High beam quality and high power dual-wavelength laser with VRM

The double wavelenghs short pulse laser was developed with the high mode volume and variable reflectivity mirror(VRM). The thermal lens and the thermal birefringence produced by diode-lasers pumped rod laser medium was compensated, which presented a short-pulse energy of 140 mJ and 1 064 nm laser output with a pulse width of 17.76 ns at a repetition rate of 500 Hz. The beam quality value was M21.6, and the energy instability(RMS) value of 20 minutes was less than 0.3%. The result of resonator was corresponded with Master Oscillator Power-Amplifier(MOPA) technology, but it was close and neat. The maximum laser energy of 96 mJ at 532 nm was demonstrated by extra-cavity second-harmonic generation(SHG) with type-Ⅱ angle phase-matched GTR-KTP crystal, the KTP crystals with resistance to grey trace effect was grown by hydrothermal method. The maximum efficiency of SHG was 68.6%, and the beam quality value was M22.1. The 1 064 nm and 532 nm laser were output at same axis with energy regulation.