Document:

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                                                                   EXHIBIT 10.33

     THIS NOTE AND THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED
     UNDER THE SECURITIES ACT OF 1933, AND HAVE BEEN ACQUIRED FOR INVESTMENT AND
     NOT WITH A VIEW TO, OR IN CONNECTION WITH, THE SALE OR DISTRIBUTION
     THEREOF. NO SUCH SALE OR DISTRIBUTION MAY BE EFFECTED WITHOUT AN EFFECTIVE
     REGISTRATION STATEMENT RELATED THERETO OR AN OPINION OF COUNSEL ACCEPTABLE
     TO THE COMPANY THAT SUCH REGISTRATION IS NOT REQUIRED UNDER THE SECURITIES
     ACT OF 1933.

                           CONVERTIBLE PROMISSORY NOTE

$5,100,000                                                       August 13, 2003
Oxford, Massachusetts

FOR VALUE RECEIVED, IPG PHOTONICS CORPORATION, a Delaware corporation ("Maker"),
promises to pay to JDS UNIPHASE CORPORATION, a Delaware corporation ("Holder"),
the principal sum of FIVE MILLION, AND ONE HUNDRED THOUSAND DOLLARS ($5,100,000)
as provided below. This Note is subject to the following terms and conditions:

1.   Maturity

Principal outstanding shall be due and payable no later than the third
anniversary date of the date of original issuance of this Note (the "Maturity
Date").

2.   Payments

Maker shall make payments in lawful money of the United States of America and in
immediately available funds. The outstanding principal owing from time to time
hereunder will not bear interest. All payments under this Note shall be made to
Holder at JDS Uniphase Corporation, 1768 Automation Parkway, San Jose,
California 95131, ATTN: General Counsel, or at such other address as Holder
shall direct Maker in writing. This Note may be prepaid in whole or in part,
without penalty, at the option of Maker and without the consent of Holder.

3.   Conversion

     (a) This Note shall be convertible, in whole or in part, into shares of
fully paid and non-assessable shares of Series D Convertible Preferred Stock,
par value $.0001 per share, of Maker ("Preferred Stock") as follows: (i) at any
one or more times prior to the Maturity Date, the unpaid principal amount of
this Note shall be convertible at the option of Maker, in whole or part, and
(ii) immediately prior to the occurrence of a Change of Control (as hereinafter
defined) the unpaid principal amount of this Note shall be convertible at the
option of Holder; each such conversion without payment of any additional
consideration therefor, into that number of shares of Preferred Stock as is
determined by dividing the unpaid principal balance of this Note (or elected
portion thereof with respect to a conversion in part) by the Conversion Price in
effect at the time of such conversion. The "Conversion Price" shall initially be
$1.90 and shall be subject to adjustment (in order to adjust the number of
shares of Preferred Stock into which the unpaid principal balance of this Note
is convertible) as provided in this Note. The Preferred Stock issued upon
conversion of this Note shall

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have the same rights, preferences and limitations as the shares of Preferred
Stock issued to Holder on the date of this Note including, without limitation,
adjustments of the conversion price of the Preferred Stock into shares of common
stock, par value $.0001 per share, of the Company, that occur after the date of
this Note.

     (b) In order for Maker or Holder to convert the unpaid principal balance of
this Note into shares of Preferred Stock and subject to Section 3(a) above,
Maker or Holder must deliver a notice to Holder or Maker, respectively, at its
address of record stating that Maker or Holder elects to convert the unpaid
principal balance of this Note (or elected portion thereof with respect to a
conversion in part) into Preferred Stock. Promptly upon receipt of such notice
if sent by Maker, Holder shall surrender the Note to Maker, endorsed or
accompanied by a written instrument or instruments of transfer, in form
reasonably satisfactory to Maker, duly executed by Holder or its attorney duly
authorized in writing. If Holder shall deliver the notice of conversion, Holder
shall surrender to Maker this Note, endorsed or accompanied by a written
instrument or instruments of transfer, together with Holder's notice of
conversion. The date of mailing of the above-described notice shall be the
conversion date (the "Conversion Date") and the conversion shall be deemed
effective as of the close of business on the Conversion Date. No fractional
shares of Preferred Stock shall be issued upon conversion of the unpaid
principal balance of this Note. Maker shall, as soon as practicable, and no more
than five business days, after the receipt of the surrendered Note, (i) issue
and deliver to Holder a certificate for the number of shares of Preferred Stock
to which Holder shall be entitled, together with an amount of cash in lieu of
any fraction of a share (to which Holder would otherwise be entitled but for the
preceding sentence) which shall be equal to the product of such fraction
multiplied by the Conversion Price and (ii) in the event of a conversion in
part, execute a new Note in substantially the form hereof in an aggregate
principal amount equal to the balance of the unpaid principal balance of this
Note not so converted.

