<PAGE>

         THE SECURITIES REPRESENTED BY THIS CERTIFICATE 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 IN A FORM SATISFACTORY TO THE COMPANY
THAT SUCH REGISTRATION IS NOT REQUIRED UNDER THE SECURITIES ACT OF 1933.


                             SECURED PROMISSORY NOTE
                             -----------------------


$60,000.00                                                         April 2, 2003
                                                             Clearwater, Florida

         For value received, Digital Lightwave, Inc., a Delaware corporation
(the "Company"), promises to pay to Optel, LLC (the "Holder"), the principal sum
of Sixty Thousand Dollars ($60,000.00). Interest shall accrue from the date of
this Note on the unpaid principal amount at a rate equal to 10.0% per annum,
compounded annually. This Note is subject to the following terms and conditions.

         1. MATURITY. Principal and any accrued but unpaid interest under this
Note shall be due and payable upon demand by the Holder at any time after July
31, 2004 (the "Maturity Date"). Notwithstanding the foregoing, the entire unpaid
principal sum of this Note, together with accrued and unpaid interest thereon,
shall become immediately due and payable immediately prior to the earlier to
occur of (a) a Change of Control (as defined below), (b) the insolvency of the
Company, (c) the commission of any act of bankruptcy by the Company, (d) the
execution by the Company of a general assignment for the benefit of creditors,
(e) the filing by or against the Company of a petition in bankruptcy or any
petition for relief under the federal bankruptcy act or the continuation of such
petition without dismissal for a period of 90 days or more, or (f) the
appointment of a receiver or trustee to take possession of the property or
assets of the Company. For purposes of this Note a "Change of Control" shall
mean a sale of all or substantially all of the Company's assets, or any merger
or consolidation of the Company with or into another corporation; other than a
merger or consolidation in which the holders of more than 50% of the shares of
capital stock of the Company outstanding immediately prior to such transaction
continue to hold (either by the voting securities remaining outstanding or by
their being converted into voting securities of the surviving entity) more than
50% of the total voting power represented by the voting securities of the
Company, or such surviving entity, outstanding immediately after such
transaction.

         2. PAYMENT; PREPAYMENT. All payments shall be made in lawful money of
the United States of America at such place as the Holder hereof may from time to
time designate in writing to the Company. Payment shall be credited first to the
accrued interest then due and payable and the remainder applied to principal.
Prepayment of this Note may be made at any time without penalty.

<PAGE>


         3. 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. This Note may be transferred only upon surrender of
the original Note for registration of transfer, duly endorsed, or accompanied by
a duly executed written instrument of transfer in form satisfactory to the
Company. Thereupon, a new note for the same principal amount and interest will
be issued to, and registered in the name of, the transferee. Interest and
principal are payable only to the registered holder of this Note.

         4. GOVERNING LAW. This Note and all acts and transactions pursuant
hereto and the rights and obligations of the parties hereto shall be governed,
construed and interpreted in accordance with the laws of the State of Florida,
without giving effect to principles of conflicts of law.

         5. NOTICES. Any notice required or permitted by this Agreement shall be
in writing and shall be deemed sufficient upon receipt, when delivered
personally or by courier, overnight delivery service or confirmed facsimile, or
48 hours after being deposited in the U.S. mail as certified or registered mail
with postage prepaid, if such notice is addressed to the party to be notified at
such party's address or facsimile number as set forth below or as subsequently
modified by written notice.

         6. AMENDMENTS AND WAIVERS. Any term of this Note may be amended only
with the written consent of the Company and the Holder. Any amendment or waiver
effected in accordance with this Section 6 shall be binding upon the Company,
each Holder and each transferee of any Note.

         8. OFFICERS AND DIRECTORS NOT LIABLE. In no event shall any, officer or
director of the Company be liable for any amounts due or payable pursuant to
this Note.

         9. SECURITY INTEREST. This Note is secured by all of the assets of the
Company in accordance with a separate security agreement originally dated as of
February 14, 2003 and amended and restated as of the date hereof (the "Security
Agreement"), between the Company and the Holder. In case of an Event of Default
(as defined in the Security Agreement), the Holder shall have the rights set
forth in the Security Agreement.

         10. COUNTERPARTS. This Note may be executed in any number of
counterparts, each of which will be deemed to be an original and all of which
together will constitute a single agreement.

         11. ACTION TO COLLECT ON NOTE. If action is instituted to collect on
this Note, the Company promises to pay all costs and expenses, including
reasonable attorney's fees, incurred in connection with such action.

         12. LOSS OF NOTE. Upon receipt by the Company of evidence satisfactory
to it of the loss, theft, destruction or mutilation of this Note or any Note
exchanged for it, and indemnity satisfactory to the Company (in case of loss,
theft or destruction) or surrender and cancellation of such Note (in the case of
mutilation), the Company will make and deliver in lieu of such Note a new Note
of like tenor.


                                      -2-
<PAGE>



         This Note was entered into as of the date set forth above.


                                    COMPANY:

                                    DIGITAL LIGHTWAVE, INC.


                                    By:_________________________________________

                                    Name:_______________________________________
                                                        (print)
                                    Title:______________________________________




AGREED TO AND ACCEPTED:

OPTEL, LLC


By:  _________________________

Name: ________________________
               (print)
Title:  ______________________









                                      -3-