Regenerative Amplifier For The Omega Laser System

We present the requirements, design, and experimental results for a negative feedback-controlled Nd:YLF regenerative amplifier (regen) for the OMEGA laser system. This externally synchronizable regen boosts the energy of temporally shaped optical pulses from the subnanojoule to the submillijoule energy level with a measured long-term output energy stability of 0.2% rms. To our knowledge this represents the highest energy stability ever demonstrated for a millijoule-level laser system, either flashlamp pumped or diode pumped. In addition to the excellent stability and reproducibility, the regen output is very insensitive to the injected pulse energy and the temporal distortions due to the negative feedback are immeasurable. Four regenerative amplifiers equipped with this negative feedback system have operated flawlessly on OMEGA over the past two-year period.