     (c) Maker shall at all times prior to the Maturity Date, reserve and keep
available out of its authorized but unissued stock, for the purpose of effecting
the conversion of this Note, such number of its duly authorized shares of
Preferred Stock as shall from time to time be sufficient to effect the
conversion of all this Note into Preferred Stock pursuant to this Section 3.
Maker covenants that all of the shares of Preferred Stock which may be issuable
upon conversion of this Note and all of the shares of Common Stock of Maker
issuable upon conversion of the Preferred Stock shall be duly authorized,
validly issued, and fully paid, non-assessable shares of Maker, free from all
taxes, liens and other charges with respect to the issue thereof.

     (d) Upon conversion of this Note, this Note shall no longer be deemed to be
outstanding and all rights of Holder with respect to this Note shall immediately
cease and terminate at the close of business on the Conversion Date with regard
to the portion of the principal amount being converted, including without
limitation the obligation to pay such portion of the principal amount (except
the right of Holder to receive shares of Preferred Stock and cash in lieu of any
fraction of a share in exchange therefore and, in the event of a conversion in
part, the right of Holder to receive a new Note in substantially the form hereof
in an aggregate principal amount equal to the balance of the unpaid principal
balance of this Note not so converted).

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     (e) In the event the outstanding shares of Preferred Stock shall be split,
subdivided, combined or consolidated, by reclassification or otherwise, into a
greater or lesser number of shares of Preferred Stock, or in the event that
Maker shall issue shares of Preferred Stock by way of stock dividend or other
distribution to Holders of Preferred Stock, the Conversion Price in effect
immediately prior to such split, subdivision, stock dividend, combination or
consolidation shall, concurrently with the effectiveness of such split,
subdivision, stock dividend, combination or consolidation, be increased or
decreased proportionately.

     (f) Upon the occurrence of each adjustment or readjustment of the
Conversion Price pursuant to Section 3(a) and 3(e) above, Maker at its expense
shall promptly compute such adjustment or readjustment in accordance with the
terms hereof and furnish to Holder a certificate setting forth such adjustment
or readjustment and showing in detail the facts upon which such adjustment or
readjustment is based. Maker shall, upon the written request at any time of
Holder, promptly furnish or cause to be furnished to Holder a similar
certificate setting forth (i) such adjustments and readjustments, (ii) the
Conversion Price then in effect, and (iii) the number of shares of Preferred
Stock and the amount, if any, of other property that then would be received upon
the conversion of this Note.

     (g) If at any time or from time to time there shall be a Change of Control
(as defined in Section 4(c) below), then, as a part of such Change of Control,
(i) Maker shall provide to Holder written notice of such Change of Control at
least twenty (20) calendar days prior to consummation of such Change of Control
and (ii) provision shall be made so that the successor corporation resulting
from such Change in Control assumes this Note and, by the written election of
Holder to Maker that Holder shall not deem such Change of Control an Event of
Default (as defined below), Holder shall thereafter be entitled to receive upon
conversion of this Note the number of shares of stock or other securities or
property of the successor corporation resulting from such Change in Control to
which a holder of Preferred Stock issuable upon conversion would have been
entitled on such Change of Control. In any such case, appropriate adjustment (as
determined in good faith by the Board of Directors of Maker) shall be made in
the application of the provisions of this Section 3 with respect to the rights
and interest thereafter of Holder after the Change of Control to the end that
the provisions of this Section 3 (including adjustment of the Conversion Price
then in effect and the number of shares acquirable upon conversion of this Note)
shall be applicable after the Change of Control in as nearly equivalent a manner
as may be practicable. This provision shall not limit the right of Maker or
Holder to convert this Note nor the right of Holder to accelerate this Note
under Sections 4(c) and 5 below, respectively. In the event this Note is
accelerated under Sections 4(c) and 5 below, all amounts due hereunder shall be
paid to Holder by Maker or its successor upon the Change of Control.

