Nanosecond switching and amplification of multiline HF laser pulses

Electrooptic gating and amplification of Pulses with durations from 1 to 5 ns were accomplished with a pulsed HF chemical laser system using SF6-hydrocarbon media and transverse-discharge energization. The system comprised an apertured, pin-discharge multiline oscillator, a MgF2Rochon prism polarizer, a Pockels-effect, fast electrooptic switch, a 5:1 magnifying telescope, and a 22-mm diam, ∼ 5-MW TEA amplifier, together with several arrangements of polarization analyzer elements. A 5-mm, square-sectioned electrooptic crystal of CdTe or LiNbO3yielded polarization contrast ratios of under zero and half-wave electric fields. Without other measures, this contrast in gated amplitude was diminished in passage through the partially gain-saturated amplifier. However, 80:1 amplitude contrast in the gated, amplified pulse was preserved when file full oscillator beam intensity was used continuously to control the amplifier gain. This was done either with a polarization discriminator placed downstream of the amplifier, or with the two polarized components from the gate taking separate directions, intersecting within the amplifier.