EXHIBIT 10.3

                                LIMITED GUARANTY

      LIMITED GUARANTY (the "Guaranty"), dated as of December 20, 2000 (the
"Effective Date"), by Tyco International Group S.A., a company incorporated
under the laws of Luxembourg (the "Guarantor"), in favor of Fleet National Bank,
a national banking association, and its foreign branches (the "Bank"), in
consideration of the Bank providing certain credit facilities as specified in
Section 1 below (the "Financial Accommodation") to Fibercore, Inc., (the
"Debtor"), a corporation that is partially owned by an affiliate of the
Guarantor.

      WHEREAS, in order to induce the Bank to provide the credit facilities to
the Debtor under the Financial Accommodation, the Guarantor has agreed, subject
to the limitations set forth in Section 3 below, to guarantee all indebtedness
and other obligations owing by the Debtor to the Bank pursuant to the Financial
Accommodation;

      NOW, THEREFORE, in consideration of the promises contained herein and for
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the Guarantor agrees as follows:

            1. FINANCIAL ACCOMMODATION. As used herein, the term "Financial
Accommodation" means the credit facility in the maximum principal amount of
$10,000,000.00 extended by the Bank to the Debtor pursuant to that certain Loan
Agreement dated as of December 20, 2000 (the "Credit Agreement") and the
revolving credit note and other agreements referred to therein or relating
thereto, (together, the "Loan Documents"), as the same may be amended from time
to time, but does not include any loan or other form of credit extended by the
Bank to the Debtor other than under the Loan Documents.

            2. GUARANTY OF PAYMENT AND PERFORMANCE. The Guarantor hereby
guarantees to the Bank, subject to the limitations set forth in Section 3 below,
the due and punctual payment of all funds owed by the Debtor to the Bank
pursuant to and in accordance with the terms and conditions of the Loan
Documents (the "Obligations") and agrees to pay the Obligations to the Bank on
first written demand therefor, in accordance with Section 12 below, without any
withholding, deduction or setoff for any reason or on any accounts whatsoever;
provided that the Bank shall not demand any of the Obligations until there has
been default by the Debtor on such Obligations and notice of such default has
been received by the Debtor and the Guarantor and any applicable time or grace
periods have expired. Except for the notice and time or grace periods
requirements set forth in the immediately preceding sentence, such Guaranty is
in no way conditional upon any requirement that the Bank first attempt to
collect any of the Obligations from the Debtor or resort to any security or
other means of obtaining payment of the Obligations. Subject to the limitations
set forth in Section 3 below, payments by the Guarantor hereunder may be
required by the Bank on any number of occasions.

            3. GUARANTY LIMITATIONS. Notwithstanding anything to the contrary
contained or implied in this Guaranty, the aggregate actual and contingent
liability of the Guarantor under this Guaranty shall be limited to a maximum
principal amount of USD $10,000,000 (Ten Million U.S. Dollars) plus interest,
costs and charges upon this maximum principal amount, in accordance with the
terms and conditions of the Loan Documents, without any withholding, deduction
or set off for any reason or account whatsoever. In no event shall the Guarantor
be liable under this Guaranty for any amounts advanced by the Bank on or after
the date on which the Bank first demands payment by the Guarantor (the "Demand
Date"). The limitation in the immediately preceding sentence shall not apply to
(i) advances made on or after the Demand Date to fund payment of letters of
credit issued before such Demand Date under the Credit Agreement for the account
of the Debtor or (ii) interest, fees, costs and other expenses that accrue on or
after the Demand Date under the terms of the Loan Documents on (x) advances made
before the Demand Date or (y) advances made after the Demand Date to fund
payment of letters of credit issued before the Demand Date.

