Pulsed operation of an optoelectronic finline switch

Three optically switched finline structures on semiconducting substrates are described. The first is a finline on a lossless silicon oxide substrate with a thin-film of polysilicon, the second is on a highly resistive silicon substrate, and the third is on an intrinsic gallium arsenide substrate. The insertion loss of these finlines is measured over the full 26.5-GHz-40-GHz (Ka) band. A pulsed laser diode is used to create an electron-hole plasma in the slot region, changing the propagation properties of a millimeter-wave passing through the excited region. The insertion loss without illumination and the attenuation it causes are measured. All the structures show a relatively small insertion loss that can be further decreased by an improved choke structure and by material taper design.<>