The interest in fast risetime, high power photoconductive devices stems from
several potential applications including pulse, impulse, and high power microwave
generation [1, 2]. As the voltage becomes large and the switching speed becomes
extremely fast, the generation of high power electrical pulses using photoconductive
devices becomes very complicated because of effects such as surface flash-over,
stray inductance, stray capacitance, and abrupt impedance transitions. Two ap-
proaches were taken to produce maximum output voltage amplitude without degradation
in switch risetime. A coaxial transmission line with a switch holder filled with a
high dielectric strength liquid was fabricated for long pulsewidths ( 2 ns) . For
the narrow pulsewidths ( 2 ns) a quasi-radial transmission line was fabricated.
By incorporating a photoconductive bulk GaAs device with opposite gridded elec-
trodes into these specially designed energy storage elements, and illuminating the
switch with a mode-locked Nd:YAG laser, electrical pulses with risetimes of several
picoseconds have been realized.