4.   Breach of Covenants and Bankruptcy

The occurrence of any of the following shall constitute an "Event of Default"
hereunder:

     (a) Failure to Pay. Maker shall fail to pay (i) any principal payment on
the due date hereunder or (ii) any other payment required pursuant to the terms
hereof on the date due; or

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     (b) Breaches of Covenants. Maker shall fail to observe or perform any
covenant, obligation, condition or agreement contained herein and such failure
shall continue for ten days after Maker's receipt of Holder's written notice to
Maker of such failure; or

     (c) Change of Control. A Change of Control shall have occurred with respect
to Maker. For purposes hereof, the term "Change of Control" means the occurrence
of one or more of the following events: (a) any sale, lease, exchange or other
transfer (in one transaction or a series of related transactions) of all or
substantially all of the assets of Maker and its subsidiaries, taken as a whole,
to any Person or group of related Persons, as defined in Section 13(d) of the
Securities Exchange Act of 1934 (a "Group"); and (b) any Person or Group
(excluding owners of equity securities as of the date of this Note) shall become
the owner, directly or indirectly, beneficially or of record, of shares
representing more than 50% of the aggregate ordinary voting power represented by
Maker's issued and outstanding voting stock or any successor to all or
substantially all of Maker's assets; or

     (d) Voluntary Bankruptcy or Insolvency Proceedings. Maker shall (i) apply
for or consent to the appointment of a receiver, trustee, liquidator or
custodian of itself or of all or a substantial part of its property; (ii) admit
in writing its inability, to pay its debts generally as they mature; (iii) make
a general assignment for the benefit of its or any of its creditors; (iv) be
dissolved or liquidated in full or in part; or (iv) commence a voluntary case or
other proceeding seeking liquidation, reorganization or other relief with
respect to itself or its debts pursuant to any bankruptcy, insolvency or other
similar law now or hereafter in effect or consent to any such relief or to the
appointment of or taking possession of its property by any official in an
involuntary case or other proceeding commenced against it; or

     (e) Involuntary Bankruptcy or Insolvency Proceedings. Proceedings for the
appointment of a receiver, trustee, liquidator or custodian of Maker or of all
or a substantial part of the property thereof, or an involuntary case or other
proceedings seeking liquidation, reorganization or other relief with respect to
Maker or the debts thereof pursuant to any bankruptcy, insolvency or other
similar law now or hereafter in effect shall be commenced and an order for
relief entered or such proceeding shall not be dismissed or discharged within
ninety days of commencement.

5.   Rights of Holder upon Default

Upon the occurrence or existence of any Event of Default, and at any time
thereafter during the continuance of such Event of Default, Holder may, by
written notice to Maker, declare all outstanding obligations payable by Maker
hereunder to be immediately due and payable without presentment, demand, protest
or any other notice of any kind, all of which are hereby expressly waived;
except that upon the occurrence or existence of any Event of Default set forth
in Sections 4(d) or (e) herein, all of the outstanding obligations payable by
Maker hereunder shall automatically become immediately due and payable without
presentment, demand, protest or any other notice of any kind, all of which are
hereby expressly waived. No delay or omission by Holder in exercising any right
shall operate as a waiver of such right or any other right under this Note; a
waiver on any one occasion shall not be construed as a bar to or waiver of any
right on any future occasion. In addition to the foregoing remedies, upon the
occurrence or existence of any Event of Default, Holder may exercise any other
right, power or remedy granted to it hereunder

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<PAGE>

or pursuant to applicable law. Maker agrees to pay all taxes levied or assessed
upon the outstanding principal against any holder of this Note. The prevailing
party in any action (i) to collect payment on this Note, (ii) in connection with
any dispute that arises as to its enforcement, validity, or interpretation,
whether or not legal action is instituted or prosecuted to judgment, or (iii) to
enforce any judgment obtained in any related legal proceeding, shall be entitled
to all costs and expenses incurred, including attorney fees. Furthermore, in the
event of any failure to pay an amount due under this Note when due, any such
overdue amount shall bear interest at a rate per annum which is equal to the
lesser of (a) two percent (2%) above the "Prime Rate" as listed in The Wall
Street Journal Money Rates report from time to time or (b) eight percent (8%),
from the date of such nonpayment until paid in full, payable upon demand.

