High-power efficient continuous-wave TEM_00 intracavity frequency-doubled diode-pumped Nd:YLF laser

We describe experimental results with a diode-pumped, intracavity-doubled cw Nd:YLF laser in multilongitudinal mode and TEM_00 spatial transverse mode with a critical phase-matched lithium triborate crystal. Taking into account the thermal effects of Nd:YLF, energy-transfer upconversion, and the thermal fracture limit, we set up a power-scaling model to optimize and design a fundamental diode-pumped Nd:YLF laser. A highly efficient second-harmonic laser was achieved, based on the optimized cavity design. A second-harmonic-generation output power of 20.5 W at a wavelength of 527 nm was obtained at an incident pump power of 60 W, corresponding to an optical-to-optical efficiency of 34.2%. The TEM_00 mode green laser operates at a measured M^2 parameter of 1.2. The instability of the green laser power is less than +-1% RMS.