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                                                                   Exhibit 10.20


                            (DIGITAL LIGHTWAVE LETTERHEAD)


                                                     601 Cleveland Street
                                                     Fifth Floor
                                                     Clearwater, Florida 33755

Mr. George J. Matz                                   Telephone: 813.442.6677
One Gussett Road                                     Facsimile: 813.442.5680
Wenham, MA 01984                                     Email: info@lightwave.com
                                                     URL:http:/www.lightwave.com
                                                      
                                                     CONFIDENTIAL
                                                     PAGE 1 OF 3

                                                     April 13, 1998


                              RE: Employment Terms

Dear George,

The following letter constitutes the terms of employment associated with the
position of Executive Vice President, Global Marketing and Sales of Digital
Lightwave, Inc. (the "Company"). The terms of this letter are subject to
paragraphs 12 and 13 hereof.

1.   Capacity And Responsibilities. As the Executive Vice President, Global
     Marketing and Sales, you will be responsible for creating, implementing
     and directing the sales and marketing strategy, policy, and operations of
     the Company, as approved by the Chief Executive. You will be fully
     responsible for the development and management of the sales and marketing
     of the Company's products including the Company's Network Information
     Computer (NIC), its Remote Access Agent (RAA), its international products
     including its SDH NIC, and of its products currently in development
     including its OC-48 product and its Optical Access Agent product and
     others. The quarterly sales targets for 1998 are $5.3, $7.5, $10.0 and
     $12.2 respectively.

     You will be responsible for the day-to-day execution of the sales and
     marketing organizations, the articulation of its targets and goals, and of
     its effective plans in alignment with the goals and objectives of the
     Company, as approved by the Chief Executive Officer. The Company expects
     that you will closely coordinate your efforts with the Company's
     employees, executives, and senior executives. You will also provide
     support and resources regarding financial matters relating to sales and
     marketing to the other executives of the Company. The executives reporting
     to you will be the Vice Presidents of Marketing, North American Sales,
     International Sales, and Customer Service and Support. All positions are
     currently filled except for the Vice President, Marketing.

     In addition to the foregoing, you will manage the building and staffing of
     the Marketing Division. Your duties in this area will include, but not be
     limited to, managing the Vice President, Marketing articulating the plans
     and implementing the accomplishments of developing or providing, market
     research, market definition and sizing, competitive product and feature
     analysis, new feature proposals, extensive and detailed product
     requirements, representation at industry conferences and trade shows,
     customer contract and liaison, as well as providing content and approach
     for the planning and execution of advertising and promotional campaigns for
     the Company's products by the marketing communications group.




                                                      GJM
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                                                    Initials
<PAGE>   2

Page 2 of 3

George J. Matz
April 13, 1998

     It is expected that the net impact of your sales and marketing management
     and efforts will be to significantly increase the Company's awareness of
     the market and competitive environment of the Company's products and to
     result in greater market acceptance and increased demand for the Company's
     products, which then results in increased sales, and then through effective
     sales management, increased revenue, and profit for the Company. You will
     report directly to the Chief Executive Officer. The Company manages by
     statistics, therefore, you will be responsible for your statistical
     performance and that of any subordinates you manage. You will manage your
     subordinates in accordance with the policies and procedures of the Company
     now or hereafter existing.

2.   Exclusive Services. During your term of employment it is expected that you
     will be a full time employee of the Company. It will be required that your
     services be exclusive to the Company and that you will devote your
     productive time and attention to the performance of your duties during the
     term of employment. It is expected that when not travelling on Company
     business you will spend the majority of your time at Company headquarters
     in Florida.

3.   Confidentiality and Intellectual Property Rights. During the term of your
     employment, you will occupy a position of trust and confidence and
     therefore will be required to maintain the confidentiality of Company
     information. You will be required, as are all employees, to sign an
     Assignment of Intellectual Property Rights Agreement, wherein the employee
     acknowledges and agrees that all intellectual property, inventions and
     trade secrets are and shall be the sole property of the Company. The
     Confidentiality Agreement extends beyond cessation of employment.