6.   Governing Law

This Note shall be governed by the laws of the State of New York, excluding its
conflict of law rules.

7.   Amendments and Waivers

Any term of this Note may be amended or waived only with the written consent of
Maker and Holder. Any amendment or waiver effected in accordance with this
Section 7 shall be binding upon Maker, Holder and each transferee of the Note;
however, no such waiver shall affect or impair the rights of Holder to require
observance, performance, or satisfaction, either of that term or condition as it
applies on a subsequent occasion or of any other term or condition of this Note.
Notwithstanding the foregoing, Maker expressly agrees that this Note or any
payment under this Note may be extended by Holder in writing from time to time
without in any way affecting the liability of Maker.

8.   Transfer, Successors and Assigns

The terms and conditions of this Note shall inure to the benefit of and be
binding upon the respective successors and assigns of the parties. Neither this
Note nor any of the rights, interests or obligations hereunder may be assigned,
by operation of law or otherwise, in whole or in part, by Maker without the
prior written consent of Holder. This Note may not be sold or assigned by Holder
without prior written consent of Maker except in the event of a merger,
consolidation, or acquisition of Holder or any business unit thereof and Holder
may pledge this Note to any financial institution as collateral upon written
notice to Maker.

9.   Notices

Any notice required or permitted by this Note shall be in writing and shall be
deemed sufficient upon delivery, when delivered personally or by a
nationally-recognized delivery service (such as Federal Express or UPS), or five
days after being deposited in the U.S. mail, as certified or registered mail,
with postage prepaid, addressed to the party to be notified at such party's
address as set forth below or as subsequently modified by written notice;
provided that all notices under Section 3 shall only be sent by
nationally-recognized delivery service.

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10.  Severability

If any provision or any word, term, clause, or part of any provision of this
Note shall be invalid for any reason, the same shall be ineffective, but the
remainder of this Note and of the provision shall not be affected and shall
remain in full force and effect.

11.  Subordination

Maker's obligations under this Note shall be subordinate in right of payment to
Senior Indebtedness of Maker. This Note shall be subject to the forms of
subordination agreement requested from time to time by holders of Senior
Indebtedness (as defined below), and Holder agrees to enter into such forms of
subordination agreement upon request of such holders of Senior Indebtedness and
be bound by such agreements. "Senior Indebtedness" as used herein shall mean the
principal of (and premium, if any) and unpaid interest on, indebtedness of
Maker, or with respect to which Maker is a guarantor, outstanding or under
credit lines existing as of the date of this Note, or to banks, insurance
companies, lease financing institutions or other lending institutions or
business units of such institutions regularly and primarily engaged in the
business of lending money, which is for money borrowed (or purchase or lease of
equipment in the case of lease financing) by Maker, and which is approved by the
Board of Directors of Maker, whether or not secured, and whether or not
previously incurred or incurred in the future, or indebtedness of Maker to
sellers of land, equipment, furniture, fixtures, components or assets or stock
secured by the asset or shares purchased. Other than Senior Indebtedness, the
indebtedness owing under this Note shall not rank junior in right of priority of
payment to borrowed money of Maker incurred hereafter.

IN WITNESS WHEREOF, Maker has caused this Convertible Promissory Note to be
issued as of the date first written above.