            4. WAIVERS BY GUARANTOR. The Guarantor (i) agrees that the
Obligations will be paid and performed strictly in accordance with their
respective terms regardless of any law, or any regulation or order now or
hereafter in effect in any jurisdiction affecting any of such terms or the
rights of the Bank with respect thereto, and (ii) except as specifically
provided herein, waives presentment, demand, protest, notice of acceptance,
notice of Obligations incurred and all other notices of any kind, all defenses
that may be available by virtue of any valuation, stay, moratorium law or other
similar law now or hereafter in effect, any right to require the marshalling of
assets of the Debtor, and all suretyship defenses generally. Without limiting
the generality of the foregoing, the Guarantor agrees to the provisions of any
instrument evidencing, securing or otherwise executed by the Debtor in
connection with the Financial Accommodation or any Obligation and, except as
specifically provided herein, the Guarantor agrees that the Obligations of the
Guarantor hereunder shall not be released or discharged, in whole or in part, or
otherwise affected by (i) the failure of the Bank to assert any claim or demand
or to enforce any right or remedy against the Debtor; (ii) any extensions or
renewals of the Financial Accommodation or any Obligation; (iii) any
rescissions, waivers, amendments or modifications of any of the terms or
provisions of any agreement evidencing, securing or otherwise executed in
connection with the Financial Accommodation or any Obligation; (iv) the
substitution or release of the Debtor or any other person primarily or
secondarily liable for any Obligation (other than as a result of the payment of
all the Obligations in accordance with the terms and conditions under which the
Financial Accommodation was provided); (v) the adequacy of any rights the Bank
may have against any collateral or other means of obtaining repayment of the
Obligations; (vi) the impairment of any collateral securing the Obligations,
including the failure to perfect or preserve any rights the Bank might have in
such collateral or the substitution, exchange, surrender, release, loss or
destruction of any such collateral; or (vii) any other act or omission that
might in any manner or to any extent vary the risk of the Guarantor or otherwise
operate as a release or discharge of the Guarantor, all of which may be done
without notice to the Guarantor.

            5. UNENFORCEABILITY OF OBLIGATIONS AGAINST DEBTOR. If for any reason
the Debtor has no legal existence or is under no legal obligation to discharge
any of the Obligations, or if any of the Obligations have become unrecoverable
from the Debtor by operation of law or for any other reason, including any
declaration by any court of law or equity that any of the Obligations are void
or unenforceable, this Guaranty shall nevertheless be binding on the Guarantor
to the same extent as if the Guarantor at all times had been the principal
obligor on all such Obligations. In the event that acceleration of the time for
payment of the Obligations is stayed upon the insolvency, bankruptcy or
reorganization of the Debtor, or for any other reason, all such amounts
otherwise subject to acceleration in accordance with the terms and conditions
under which the Financial Accommodation was provided shall be immediately due
and payable by the Guarantor.

            6. WITHHHOLDING, ETC. In the event that the Guarantor is required by
statute or law to make any withholding, deduction or setoff in respect of any
payment made or to be made by the Guarantor hereunder, the Guarantor will, in
addition to such amount, also pay to the Bank such sum as may be necessary to
give the Bank such sum as it would have been entitled to under the terms of this
Guaranty but for such withholding, deduction or setoff.

            7. SUBROGATION. The Guarantor shall be subrogated to all rights of
the Bank against the Debtor in respect of amounts paid by the Guarantor pursuant
to the provisions of this Guaranty; provided however that the Guarantor shall
not be entitled to enforce or to receive any payments arising out of, or based
upon, such right of subrogation until all of the Obligations shall have been
paid and discharged in full.

