COMPACT SINGLE-FREQUENCY DIODE-PUMPED CR-LISAF LASERS

We report on the performance of diode-pumped Cr:LiSAF lasers with coup led optical cavities for single-frequency operation and wavelength tun ing. One of these lasers consists of a 500 mu m long, highly doped Cr: LiSAF crystal (one surface is HR coated, the other uncoated) and a 0.3 % flat output coupler positioned at a distance of 10 mu m from the unc oated crystal surface. Pumped by 30 mW of 670 nm diode laser radiation this laser generated single-frequency radiation with a power of 5 mW and a spectral width of 3 MHz at wavelengths within the tuning range o f 860 to 900 nm. A second short cavity Cr:LiSAF laser was operated wit h an external grating resonator. This laser produced a single-frequenc y output of 16 mW with a linewidth of similar to 1 MHz. The wavelength was tunable in the range of 800-970 nm. The performance of these lase rs is analyzed by characterizing the optical cavity (which is determin ed by the thermally induced changes of the refractive index and the un isotropic thermal expansion of the laser crystal), by integrating the relevant rate equations, and by solving the electric field equations f or the coupled cavities. (C) 1997 Elsevier Science B.V.