MODELING THE GAAS-MESFETS RESPONSE TO MODULATED LIGHT AT RADIO AND MICROWAVE-FREQUENCIES

In recent years, the usefulness of the MESFET as an optically sensitiv e microwave element on MMIC's has generated much interest. A theoretic al model for the device under steady illumination has been developed p reviously by the authors. This paper presents an extension of that mod el to include sinusoidally modulated illumination up to the microwave range. The dependance of the response on the bias conditions, the wave length, intensity and modulation frequency of the optical input, and t he particulars of device structure are incorporated in the model. The importance of the internal photovoltaic effect, not properly accounted for in previous works, is emphasized. The theoretical model is valida ted by experimental results.