            8. TERMINATION; REINSTATEMENT. This Guaranty shall remain in full
force and effect until the earlier of (a) payment in full of all principal,
interest, fees or other amounts then owing under the Credit Agreement and the
other Loan Documents, and (b) receipt by Bank of written notice of the
Guarantor's intention to discontinue this Guaranty, notwithstanding any
intermediate or temporary payment or settlement of the whole or any part of the
Obligations. No notice provided in clause (b) shall be effective unless received
and acknowledged by an officer of the Bank at its head office or at the branch
of the Bank where this Guaranty is given. No such notice under clause (b) shall
affect any rights of the Bank or of any affiliate hereunder including, without
limitation, the rights set forth in Sections 4 and 7, with respect to
Obligations incurred prior to the receipt of such notice or Obligations incurred
pursuant to any contract or commitment in existence prior to such receipt, and
all checks, drafts, notes, instruments (negotiable or otherwise) and writings
made by or for the account of the Debtor and drawn on the Bank or any of its
agents purporting to be dated on or before the date of receipt of such notice,
although presented to and paid or accepted by the Bank after that date, shall
form part of the Obligations. This Guaranty shall continue to be effective or be
reinstated, notwithstanding any such notice, if at any time any payment made or
value received with respect to an Obligation is rescinded or must otherwise be
returned by the Bank upon the insolvency, bankruptcy or reorganization of the
Debtor, or otherwise, all as though such payment had not been made or value
received.

            9. RELEASE. Upon delivery to the Bank of a standby letter of credit
drawn on a United States bank with at least $75,000,000,000.00 in assets and a
long term unsecured credit rating of AA or higher by Standard & Poor's Rating
Group or Aa2 or higher by Moody's Investor's Service, Inc., such letter of
credit to be in an amount equal to 110% of the maximum amount of the then
available Financial Accommodation, the Bank shall release the Guarantor from all
obligations under this Guaranty, whereupon this Guaranty shall automatically
become void and of no further effect. Nothing in this Section 9 is intended or
shall be construed to limit the Bank's right, in its sole discretion, to release
this Guaranty under any other circumstances it deems appropriate. Once this
Guaranty has been released, pursuant to this Section 9, by the Bank, it cannot
be reinstated pursuant to Section 8.

            10. AMENDMENTS AND WAIVERS. No amendment or waiver of any provision
of this Guaranty nor consent to any departure by the Guarantor therefrom shall
be effective unless the same shall be in writing and signed by the Bank. No
failure on the part of the Bank to exercise, and no delay in exercising, any
right hereunder shall operate as a waiver thereof, nor shall any single or
partial exercise of any right hereunder preclude any other or further exercise
thereof or the exercise of any other right.

            11. GOVERNING LAW. This Guaranty shall be governed by, and construed
in accordance with, the laws of the State of New York without regard to the
conflict-of-laws principles thereof.

            12. NOTICES: All Notices, communications and distributions hereunder
shall be given or made to the intended recipient at the address specified below,
or at such other address as the addressee may hereafter specify for the purpose
by written notice to the other party hereto. Such Notices and other
communications (including, without limitation, any modifications of, or waivers
or consents under, this Agreement) shall be given or made in writing and may be
delivered by hand, by overnight courier, by facsimile, or by first-class mail
(return receipt requested). All such Notices and other communications shall be
deemed to have been duly given (a) if delivered by hand, overnight courier or
first-class mail (return receipt requested), on the date of delivery; and (b) if
transmitted by facsimile (with receipt confirmed by machine), on the date of
transmission if the same is a Business Day or, if not a Business Day, on the
first Business Day after the date of transmission. For the purposes of this
Guaranty, a Business Day is any day other than a Saturday, Sunday or any other
day on which banking institutions are authorized or required by law, executive
order or governmental decree to be closed in Luxembourg, New York or
Massachusetts.

