Controlled energy extraction and sharp nanosecond pulses from an HF amplifier

We report complete spatial control of laser energy extracted from an electron-beam-initiated HF amplifier. Control was achieved by application of a weak oscillator beam, which, by extraction of all of the available energy, overcame amplified spontaneous emission. In a separate experiment, temporal control was also demonstrated. Short (4-ns) sharp (contrast ∼20) amplified pulses were obtained by rapid polarization rotation and selective reflection in the amplified beam.