<PAGE>   1


   As filed with the Securities and Exchange Commission on September ___, 1999
                         Registration No. 333-__________

================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                             ----------------------

                                    FORM S-8
                             REGISTRATION STATEMENT
                        UNDER THE SECURITIES ACT OF 1933

                             ----------------------

                                  HARMONIC INC.
             (Exact name of registrant as specified in its charter)
                      (formerly Harmonic Lightwaves, Inc.)

                DELAWARE                               77-0201147
      (State or other jurisdiction                    (IRS Employer
            of incorporation)                      Identification No.)

                                 549 Baltic Way
                           Sunnyvale, California 94089
                    (Address of principal executive offices)

                             ----------------------

                                 1995 Stock Plan
                       1999 Nonstatutory Stock Option Plan
                            (Full Title of the Plans)

                             ----------------------

                                 ANTHONY J. LEY
    CHAIRMAN OF THE BOARD OF DIRECTORS, PRESIDENT AND CHIEF EXECUTIVE OFFICER
                                  HARMONIC INC.
                                 549 BALTIC WAY
                           SUNNYVALE, CALIFORNIA 94089
                                 (408) 542-2500
           (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)

                                   Copies to:
                             JEFFREY D. SAPER, ESQ.
                        WILSON SONSINI GOODRICH & ROSATI
                            Professional Corporation
                               650 Page Mill Road
                           Palo Alto, California 94304



<PAGE>   2

<TABLE>
<CAPTION>
========================================================================================================
                                                        Proposed
                                                         Maximum
                Title of                   Amount       Offering            Proposed          Amount of
              Securities to                to be        Price Per       Maximum Aggregate   Registration
              be Registered              Registered     Share(1)          Offering Price        Fee(2)
--------------------------------------------------------------------------------------------------------
<S>                                       <C>           <C>              <C>                 <C>
Common Stock (par value $0.001 par        580,000       $105.9375        $61,443,750.00      $17,081.36
value) reserved for issuance under
the 1995 Stock Plan

Common Stock (par value $0.001 par        200,000       $105.9375        $21,187,500.00      $ 5,890.13
value) reserved for issuance under
the 1999 Nonstatutory Stock Option Plan
========================================================================================================
</TABLE>

(1)     Estimated pursuant to Rule 457(h) of the Securities Act of 1933, as
        amended, solely for the purpose of calculating the registration fee. The
        proposed maximum offering price per share with respect to each of the
        580,000 shares reserved for issuance under the 1995 Stock Plan and the
        200,000 shares reserved for issuance under the 1999 Nonstatutory Stock
        Option Plan was determined by reference to the fair market value of the
        Common Stock (the "FMV"), or, the average of the high and low price
        reported in the Nasdaq National Market on August 30, 1999.

(2)     Amount of Registration Fee was calculated pursuant to Section 6(b) of
        the Securities Act of 1933, which states that the fee shall be "$278 per
        $1 million" of the maximum aggregate price at which such securities are
        proposed to be offered. The Registration Fee is therefore calculated by
        multiplying the aggregate offering or sales amount by 0.000278.



<PAGE>   3

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3. INFORMATION INCORPORATED BY REFERENCE.

        There are hereby incorporated by reference in this Registration
Statement the following documents and information heretofore filed with the
Securities and Exchange Commission:

        (a)     The Registrant?s Annual Report on Form 10-K for the year ended
December 31, 1998 filed pursuant to Section 13(a) or 15(d) of the Securities
Exchange Act, as amended (the ?Exchange Act?).

        (b)     The Registrant?s quarterly reports on Form 10-Q for the quarter
ended April 2, 1999 and the quarter ended July 2, 1999 filed pursuant to Section
13(a) or 15(d) of the Exchange Act.

        (c)     The description of the Registrant's Common Stock contained in
the Registrant's Registration Statement on Form 8-A dated April 6, 1995, filed
pursuant to Section 12 of the Securities Exchange Act of 1934, as amended,
including any amendment or report filed for the purpose of updating such
description.

        All documents filed by the Registrant pursuant to Sections 13(a), 13(c),
14 and 15(d) of the Exchange Act after the date of this registration statement
and prior to the filing of a post-effective amendment which indicates that all
securities offered have been sold or which deregisters all securities then
remaining unsold, shall be deemed to be incorporated by reference in this
registration statement and to be part hereof from the date of filing such
documents.

ITEM 4. DESCRIPTION OF SECURITIES.

        Not applicable.