4.   Compensation. The Company is offering you a base salary of $225,000 per
     year with a twenty percent (20%) bonus guaranteed for the first year only,
     at the conclusion of your first year of employment. The Company is also
     planning an executive bonus plan of which you will participate. If under
     that participation, your first year bonus is higher than 20% of your base
     compensation the higher bonus will take precedent. Also, under its 401(k)
     plan of which you may participate, the Company provides a 50% matching
     contribution to employee contributions up to 6% of salary, which vests
     after one year of employment. Employees of the Company are also eligible
     to purchase shares of Company stock on an attractive basis under its Stock
     Purchase Plan.

5.   Sign-on Bonus. You will receive a $150,000 sign-on bonus which is payable
     in increments of $50,000, at the beginning of each of your first three (3)
     years of employment.

6.   Automobile Allowance. You will be given an automobile leasing and expense
     arrangement that is acceptable to you and does not $1,000 per month.

7.   Expense Reimbursement. Hotel, car rentals, meals, etc. will be paid by you
     at the time of purchase; you will then be reimbursed 100% by the Company.
     All expenses charged to the Company are subject to review by the
     Controller and may require justification.

8.   Benefits. You will be entitled to participate in the insurance and benefit
     programs of the Company and will also be entitled to receive the normal
     vacation/holiday allocation. The Company offers a comprehensive insurance
     package, which includes medical, dental, disability and life insurance.
     All employees receive 10 paid vacation days, 12 paid holidays, and 5 paid
     sick days (paid only in the event of illness) per year. Please note that
     should you wish to utilize the Company's insurance benefits, the insurance
     carrier enrolls people only on the first business day of each calendar
     month, therefore, the Company will enroll you on the first such day after
     your start of employment.


                                                            GJM
                                                            ---
                                                          Initials


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Page 3 of 3

George J. Matz
April 13, 1998

9.   Stock Options. The Company will recommend to the Compensation Committee
     the issuance to you of 300,000 shares of Common Stock of the Company,
     75,000 shares will vest after six (6) months of employment and an
     additional 75,000 shares will vest on your employment anniversary date
     over the next three (3) years. The exercise price of the optioned shares
     will be the closing market price of the Company's Common Stock on the date
     immediately prior to the date of award by the Compensation Committee. In
     the event that a change of control occurs, you will automatically be
     vested in all of your outstanding stock options. A change of control shall
     mean the merger or consolidation of the Company in which the Company is
     the acquired part, or the sale of all, or substantially all of the assets
     of the Company or if Bryan J. Zwan and/or his family cease to have voting
     control of the common stock of the Company.

10.  Pay Periods. The Company pays base salary twice a month, on the 15th and
     the final day of each month.

11.  At-will Employment.  This letter is not an employment contract. During the
     entire course of your employment with the Company you will be an at-will
     employee. This means that you will be free to terminate your employment
     with the Company at any time, with or without reason, and the Company will
     have the right to terminate your employment or the employment of others at
     any time, with or without reason. This employment relationship may only be
     altered by written agreement signed by the Chief Executive Officer of the
     Company.

12.  Start of Employment. The Company would like to commence your employment on
     or before May 6, 1998.

13.  Duration of Offer. This offer is valid until the close of business April
     15, 1998.

14.  Due Diligence. Subsequent to the date hereof the Company intends to
     continue its due diligence process. In the event that the Company
     discovers that any act has occurred which could, with the passage of time
     and taking of action, constitute "cause" under the Severance Payment
     Agreement, the terms of employment set forth herein may be voided by the
     Company.

Best Regards,
Digital Lightwave, Inc.


/s/ Steven H. Grant
-------------------------------------
    Steven H. Grant
    Chief Financial Officer



                                         Acknowledgement of receipt and
                                         acceptance of the foregoing:


                                         /s/ George J. Matz     April 30, 1998
                                         -------------------------------------
                                             George J. Matz           Date

<PAGE>   4
February 9, 1999


Mr. George J. Matz
One Gussett Road
Wenham, MA  01984
                                                                 CONFIDENTIAL
                                                                 Page 1 of 3

     Re: Employment Terms/Addendum to Employment Letter dated April 13, 1998.

Dear George,

This employment letter serves as an addendum to your original employment
letter, dated April 13, 1998 and, as we agreed, effective February 9, 1999, you
will assume the new position of Executive Vice President, General Manager of
Network Products.

