Single-frequency CaWO4 Raman amplifier at 1178 nm.

Single-frequency crystalline Raman amplifications at 1178 nm were demonstrated. The seeding laser was generated from a single-frequency continuous wave fiber Raman amplifier. Three stages of Raman amplifications from CaWO4 single crystals were realized with a pulsed 1064 nm Nd:YAG laser as the pumping source. The final output pulse energy at 1178 nm was 26.7 mJ, and the pulse width was 2.9 ns, corresponding to a peak power of 5.2 MW. The overall Raman amplification ratio was up to 4.6×10(6). The linewidth was less than 500 MHz.