A high-power RF switching device employs a semiconductor wafer positioned
in the third port of a three-port RF device. A controllable source of
directed energy, such as a suitable laser or electron beam, is aimed at
the semiconductor material. When the source is turned on, the energy
incident on the wafer induces an electron-hole plasma layer on the wafer,
changing the wafer's dielectric constant, turning the third port into a
termination for incident RF signals, and. causing all incident RF signals
to be reflected from the surface of the wafer. The propagation constant of
RF signals through port 3, therefore, can be changed by controlling the
beam. By making the RF coupling to the third port as small as necessary,
one can reduce the peak electric field on the unexcited silicon surface
for any level of input power from port 1, thereby reducing risk of
damaging the wafer by RF with high peak power. The switch is useful to the
construction of an improved pulse compression system to boost the peak
power of microwave tubes driving linear accelerators. In this application,
the high-power RF switch is placed at the coupling iris between the
charging waveguide and the resonant storage line of a pulse compression
system. This optically controlled high power RF pulse compression system
can handle hundreds of Megawatts of power at X-band.