ITEM 5. INTERESTS OF NAMED EXPERTS AND COUNSEL.

        Not applicable.

ITEM 6. INDEMNIFICATION OF DIRECTORS AND OFFICERS.

        Section 145 of the Delaware General Corporations Law authorizes a court
to award, or a corporation's Board of Directors to grant, indemnification to
directors and officers in terms sufficiently broad to permit such
indemnification under certain circumstances for liabilities (including
reimbursement for expenses incurred) arising under the Securities Act. Article
VI of the Company's Bylaws provides for the mandatory indemnification of its
directors, officers, employees and other agents to the maximum extent permitted
by Delaware General Corporation Law, and the Company



<PAGE>   4

has entered into agreements with its officers, directors and certain key
employees implementing such indemnification.

ITEM 7. EXEMPTION FROM REGISTRATION CLAIMED.

        Not applicable.

ITEM 8. EXHIBITS.

<TABLE>
<CAPTION>
              Exhibit
              Number
              ------
<S>                     <C>
                5.1     Opinion of Wilson Sonsini Goodrich & Rosati,
                        Professional Corporation, as to the legality of
                        securities being registered.

                10.1    1995 Stock Plan, as amended.

                10.2    1999 Nonstatutory Stock Option Plan.

                23.1    Consent of Independent Accountants.

                23.2    Consent of Counsel (included in Exhibit 5.1).

                24.1    Power of Attorney (see page II-4).
</TABLE>

ITEM 9. UNDERTAKINGS.

        (a)     The undersigned Registrant hereby undertakes:

                (1)     To file, during any period in which offers or sales are
being made, a post-effective amendment to this registration statement to include
any material information with respect to the plan of distribution not previously
disclosed in the registration statement or any material change to such
information in the registration statement.

                (2)     That, for the purpose of determining any liability under
the Securities Act, each such post-effective amendment shall be deemed to be a
new registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

                (3)     To remove from registration by means of a post-effective
amendment any of the securities being registered which remain unsold at the
termination of the offering.

        (b)     The undersigned Registrant hereby undertakes that, for purposes
of determining any liability under the Securities Act, each filing of the
Registrant's annual report pursuant to Sec-



<PAGE>   5

tion 13(a) or Section 15(d) of the Exchange Act (and, where applicable, each
filing of an employee benefit plan's annual report pursuant to Section 15(d) of
the Exchange Act) that is incorporated by reference in the registration
statement shall be deemed to be a new registration statement relating to the
securities offered therein, and the offering of such securities at that time
shall be deemed to be the initial bona fide offering thereof.

        (c)     Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the Registrant pursuant to the Registrant's Bylaws, indemnification
agreements, or otherwise, the Registrant has been advised that in the opinion of
the Securities and Exchange Commission such indemnification is against public
policy as expressed in the Act and is, therefore, unenforceable. In the event
that a claim for indemnification against such liabilities (other than the
payment by the Registrant of expenses incurred or paid by a director, officer or
controlling person of the Registrant in the successful defense of any action,
suit or proceeding) is asserted by such director, officer or controlling person
in connection with the securities being registered, the Registrant will, unless
in the opinion of its counsel the matter has been settled by controlling
precedent, submit to a court of appropriate jurisdiction the question whether
such indemnification by it is against public policy as expressed in the Act and
will be governed by the final adjudication of such issue.



<PAGE>   6

                                   SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, the
Registrant, Harmonic Inc., a Delaware corporation, certifies that it has
reasonable grounds to believe that it meets all of the requirements for filing
on Form S-8 and has duly caused this registration statement to be signed on its
behalf by the undersigned, thereunto duly authorized, in the City of Sunnyvale,
State of California, on September 7, 1999.


                                        HARMONIC INC.

                                        By: /s/ Anthony J. Ley
                                           -------------------------------------
                                           Anthony J. Ley, Chairman of the
                                           Board, President and Chief
                                           Executive Officer



<PAGE>   7

                                POWER OF ATTORNEY

        KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature
appears below constitutes and appoints Anthony J. Ley and Robin N. Dickson,
jointly and severally, his attorneys-in-fact, each with the power of
substitution, for him in any and all capacities, to sign any amendments to this
Registration Statement on Form S-8, and to file the same, with exhibits thereto
and other documents in connection therewith, with the Securities and Exchange
Commission, hereby ratifying and confirming all that each of said
attorneys-in-fact, or his substitute or substitutes, may do or cause to be done
by virtue hereof.

