Widely tunable continuous-wave solid-state red laser source using periodically-poled lithium niobate

In this work we have generated widely-tunable continuous-wave (CW) red light by second-harmonic generation (SHG) of the output of a Cr4+:forsterite laser, tunable from 1.206 to 1.320 mu m, using quasi-phasermatching (QPM) in periodically-poled lithium niobate (PPLN). For a given grating period in the PPLN, a combination of Cr4+:forsterite pump wavelength tuning and PPLN temperature tuning up to 200 degrees C provided continuous SHG tuning over a wavelength range of approximately 14 nm in the red. By translating the PPLN crystal to other periods, we have demonstrated SHG over the entire tuning range of the pump laser, yielding tunable CW output from 603 to 660 mu with maximum output powers of approximately 5 mW for a typical Cr4+:forsterite pump power of 500 mW.