Optical-microwave interaction modeling in high-temperature superconductingfilms

Optical-microwave interaction in high-T-c superconductors is investigated f or performing basic optoelectronic functions in cryogenic environment. A fa st bolometric photoresponse in conjunction with the unique electrical prope rties of high-temperature superconductor (HTS) materials allows us to explo re a series of novel optoelectronic devices with low-noise/low-power and hi gh-speed/high-frequency characteristics. After reviewing the HTS photorespo nse categories, we describe the fast bolometric photoresponse and its condi tion with heat transfer analysis. The analytical solution of heat diffusion equation for an HTS strip mounted on a substrate will be presented for thr ee different type of optical sources. Then the effect of optical irradiatio n will be incorporated in the two-fluid model by thermomodulation concept i n order to model the interaction of optical radiation with electrical signa l. The current-field relationship and the supercurrent response time are ev aluated in the presence of both optical and electrical signals. Our numeric al simulations for YBaCuO film will demonstrate the possibility of RF harmo nic generation when the laser beam is modulated by the RF signal in the pre sence of de bias current and RF signal mixing when the HTS film is fed by a time-harmonic microwave source. The developed model can also be used to st udy optical control and tunability techniques for HTS microwave devices for analog signal processing.