Optically controlled millimeter-wave parallel guide directional coupler

Optical control of the parallel guide coupler is based on the mode selective photoinduced change of the attenuation and phase constants as well as on the lumped power transfer between the two lowest order modes at the discontinuities at the beginning and the end of the active section. Apart from the application as a directional coupler with controllable coupling characteristics, the structure can be used as a cross-over switch without the capacitive leakage problem of laser-controllable gap structures in stripline technology. The results achieved in this work can be transferred to the lower THz range to a large extend via scaling the dimensions of the structure as long as the collision frequencies of the photoinduced carriers are higher than the signal angular frequency.