A hybrid fiber/solid-state regenerative amplifier with tunable pulse widths for satellite laser ranging

A fiber/solid-state hybrid seeded regenerative amplifier capable of achieving high output energy with tunable pulse widths has been developed for satellite laser ranging applications. The regenerative amplifier cavity utilizes a pair of Nd: YAG zigzag slabs oriented orthogonally to one another in order to symmetrize thermal lensing effects and simplify optical correction schemes. The seed laser used is a fiber-coupled 1064 nm narrowband (<0.02 nm) diode laser which is intensity modulated by a fiber Mach-Zender electrooptic modulator, enabling continuously tunable seed pulse widths in the 0.2 - 2.0 ns range. The seed laser pulse energy entering the regenerative amplifier cavity is ~10 pJ, and is amplified to ~1.6 mJ after 37 round trips, representing a gain of ~82 dB. When seeded with 200 ps pulses at a 2 kHz repetition rate, the regenerative amplifier produces >2 W of frequency-doubled output (>1 mJ/pulse at 532 nm).