        Pursuant to the requirements of the Securities Act of 1933, this
registration statement has been signed by the following persons in the
capacities and on the date indicated.

<TABLE>
<CAPTION>
            SIGNATURE                                      TITLE                         DATE
            ---------                                      -----                         ----

<S>                              <C>                                          <C>
/s/ Anthony J. Ley               Chairman of the Board, President             September 7, 1999
-----------------------------    and Chief Executive Officer
   (Anthony J. Ley)              (Principal Executive Officer)


/s/ Robin N. Dickson             Chief Financial Officer                      September 7, 1999
-----------------------------    (Principal Financial and
   (Robin N. Dickson)            Accounting Officer)


/s/ E. Floyd Kvamme              Director                                     September 7, 1999
-----------------------------
   (E. Floyd Kvamme)


/s/ David A. Lane                Director                                     September 7, 1999
-----------------------------
   (David A. Lane)


/s/ Barry D. Lemieux             Director                                     September 7, 1999
-----------------------------
   (Barry D. Lemieux)


/s/ Moshe Nazarathy              Director                                     September 7, 1999
-----------------------------
   (Moshe Nazarathy)


/s/ Michel L. Vaillaud           Director                                     September 7, 1999
-----------------------------
   (Michel L. Vaillaud)
</TABLE>



<PAGE>   8

                       SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549

                                 --------------
                                    EXHIBITS
                                 --------------

                       REGISTRATION STATEMENT ON FORM S-8

                                  HARMONIC INC.

                               SEPTEMBER 7, 1999



<PAGE>   9

                                INDEX TO EXHIBITS

<TABLE>
<CAPTION>
                                                                                    Sequentially
       Exhibit                                                                        Numbered
       Number                           Description                                      Page
       -------  ---------------------------------------------------------           ------------
<S>             <C>                                                                 <C>
        5.1     Opinion of Wilson Sonsini Goodrich & Rosati, Professional
                Corporation.

        10.1    1995 Stock Plan, as amended.

        10.2    1999 Nonstatutory Stock Option Plan.

        23.1    Consent of PriceWaterhouseCoopers LLP.

        23.2    Consent of Wilson Sonsini Goodrich & Rosati, Professional
                Corporation (included in Exhibit 5.1).

        24.1    Power of Attorney (See page II-4).
</TABLE>
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 15066}]
{"company-data": {"conformed-name": "HARMONIC INC", "cik": "0000851310", "assigned-sic": "3663", "irs-number": "770201147", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-86649", "film-number": "99706889"}, "business-address": {"street1": "549 BALTIC WAY", "city": "SUNNYVALE", "state": "CA", "zip": "94089", "phone": "4085422500"}, "former-company": {"former-conformed-name": "HARMONIC LIGHTWAVES INC", "date-changed": "19950404"}}
1

   As filed with the Securities and Exchange Commission on September ___, 1999
                         Registration No. 333-__________

================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                             ----------------------

                                    FORM S-8
                             REGISTRATION STATEMENT
                        UNDER THE SECURITIES ACT OF 1933

                             ----------------------

                                  HARMONIC INC.
             (Exact name of registrant as specified in its charter)
                      (formerly Harmonic Lightwaves, Inc.)

                DELAWARE                               77-0201147
      (State or other jurisdiction                    (IRS Employer
            of incorporation)                      Identification No.)

                                 549 Baltic Way
                           Sunnyvale, California 94089
                    (Address of principal executive offices)

                             ----------------------

                                 1995 Stock Plan
                       1999 Nonstatutory Stock Option Plan
                            (Full Title of the Plans)

                             ----------------------

                                 ANTHONY J. LEY
    CHAIRMAN OF THE BOARD OF DIRECTORS, PRESIDENT AND CHIEF EXECUTIVE OFFICER
                                  HARMONIC INC.
                                 549 BALTIC WAY
                           SUNNYVALE, CALIFORNIA 94089
                                 (408) 542-2500
           (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)

                                   Copies to:
                             JEFFREY D. SAPER, ESQ.
                        WILSON SONSINI GOODRICH & ROSATI
                            Professional Corporation
                               650 Page Mill Road
                           Palo Alto, California 94304
2
========================================================================================================
                                                        Proposed
                                                         Maximum
                Title of                   Amount       Offering            Proposed          Amount of
              Securities to                to be        Price Per       Maximum Aggregate   Registration
              be Registered              Registered     Share(1)          Offering Price        Fee(2)
--------------------------------------------------------------------------------------------------------
Common Stock (par value $0.001 par        580,000       $105.9375        $61,443,750.00      $17,081.36
value) reserved for issuance under
the 1995 Stock Plan

