We report an efficient, high-power, cw, 629-nm laser source based on a diode-pumped Nd:YAG laser and a periodically poled lithium niobate (PPLN) frequency converter. This device integrates two separate frequency-conversion steps in a single crystal, taking advantage of the ability to fabricate PPLN with nearly arbitrary grating periods and phase-matching temperatures. This device uses a single PPLN crystal that has two grating regions in series. The first region quasi-phase matches a standard optical parametric oscillator process (1064 nm?1540 nm+3450 nm), and the second region quasi-phase matches a sum-frequency process whereby the pump and the signal light make red light (1064 nm+1540 nm?629 nm). Using a four-mirror ring cavity, we were able to convert 21% of the 1064-nm pump to 629-nm output, yielding 2.5 W of red output with 11.8 W of input.
© 1998 Optical Society of AmericaPDF Article