion of the construction work on the utility
services using such new utility easements.

10.2.2  
Sanitary Sewer. Within twelve (12) months after the Close of Escrow Buyer, at
Buyer's cost and expense (including any fees) and subject to the approval of
Seller and with the cooperation of Seller, shall cause the City to accept
responsibility for the construction, maintenance, repair and replacement of the
existing sanitary sewers lying within the 10' private sanitary sewer easement
and the 10' sanitary sewer easement, running from the boundary line of the
Purchase Property and the Remaining Property along the southern boundary of the
Purchase Property to Marina Bay Parkway and as shown on Parcel Map MS 754-01
recorded on December 24, 2001 in Book 182 of Maps at pages 38-41, Contra Costa
County Official Records and on the Acceptable Parcel Map, and the connection
between the sewers.

10.2.3  
Fence. Within ten (10) days after the Close of Escrow Buyer, at Buyer's cost and
expense (including any fees) and subject to the approval of Seller, shall
install a temporary chain link fence separating the Purchase Property and the
Remaining Property.

10.2.4  
New Parking Area. Within twelve (12) months after the Close of Escrow, for the
areas to be designated by Seller on Lot 2, Buyer, at Buyer's cost and expense
(including any fees) and subject to the approval of Seller, shall complete the
design and engineering work and the construction work for new parking areas of
not less than the greater of (i) three hundred (300) parking spaces or (ii) the
number of parking spaces required by the City. The work for the new parking
areas shall include, grading, paving, stripping parking spaces, landscaping,
lighting, irrigation lines, fire lines, and fire lanes.

10.2.5  
Transformer; Utilities. Buyer shall not, and shall not permit any contractor or
subcontractor or any other person to (a) use any electrical service from the
existing transformer serving the Property, or (b) interfere with any utility
service accessing the Remaining Property through the Purchase Property.

10.2.6  
Grading. Buyer shall not change the grade of the Purchase Property to a grade
that will adversely affect the use of, or the storm water drainage to or from,
the Remaining Property.

10.2.7  
Submission of Plans. Buyer shall submit the plans and specifications for the
design and engineering work required under this Section 10.2 to Seller at least
ten (10) Business Days prior to the commencement of the work pursuant to such
plans and specifications so that Seller may inform Buyer whether the design and
engineering work meets with Seller¡¦s approval.

10.2.8  
"As Built" Plans. Buyer shall furnish Seller with two hard copies and one soft
copy of the "as built" plans and specifications for the work performed pursuant
to this Section 10.2 as soon as such work is completed.

10.2.9  
Governmental Approvals. Buyer, at Buyer's cost and expense (including any fees),
shall obtain in a timely manner all governmental approvals required in
connection with the work contemplated by this Section 10.2. Buyer shall deliver
to Seller the original or a copy of each such approval as soon as obtained by
Buyer.

10.2.10  
Notice of Completion. With respect to any contract made by Buyer for the work to
be performed under this Section 10.2, after completion of such work under such
contract, Buyer shall execute and record, in the official records of the County
of Contra Costa, a Notice of Completion meeting the requirements of California
Civil Code Section 3093.

10.2.11  
Insurance. Buyer shall purchase and maintain insurance protecting Seller from
claims which may arise out of or result from the work performed in connection
with this Section 10.2, including liability, property damage and workmen¡¦s
compensation. All such insurance shall name Seller as insured or additional
insured, shall be issued by an insurer or insurers satisfactory to Seller, shall
be written for not less than the limits of liability specified on Exhibit G
hereto, and shall be otherwise satisfactory to Seller.

Certificates of the insurance policies required under this Section 10.2.11 shall
be delivered to Seller not less than thirty five (30 5) /s/ SK /s/ HSL days
prior to the commencement of the work to be performed under this Section 10.2."

3.  
Section 11.1 of the Agreement is hereby amended by adding "SECTION 8," on lines
three and ten thereof after "OBLIGATIONS UNDER" and before "SECTION 10.2".

 
Seller's Initials  /s/ HSL              Buyer's Initials /s/ SK

4.  
Section 11.2 of the Agreement is hereby amended by adding "SECTION 8," on line
two thereof after "OBLIGATIONS UNDER" and before "SECTION 10.2".

Seller's Initials  /s/ HSL  Buyer's Initials /s/ SK

5.  
Except as amended and restated by this Sixth Amendment, all terms, conditions
and provisions of the Agreement shall remain in full force and effect.

6.  
This Sixth Amendment may be executed by the different parties hereto on separate
counterparts each of which, when so executed, shall be deemed an original but
all such counterparts shall constitute but one and the same agreement.

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IN WITNESS HEREOF, the parties hereto have executed this Sixth Amendment as of
the date first above written.

Seller:                                    Buyer:

DICON FIBEROPTICS, INC.,                        PULTE HOME CORPORATION
a California corporation                     a Michigan corporation

By: /s/ Ho-Shang Lee                     
                                                                           By:
/s/ J. Steven Kalmbach       

Name:  Ho-Shang Lee, Ph.D.              Name:  J. Steven Kalmbach
Its: President and CEO                                                       
Its: Division President
 
                            Acceptance by Escrow Holder

CHICAGO TITLE COMPANY hereby acknowledges that it has received originally
executed counterparts or a fully executed original of the foregoing Sixth
Amendment to Purchase and Sale Agreement and Preliminary Escrow Instructions and
agrees to act as Escrow Agent thereunder and to be bound by and perform the
terms thereof as such terms apply to Escrow Agent.

CHICAGO TITLE COMPANY

By: _______________________________      

Name:  Laurie J. Edwards
Its: Assistant Vice President
Date of Execution: ____________________    

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EXHIBIT G

INSURANCE
Liability       $5,000,000

Property damage     $5,000,000

Workers' compensation  $2,000,000

Employer's practice liability   $1,000,000