Experimental verification of nonuniform plasma layer model for quartz-silicon image guide phase shifters

The optical control of millimeter waves in image guides composed of a quartz-silicon sandwich structure is investigated for use at W-band frequencies. The controllability of the dispersion characteristics is confirmed both theoretically and experimentally for single-moded guides using a pulse-modulated high-power semiconductor laser source. For the first time, measurement results of the frequency response of the phase shift are presented and, in addition to top side illumination, lateral illumination of the image guide is investigated. Differences between experimental and theoretical data based on a one-dimensional diffusion-controlled nonuniform plasma layer model are attributed to an inhomogeneity of the plasma distribution along the broadside of the silicon strip due to the impact of a huge surface recombination at the cutting area of the silicon strip.