Frequency Upconversion of Semiconductor Diode Lasers

A number of different techniques have been used for nonlinear frequency upconversion of near-infrared semiconductor diode lasers. Intracavity frequency doubling of a diode-laser-pumped 946-nm Nd:YAG laser led to the generation of 9.5 mW of blue 473-nm power. A special electronic servo technique was devised to lock the output frequency of a single-mode GaAlAs diode laser to a monolithic KNbO3 resonator. Using the approach, 41 mW of 428-nm output were obtained with an electrical-to-optical conversion efficiency of about 10 percent. Strained-layer InGaAs/GaAs diode laser operating at about 1 micron have been fabricated for noncritically phase-matched frequency doubling in KTiOPO4. A 802-nm GaAlAs diode laser was used for upconversion pumping of a YLiF4:Er(3+) laser which operates at 551 nm with a threshold power of 50 mW at 77 K.