To the Guarantor:
Tyco International Group S.A.
6, avenue Emile Reuter
Second Floor
L-2420 Luxembourg
Attention: Richard W. Brann
Telecopier: (011-352) 464-350

With copies to:

Tyco International (US) Inc.
One Tyco Park
Exeter, NH 03833
Attn: Chief Corporate Counsel

Fax: (603) 778-2823


Wilmer, Cutler & Pickering
2445 M Street, NW
Washington, DC  20037
Attention: Meredith Cross
Telecopier: (202) 663-6363

To the Bank:
Fleet National Bank
100 Federal Street
Boston, Massachusetts 02110
Attention: Senior Commercial Loan Officer/Massachusetts

With copies to:

Fleet National Bank
100 Front Street
Worcester, Massachusetts 01608
Attention: Senior Commercial Loan Officer

and

Bowditch & Dewey, LLP
311 Main Street
Worcester, Massachusetts  01608
Attention:  George W. Tetler III, Esquire

            13. JURY TRIAL WAIVER. THE GUARANTOR AND THE BANK (BY ACCEPTANCE OF
THIS GUARANTY) MUTUALLY HEREBY KNOWINGLY, VOLUNTARILY AND INTENTIONALLY WAIVE
THE RIGHT TO A TRIAL BY JURY IN RESPECT OF ANY CLAIM BASED HEREON, ARISING OUT
OF, UNDER OR IN CONNECTION WITH THIS GUARANTY OR ANY OTHER FINANCING INSTRUMENTS
EXECUTED OR CONTEMPLATED TO BE EXECUTED IN CONNECTION HEREWITH OR ANY COURSE OF
CONDUCT, COURSE OF DEALINGS, STATEMENTS (WHETHER VERBAL OR WRITTEN) OR ACTIONS
OF ANY PARTY RELATED HERETO, INCLUDING, WITHOUT LIMITATION, ANY COURSE OF
CONDUCT, COURSE OF DEALINGS, STATEMENTS OR ACTIONS OF THE BANK RELATING TO THE
ADMINISTRATION OF THIS GUARANTY AND THE OBLIGATIONS GUARANTEED HEREBY OR
ENFORCEMENT OF THE FINANCING INSTRUMENTS, AND AGREE THAT NEITHER PARTY WILL SEEK
TO CONSOLIDATE ANY SUCH ACTION WITH ANY OTHER ACTION IN WHICH A JURY TRIAL
CANNOT BE OR HAS NOT BEEN WAIVED. EXCEPT AS PROHIBITED BY LAW, THE GUARANTOR
HEREBY WAIVES ANY RIGHT IT MAY HAVE TO CLAIM OR RECOVER IN ANY LITIGATION ANY
SPECIAL, EXEMPLARY, PUNITIVE OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES OTHER THAN,
OR IN ADDITION TO, ACTUAL DAMAGES. THE GUARANTOR CERTIFIES THAT NO
REPRESENTATIVE, AGENT OR ATTORNEY OF THE BANK HAS REPRESENTED, EXPRESSLY OR
OTHERWISE, THAT THE BANK WOULD NOT, IN THE EVENT OF LITIGATION, SEEK TO ENFORCE
THE FOREGOING WAIVER. THIS WAIVER CONSTITUTES A MATERIAL INDUCEMENT FOR THE BANK
TO ACCEPT THIS GUARANTY AND FURNISH FINANCIAL ACCOMMODATIONS TO THE CUSTOMER.

            14. ENTIRE AGREEMENT. This Guaranty constitutes the entire agreement
of the Guarantor with respect to the matters set forth herein.

            15. REMEDIES CUMULATIVE. The rights and remedies herein provided are
cumulative and not exclusive of any remedies provided by law or any other
agreement, and this Guaranty shall be in addition to any other guaranty of the
Obligations.

            16. SEVERABILITY. The invalidity or unenforceability of any one or
more clauses of this Guaranty shall not affect the validity or enforceability of
its remaining provisions.

            17. HEADINGS. The captions herein are for the ease of reference only
and shall not affect the meaning of the provisions hereof.

      IN WITNESS WHEREOF, the Guarantor has caused this Guaranty to be executed
and delivered by its duly authorized officer as of the date first above written.

The Guarantor:

TYCO INTERNATIONAL GROUP S.A.

By:  ______________________________
       Richard W. Brann
       Managing Director

Agreed to and Accepted:



FLEET NATIONAL BANK


By:   _____________________________
[NAME]
[TITLE]