Common Stock (par value $0.001 par        200,000       $105.9375        $21,187,500.00      $ 5,890.13
value) reserved for issuance under
the 1999 Nonstatutory Stock Option Plan
========================================================================================================
(1)     Estimated pursuant to Rule 457(h) of the Securities Act of 1933, as
        amended, solely for the purpose of calculating the registration fee. The
        proposed maximum offering price per share with respect to each of the
        580,000 shares reserved for issuance under the 1995 Stock Plan and the
        200,000 shares reserved for issuance under the 1999 Nonstatutory Stock
        Option Plan was determined by reference to the fair market value of the
        Common Stock (the "FMV"), or, the average of the high and low price
        reported in the Nasdaq National Market on August 30, 1999.

(2)     Amount of Registration Fee was calculated pursuant to Section 6(b) of
        the Securities Act of 1933, which states that the fee shall be "$278 per
        $1 million" of the maximum aggregate price at which such securities are
        proposed to be offered. The Registration Fee is therefore calculated by
        multiplying the aggregate offering or sales amount by 0.000278.
3

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3. INFORMATION INCORPORATED BY REFERENCE.

        There are hereby incorporated by reference in this Registration
Statement the following documents and information heretofore filed with the
Securities and Exchange Commission:

        (a)     The Registrant?s Annual Report on Form 10-K for the year ended
December 31, 1998 filed pursuant to Section 13(a) or 15(d) of the Securities
Exchange Act, as amended (the ?Exchange Act?).

        (b)     The Registrant?s quarterly reports on Form 10-Q for the quarter
ended April 2, 1999 and the quarter ended July 2, 1999 filed pursuant to Section
13(a) or 15(d) of the Exchange Act.

        (c)     The description of the Registrant's Common Stock contained in
the Registrant's Registration Statement on Form 8-A dated April 6, 1995, filed
pursuant to Section 12 of the Securities Exchange Act of 1934, as amended,
including any amendment or report filed for the purpose of updating such
description.

        All documents filed by the Registrant pursuant to Sections 13(a), 13(c),
14 and 15(d) of the Exchange Act after the date of this registration statement
and prior to the filing of a post-effective amendment which indicates that all
securities offered have been sold or which deregisters all securities then
remaining unsold, shall be deemed to be incorporated by reference in this
registration statement and to be part hereof from the date of filing such
documents.

ITEM 4. DESCRIPTION OF SECURITIES.

        Not applicable.

ITEM 5. INTERESTS OF NAMED EXPERTS AND COUNSEL.

        Not applicable.

ITEM 6. INDEMNIFICATION OF DIRECTORS AND OFFICERS.

        Section 145 of the Delaware General Corporations Law authorizes a court
to award, or a corporation's Board of Directors to grant, indemnification to
directors and officers in terms sufficiently broad to permit such
indemnification under certain circumstances for liabilities (including
reimbursement for expenses incurred) arising under the Securities Act. Article
VI of the Company's Bylaws provides for the mandatory indemnification of its
directors, officers, employees and other agents to the maximum extent permitted
by Delaware General Corporation Law, and the Company
4

has entered into agreements with its officers, directors and certain key
employees implementing such indemnification.

ITEM 7. EXEMPTION FROM REGISTRATION CLAIMED.

        Not applicable.

ITEM 8. EXHIBITS.
Exhibit
              Number
              ------
5.1     Opinion of Wilson Sonsini Goodrich & Rosati,
                        Professional Corporation, as to the legality of
                        securities being registered.

                10.1    1995 Stock Plan, as amended.

                10.2    1999 Nonstatutory Stock Option Plan.

                23.1    Consent of Independent Accountants.

                23.2    Consent of Counsel (included in Exhibit 5.1).

                24.1    Power of Attorney (see page II-4).
ITEM 9. UNDERTAKINGS.

        (a)     The undersigned Registrant hereby undertakes:

                (1)     To file, during any period in which offers or sales are
being made, a post-effective amendment to this registration statement to include
any material information with respect to the plan of distribution not previously
disclosed in the registration statement or any material change to such
information in the registration statement.

                (2)     That, for the purpose of determining any liability under
the Securities Act, each such post-effective amendment shall be deemed to be a
new registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

                (3)     To remove from registration by means of a post-effective
amendment any of the securities being registered which remain unsold at the
termination of the offering.