MAKER: IPG PHOTONICS CORPORATION

By: /s/ Valentin P. Gapontsev
    ---------------------------------
Name: Valentin P. Gapontsev
Title: CEO and Chairman
Address: 50 Old Webster Road
         Oxford, MA 01540
Attn: General Counsel

AGREED TO AND ACCEPTED:
HOLDER: JDS UNIPHASE CORPORATION

By: /s/ Christopher S. Dewees
    ---------------------------------
Name: Christopher S. Dewees
Title: Vice President
Address: 1768 Automation Parkway
         San Jose, California 95131
Attn: General Counsel

                                       6<PAGE>

                                                                   EXHIBIT 10.34

                             SECURED PROMISSORY NOTE

$6,079,472.60                                                    August 13, 2003
Oxford, Massachusetts

FOR VALUE RECEIVED, IPG PHOTONICS CORPORATION, a Delaware corporation ("Maker"),
promises to pay to JDS UNIPHASE CORPORATION, a Delaware corporation ("Holder"),
the principal sum of SIX MILLION, AND SEVENTY-NINE THOUSAND, FOUR HUNDRED AND
SEVENTY TWO and 60/100 DOLLARS ($6,079,472.60); with interest from the date of
this Note on the unpaid principal amounts owing from time to time as provided
below. This Note is subject to the following terms and conditions:

1.   Maturity

(a) Principal plus all accrued but unpaid interest on the principal amount
outstanding shall be due and payable in the following amounts and on the
following dates:

<TABLE>
<CAPTION>
Principal Amount                              Date Due
----------------                              --------
<S>                                           <C>
$333,000                                      September 30, 2003
$334,000                                      December 31, 2003
$500,000                                      March 31, 2004
$500,000                                      June 30, 2004
$500,000                                      September 30, 2004
$500,000                                      December 31, 2004
One-quarter of then unpaid principal amount   March 31, 2005
One-quarter of then unpaid principal amount   June 30, 2005
One-quarter of then unpaid principal amount   September 30, 2005
Remaining of unpaid principal amount          December 31, 2005 (the "Maturity Date")
</TABLE>

(b) Maker shall make the following mandatory prepayments to Holder against the
unpaid interest and principal sum, in that order, on this Note within five
business days of Maker's receipt of the cash funds: (i) 50% of all cash
collateral released to Maker by BankNorth, NA or its successor ("BankNorth"), in
calendar years 2003 and/or 2004, which cash collateral, as of the date of the
Note is being held by BankNorth under that certain Construction Loan Agreement,
dated April 28, 2000 between Maker and BankNorth, as amended from time to time
("Construction Loan Agreement"); (ii) 75% of all cash collateral released to
Maker by BankNorth in calendar year 2005, which cash collateral, as of the date
of the Note is being held by BankNorth under the Construction Loan Agreement;
(iii) 10% of the net cash proceeds received by Maker from the issuance of any
securities (including without limitation any securities convertible or
exchangeable into Common Stock), options, warrants, call rights or debt
instruments after the date of this Note, excluding exercises of stock options by
employees, directors, advisors and consultants in the ordinary course; and (iv)
100% of the net cash proceeds received by Maker from any sale of the equipment,
furniture, fixtures, inventory or land pledged to Holder under the Security
Agreement or the Mortgage (each as hereinafter defined); but in no case shall
Maker be required to pay an amount under this Section 1(b) in excess of the
unpaid interest and principal amount of this Note.

<PAGE>

(c) On or before the 15th day of April, July, October and January of each year
for so long as there is any unpaid principal amount under this Note, any one of
the Chief Executive Officer, President, or Chief Financial Officer shall send a
written statement to Holder setting forth whether or not any of the events in
Section 1(b) has occurred in the last calendar quarter, giving short description
of any of the events that has occurred in the last calendar quarter and whether
Maker has complied with its prepayment obligations hereunder.

(d) Holder shall apply all mandatory principal prepayments received by Holder
under clause (b) to the payment of accrued and unpaid interest, and then against
required payments in the reverse order of maturity (i.e., applied to latest
payments under Section 1(a) first).

(e) All optional principal prepayments upon this Note shall be applied to the
payment of accrued and unpaid interest, and then against required payments in
the order of maturity (i.e., applied to earliest payments under Section 1(a)
first), it being agreed that an optional repayment of principal shall relieve
the obligation of Maker to make payment of the portion of the principal amount
against which the optional prepayment was applied.

2.   Interest

The outstanding principal owing from time to time hereunder will bear interest
at the rate of FOUR PERCENT per annum (compounded annually) until fully paid.
Accrued but unpaid interest shall be payable at such time as the outstanding
principal amount hereof is otherwise due and payable, commencing September 30,
2003. Computations of interest shall be based on a year of 360 days but shall be
calculated for the actual number of days in the period for which interest is
charged.

