Optical control of millimeter wave high T c superconducting quasi-optical bandpass filters

Abstract
The optical response of YBa2Cu3O7 high Tc superconducting quasi‐optical millimeter wave bandpass filters operating at W band (75–110 GHz) has been investigated under various conditions of illumination. Radiation from a cw Ar+ laser (514.5 nm) and a frequency‐doubled Nd:YAG laser (532.8 nm, 120 ps) was used to induce a shift in the resonant frequency of the filter. A shifted Lorentzian line shape function model was used to estimate the magnitude of the light‐induced changes. Shifts of the filter’s resonance frequency on the order of 0. 1 MHz were induced by the laser effects on the superconductor pair population.