Laser-Triggered Avalanche-Transistor Voltage Generator for a Picosecond Streak Camera

Direct optical triggering of an avalanche transistor with a short laser pulse has been demonstrated. In some applications this system provides a compact low-jitter replacement for a laser-triggered spark gap. The technique has been applied to generating the gating and sweep voltages in a picosecond streak camera for laser pulse diagnostics where it eliminates the need for multiple beam splitters and long delays. The ``trigger'' avalanche transistor was placed as one of a series string of avalanche transistors. A portion of the switched-out laser pulse to be diagnosed was focused onto the trigger transistor chip. Nanosecond-rise kilovolt waveforms are thus generated with time jitter of the entire system being less than 100 psec.