3.   Payments

Maker shall make payments in lawful money of the United States of America and in
immediately available funds. All payments under this Note shall be made to
Holder at JDS Uniphase Corporation, 1768 Automation Parkway, San Jose,
California 95131, ATTN: General Counsel, or at such other address as Holder
shall direct Maker in writing. This Note may be prepaid in whole or in part,
without penalty, at the option of Maker and without the consent of Holder.

4.   Breach of Covenants and Bankruptcy

The occurrence of any of the following shall constitute an "Event of Default"
hereunder:

(a)  Failure to Pay. Maker shall fail to pay (i) any principal payment on the
     due date hereunder or (ii) any interest or other payment required pursuant
     to the terms hereof on the date due and such payment shall not have been
     made within thirty days of Maker's receipt of Holder's written notice to
     the Maker of such failure to pay; or

(b)  Breaches of Covenants. Maker shall fail to observe or perform any covenant,
     obligation, condition or agreement contained herein, or in the Security
     Agreement or the Mortgage and (i) such failure shall continue for thirty
     days after Maker's receipt of Holder's written notice to the Maker of such
     failure, or (ii) if such failure is not curable within such thirty-day
     period, but is reasonably capable of cure within forty-five days, either
     (A) such failure shall continue for forty-five days or (B) Maker shall not
     have commenced and continued

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     to prosecute a cure in a manner reasonably satisfactory to Holder within
     and continuously during the initial thirty-day period; or

(c)  Change of Control. A Change of Control shall have occurred with respect to
     Maker. For purposes hereof, the term "Change of Control" means the
     occurrence of one or more of the following events: (a) any sale, lease,
     exchange or other transfer (in one transaction or a series of related
     transactions) of all or substantially all of the assets of IPG and its
     subsidiaries, taken as a whole, to any Person or group of related Persons,
     as defined in Section 13(d) of the Securities Exchange Act of 1934 (a
     "Group"); and (b) any Person or Group (excluding owners of equity
     securities as of the date of this Note) shall become the owner, directly or
     indirectly, beneficially or of record, of shares representing more than 50%
     of the aggregate ordinary voting power represented by IPG's issued and
     outstanding voting stock or any successor to all or substantially all of
     the Company's assets.

(d)  Voluntary Bankruptcy or Insolvency Proceedings. Maker shall (i) apply for
     or consent to the appointment of a receiver, trustee, liquidator or
     custodian of itself or of all or a substantial part of its property; (ii)
     admit in writing its inability, to pay its debts generally as they mature;
     (iii) make a general assignment for the benefit of its or any of its
     creditors; (iv) be dissolved or liquidated in full or in part; or (iv)
     commence a voluntary case or other proceeding seeking liquidation,
     reorganization or other relief with respect to itself or its debts pursuant
     to any bankruptcy, insolvency or other similar law now or hereafter in
     effect or consent to any such relief or to the appointment of or taking
     possession of its property by any official in an involuntary case or other
     proceeding commenced against it; or

(e)  Involuntary Bankruptcy or Insolvency Proceedings. Proceedings for the
     appointment of a receiver, trustee, liquidator or custodian of the Maker or
     of all or a substantial part of the property thereof, or an involuntary
     case or other proceedings seeking liquidation, reorganization or other
     relief with respect to the Maker or the debts thereof pursuant to any
     bankruptcy, insolvency or other similar law now or hereafter in effect
     shall be commenced and an order for relief entered or such proceeding shall
     not be dismissed or discharged within ninety days of commencement.