1.       Capacity And Responsibilities  As the Executive Vice President, General
         Manager of Network Products you will be responsible for all sales of
         the Network Access Product family. You will report directly to the
         President and Chief Executive Officer of the Company. You will be
         responsible for the development and management of all sales and
         marketing programs for Network Products division. Your assigned 1999
         sales quota for this product family is $15M. The details of your 1999
         compensation incentives associated with the achievement of your
         assigned targets will be outlined in your 1999 Incentive Compensation
         Plan.

         In this capacity, you will be responsible for the effective planning
         and achievement of targets and goals of the Network Access Products
         family, in alignment with the goals and objectives of the Company, as
         approved by the President and Chief Executive Officer. The Company
         expects that you will closely coordinate your efforts with the
         Company's employees, executives, and senior executives. You will also
         provide support and resources regarding financial matters relating to
         sales of Network Access Products, to other executives of the Company.

2.       Exclusive Services  During the term of your employment, it is expected
         that you will be a full time employee of the Company. As the executive
         responsible for the Network Products Sales, you will continue to
         reside in the Boston area. You are expected at Digital Lightwave
         Headquarters in Clearwater, Florida, no less than twice monthly for
         major account reviews. You will spend a significant amount of time
         traveling to the Company's New Jersey facility and other areas of
         identified opportunities.

3.       Confidentiality and Intellectual Property Rights  No change to the
         employment terms stated in the letter dated April 13, 1998.

4.       Compensation  Your base salary remains the same as stated in the letter
         dated April 13, 1998. A first year 20% bonus guarantee will be paid
         upon your one year anniversary with the Company. The full amount of
         this bonus will be recoverable by the Company should you choose to
         terminate your employment prior to December 31, 1999. If the Company
         terminates your employment before December 31, 1999, this bonus will
         not be recoverable.


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                                                                     -----
                                                                     Initials

George J. Matz
February 9, 1999
Page 2 of 3



5.       Sign on Bonus  Your two remaining sign on bonuses of $50,000 each will
         be paid to you on January 15, 2000 and July 15, 2000 respectively. If
         the Company elects to terminate your employment on or before December
         31, 1999, the $50,000 sign on bonus originally earned on your first
         anniversary (in accordance with your employment letter dated April 13,
         1998), will be due and payable upon termination. In the event the
         Company terminates your employment on or before December 31, 1999, no
         other sign on bonus, either whole or pro-rated, will be payable to
         you.

         In the event that you choose to terminate your employment with the
         Company prior to December 31, 1999, no sign on bonuses will be paid.

6.       Automobile Allowance  No change to the employment terms stated in the
         letter dated April 13, 1998.

7.       Expense Reimbursement  All expenses charged to the Company are subject
         to the review of the President, Chief Executive Office and the
         Controller.

8.       Benefits  No change to the employment terms stated in the letter dated 
         April 13, 1998.

9.       Stock Options  All stock option terms stated in your original
         employment letter dated April 13, 1998 remain in force with the
         following exception: The stock options that were scheduled to vest on
         May 30, 1999 are now scheduled to vest on December 31, 1999. All other
         stock option vesting schedules will remain as stated. In the event the
         Company terminates your employment prior to December 31, 1999, your
         stock option vesting schedules will revert to the original schedules
         outlined in your April 13, 1998 employment letter.

         In the event that you terminate your employment with the Company prior
         to December 31, 1999, the vesting schedule according to this letter
         will be enforced.

10.      Pay Periods  No change to the employment terms stated in the letter 
         dated April 13, 1998.

11.      At-will Employment  No change to the employment terms stated in the 
         letter dated April 13, 1998.

12.      Start of Employment  Your approved, unpaid personal leave of absence,
         commencing on February 1, 1999 and ending on February 8, 1999 will not
         result in an adjustment to your original hire date. Your original hire
         date will remain May 5, 1998 and your new responsibilities will
         commence on February 9, 1999.

13.      Duration of Offer  Not applicable.


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                                                                    Initials
George J. Matz
February 9, 1999
Page 3 of 3



14.      Due Diligence  No change to the employment terms stated in the letter 
         dated April 13, 1998.



Best Regards,
Digital Lightwave, Inc.



Gerry Chastelet
President and Chief Executive Officer Acknowledgement of receipt 
And acceptance of the foregoing:



                                                -------------------  ---------
                                                 George J. Matz         Date