High-repetition-rate Cr:Nd:GSGG active-mirror amplifier

We have designed, constructed, and operated a 3.8-cm clear-aperture Cr:Nd:GSGG active-mirror amplifier. We believe this to be the first active mirror that uses a crystalline host and the largest-aperture Cr:Nd:GSGG amplifier yet reported. We have measured a small-signal gain of 1.6. The wave front has been measured and found to be less than three waves of defocus at repetition rates of up to 10 Hz. Surface displacements were measured and compared with theory. Depolarization was less than 2.5% at maximum power at any location in the clear aperture.