To construct an electronically controllable phase array system in the millimeter-wave region, one needs switches, phase shifters, and modulators which are operable at speeds of ~ 1 nsec and with a time precision of several picoseconds. The only technique possessing this speed capability uses an optically injected electron-hole plasma in a semiconductor waveguide to control the phase shift and attenuation of the millimeter waves. In our early experiments, ultrafast millimeter-wave switching without jitter has been demonstrated with a response time of 40 psec.1 The modulation of millimeter-wave signals at 94 GHz with a repetition rate of ≥200 MHz has also been reported. To design optically controllable millimeter-wave components, it is necessary to understand in detail the behavior of the electron-hole plasma in a semiconductor. For this purpose, we will report on the newly developed techniques which can follow the dynamic evolution of the electron-hole plasma in the semiconductor with excellent time resolution.
© 1984 Optical Society of AmericaPDF Article