FREQUENCY-MODULATION OF THE SUPERCONDUCTING PARALLEL-PLATE MICROWAVE RESONATOR BY LASER IRRADIATION

We have studied the effect of chopped laser irradiation (lambda(L)=514 nm) on the resonant frequency (f(0) approximate to 5.4 GHz) of a supe rconducting parallel-plate resonator (PPR) consisting of two thin epit axial YBa2Cu3O7-x films. We demonstrate that laser irradiation shifts the resonant frequency of the PPR with negligible change of quality fa ctor. Photoinduced deviation of f(0) strongly depends on the chopping frequency and increases linearly with light intensity. The effect of i llumination is attributed to the photoinduced change of the kinetic in ductance due to laser heating. This effect may be used to produce phas e modulation of the superconducting transmission lines. (C) 1994 Ameri can Institute of Physics.