Filing Pursuant to Rule 424(b)(2)
                                            Registration Statement No. 333-33966


                              PROSPECTUS SUPPLEMENT
                      (TO PROSPECTUS DATED APRIL 12, 2000)

                                  COMMON STOCK

                                APA OPTICS, INC.


         You should read this prospectus supplement and the accompanying
prospectus carefully before you invest. Both documents contain information you
should consider when making your investment decision.

         See "Risk Factors" beginning on page 5 of the prospectus to read about
factors you should consider before buying shares of the common stock.

PLAN OF DISTRIBUTION

         Pursuant to this prospectus supplement, we are offering 148,148 shares
of our common stock to Strong River Investments, Inc., an institutional
investor, through Ladenburg Thalmann & Co., Inc. The common stock will be
purchased at a negotiated purchase price of $2,000,000. We will pay Ladenburg a
commission of $60,000 on this sale. We have agreed to indemnify Ladenburg
against liabilities, including liabilities under the Securities Act of 1933.

USE OF PROCEEDS

         The net proceeds to us from this sale will be approximately $1,940,000.
We plan to use the net proceeds for general corporate purposes, including:

         *   Expansion of production facilities
         *   Sales and marketing of our DWDM-based product line
         *   Working capital

MARKET FOR OUR COMMON STOCK

         On June 15, 2000, the last reported sales price of our common shares on
the Nasdaq SmallCap Market was $14.625 per share. Our common stock is listed on
the Nasdaq SmallCap Market under the symbol "APAT."

         As of June 15, 2000 and before the issuance of shares pursuant to this
prospectus supplement, we have 9,323,230 shares of common stock outstanding.

GENERAL

         You should rely only on the information provided or incorporated by
reference in this prospectus supplement and the prospectus. We have not
authorized anyone else to provide you with different information. You should not
assume that the information in this prospectus supplement is accurate as of any
date other than the date on the front of these documents.



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

         The Securities and Exchange Commission and state securities regulators
have not approved or disapproved these securities, or determined if this
prospectus is truthful or complete. Any representation to the contrary is a
criminal offense.

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

             The date of this prospectus supplement is June 15, 2000


                                       2