5.   Rights of Holder upon Default

Upon the occurrence or existence of any Event of Default, and at any time
thereafter during the continuance of such Event of Default, Holder may, by
written notice to the Maker, declare all outstanding obligations payable by the
Maker hereunder to be immediately due and payable without presentment, demand,
protest or any other notice of any kind, all of which are hereby expressly
waived; except that upon the occurrence or existence of any Event of Default set
forth in Sections 4(c), (d) or (e) herein, all of the outstanding obligations
payable by the Maker hereunder shall automatically become immediately due and
payable without presentment, demand, protest or any other notice of any kind,
all of which are hereby expressly waived. No delay or omission by Holder in
exercising any right shall operate as a waiver of such right or any other right
under this Note; a waiver on any one occasion shall not be construed as a bar to
or waiver of any right on any future occasion. In addition to the foregoing
remedies, upon the occurrence or existence of any Event of Default, Holder may
exercise any other right, power or remedy granted to it hereunder or pursuant to
applicable law. The Maker agrees to pay all taxes levied or assessed upon the
outstanding

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<PAGE>

principal against any holder of this Note. The prevailing party in any action
(i) to collect payment on this Note, (ii) in connection with any dispute that
arises as to its enforcement, validity, or interpretation, whether or not legal
action is instituted or prosecuted to judgment, or (iii) to enforce any judgment
obtained in any related legal proceeding, shall be entitled to all costs and
expenses incurred, including attorney fees.

6.   Governing Law

This Note shall be governed by the laws of the State of New York, excluding its
conflict of law rules.

7.   Amendments and Waivers

Any term of this Note may be amended or waived only with the written consent of
the Maker and the Holder. Any amendment or waiver effected in accordance with
this Section 7 shall be binding upon the Maker, the Holder and each transferee
of the Note; however, no such waiver shall affect or impair the rights of Holder
to require observance, performance, or satisfaction, either of that term or
condition as it applies on a subsequent occasion or of any other term or
condition of this Note. Notwithstanding the foregoing, Maker expressly agrees
that this Note or any payment under this Note may be extended by Holder in
writing from time to time without in any way affecting the liability of Maker.

8.   Transfer, Successors and Assigns

The terms and conditions of this Note shall inure to the benefit of and be
binding upon the respective successors and assigns of the parties. Neither this
Note nor any of the rights, interests or obligations hereunder may be assigned,
by operation of law or otherwise, in whole or in part, by the Maker without the
prior written consent of Holder.. This Note may not be sold or assigned by
Holder without prior written consent of Maker except in the event of a merger,
consolidation, or acquisition of Holder or any business unit thereof and Holder
may pledge this Note to any financial institution as collateral upon written
notice to Maker.

9.   Notices

Any notice required or permitted by this Note shall be in writing and shall be
deemed sufficient upon delivery, when delivered personally or by a
nationally-recognized delivery service (such as Federal Express or UPS), or five
days after being deposited in the U.S. mail, as certified or registered mail,
with postage prepaid, addressed to the party to be notified at such party's
address as set forth below or as subsequently modified by written notice.

10.  Severability

If any provision or any word, term, clause, or part of any provision of this
Note shall be invalid for any reason, the same shall be ineffective, but the
remainder of this Note and of the provision shall not be affected and shall
remain in full force and effect.

11.  Holder's Security Interest and Mortgage

THIS NOTE IS SECURED BY A SECURITY INTEREST IN CERTAIN ASSETS OF MAKER MORE
FULLY DESCRIBED IN (I) THE SECURITY AGREEMENT DATED THE SAME DATE AS THIS NOTE
BETWEEN MAKER, AS DEBTOR, AND HOLDER, AS SECURED PARTY ("SECURITY

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<PAGE>

AGREEMENT") AND (II) THE MORTGAGE DATED THE SAME DATE AS THIS NOTE MADE BY
MAKER, AS DEBTOR, AS MORTGAGOR, AND HOLDER, AS MORTGAGEE ("MORTGAGE").

IN WITNESS WHEREOF, the Maker has caused this Secured Promissory Note to be
issued as of the date first written above.

MAKER: IPG PHOTONICS CORPORATION

By: /s/ Valentin P. Gapontsev
    ---------------------------------
Name: Valentin P. Gapontsev
Title: CEO and Chairman
Address: 50 Old Webster Road
Oxford, MA 01540
Attn: General Counsel

AGREED TO AND ACCEPTED:

HOLDER: JDS UNIPHASE CORPORATION

By: /s/ Christopher S. Dewees
    ---------------------------------
Name: Christopher S. Dewees
Title: Vice President
Address: 1768 Automation Parkway
San Jose, California 95131
Attn: General Counsel

                                       5

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