        (b)     The undersigned Registrant hereby undertakes that, for purposes
of determining any liability under the Securities Act, each filing of the
Registrant's annual report pursuant to Sec-
5

tion 13(a) or Section 15(d) of the Exchange Act (and, where applicable, each
filing of an employee benefit plan's annual report pursuant to Section 15(d) of
the Exchange Act) that is incorporated by reference in the registration
statement shall be deemed to be a new registration statement relating to the
securities offered therein, and the offering of such securities at that time
shall be deemed to be the initial bona fide offering thereof.

        (c)     Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the Registrant pursuant to the Registrant's Bylaws, indemnification
agreements, or otherwise, the Registrant has been advised that in the opinion of
the Securities and Exchange Commission such indemnification is against public
policy as expressed in the Act and is, therefore, unenforceable. In the event
that a claim for indemnification against such liabilities (other than the
payment by the Registrant of expenses incurred or paid by a director, officer or
controlling person of the Registrant in the successful defense of any action,
suit or proceeding) is asserted by such director, officer or controlling person
in connection with the securities being registered, the Registrant will, unless
in the opinion of its counsel the matter has been settled by controlling
precedent, submit to a court of appropriate jurisdiction the question whether
such indemnification by it is against public policy as expressed in the Act and
will be governed by the final adjudication of such issue.
6

                                   SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, the
Registrant, Harmonic Inc., a Delaware corporation, certifies that it has
reasonable grounds to believe that it meets all of the requirements for filing
on Form S-8 and has duly caused this registration statement to be signed on its
behalf by the undersigned, thereunto duly authorized, in the City of Sunnyvale,
State of California, on September 7, 1999.

                                        HARMONIC INC.

                                        By: /s/ Anthony J. Ley
                                           -------------------------------------
                                           Anthony J. Ley, Chairman of the
                                           Board, President and Chief
                                           Executive Officer
7

                                POWER OF ATTORNEY

        KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature
appears below constitutes and appoints Anthony J. Ley and Robin N. Dickson,
jointly and severally, his attorneys-in-fact, each with the power of
substitution, for him in any and all capacities, to sign any amendments to this
Registration Statement on Form S-8, and to file the same, with exhibits thereto
and other documents in connection therewith, with the Securities and Exchange
Commission, hereby ratifying and confirming all that each of said
attorneys-in-fact, or his substitute or substitutes, may do or cause to be done
by virtue hereof.

        Pursuant to the requirements of the Securities Act of 1933, this
registration statement has been signed by the following persons in the
capacities and on the date indicated.
SIGNATURE                                      TITLE                         DATE
            ---------                                      -----                         ----
/s/ Anthony J. Ley               Chairman of the Board, President             September 7, 1999
-----------------------------    and Chief Executive Officer
   (Anthony J. Ley)              (Principal Executive Officer)

/s/ Robin N. Dickson             Chief Financial Officer                      September 7, 1999
-----------------------------    (Principal Financial and
   (Robin N. Dickson)            Accounting Officer)

/s/ E. Floyd Kvamme              Director                                     September 7, 1999
-----------------------------
   (E. Floyd Kvamme)

/s/ David A. Lane                Director                                     September 7, 1999
-----------------------------
   (David A. Lane)

/s/ Barry D. Lemieux             Director                                     September 7, 1999
-----------------------------
   (Barry D. Lemieux)

/s/ Moshe Nazarathy              Director                                     September 7, 1999
-----------------------------
   (Moshe Nazarathy)

/s/ Michel L. Vaillaud           Director                                     September 7, 1999
-----------------------------
   (Michel L. Vaillaud)
8

                       SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549

                                 --------------
                                    EXHIBITS
                                 --------------

                       REGISTRATION STATEMENT ON FORM S-8

                                  HARMONIC INC.

                               SEPTEMBER 7, 1999
9

                                INDEX TO EXHIBITS
Sequentially
       Exhibit                                                                        Numbered
       Number                           Description                                      Page
       -------  ---------------------------------------------------------           ------------
5.1     Opinion of Wilson Sonsini Goodrich & Rosati, Professional
                Corporation.

        10.1    1995 Stock Plan, as amended.

        10.2    1999 Nonstatutory Stock Option Plan.

        23.1    Consent of PriceWaterhouseCoopers LLP.

        23.2    Consent of Wilson Sonsini Goodrich & Rosati, Professional
                Corporation (included in Exhibit 5.1).

        24.1    Power of Attorney (See page II-4).