Novel external CW frequency doubling of semiconductor lasers to generate 488 nm

We report a simple and compact all-solid-state laser generating 488 nm light with continuously variable output power in the range from 1 mW to over 120 mW. We frequency double single frequency radiation from an external cavity semiconductor laser in a periodically poled MgO:LiNbO 3 ridge waveguide. The laser maintains a high quality TEM 00 circular beam with M 2 < 1.1 and very low r.m.s. noise of less than 0.06% over the entire range of output power. Less than 0.1% peak-to-peak output power variation was measured during 14 hours of operation. No degradation of the conversion efficiency has been observed for operation at an output power of 70 mW for 3.5 months. The prototype laser has a small footprint of 5x8 cm.