OPTICALLY PUMPED SEMICONDUCTOR LASER WITH MODE TRACKING

摘要

An intra-cavity doubled OPS-laser (10) has a laser-resonator (22) including a birefringent filter (BRF) for coarse wavelength-selection, and an optically nonlinear (ONL) crystal (26) arranged for type-II frequency-doubling and fine wavelength-selection. Laser-radiation circulates in the laser-resonator (22) at one of a range of fundamental wavelengths dependent on the resonator length. The ONL crystal (26) has a transmission peak- wavelength dependent on the crystal temperature. Reflection of circulating radiation from the BRF is monitored. The reflection is at a minimum when the ONL crystal (26) transmission-peak wavelength is at the circulating radiation wavelength. The temperature of the ONL crystal (26) is selectively varied to maintain the monitored reflection at about a minimum.