Compact laser amplifier based on SrF2 crystal

We report a two-stage two-pass compact amplifier based on SrF₂ crystal with gains of over 10⁶. The shape of the crystal is irregular, so that the gain length is increased and parasitic oscillation is suppressed. The amplified spontaneous emission (ASE) and spectral characteristic of amplifier are analyzed. The results show that ASE increases with the pump power, and the simultaneous use of different crystals types can increase the output bandwidth. This work has a potential application in high-power / high-energy laser devices.