A HIGH-POWER LAMP-PUMPED LNA LASER WITH THERMALLY TUNED ETALON

This report describes an arc-lamp pumped, tunable, continuous-wave LNA laser with improved output efficiency, suitable for optical pumping of helium. Using thermal tuning of intracavity etalons instead of angle tuning reduces losses caused by walk-off effects and provides continuous frequency scanning without a significant decrease in laser power. We obtain an output power of 4 W in a linewidth of 2.5 GHz with the laser wavelength tuned to the 1.083-mu-m absorption line of metastable helium. This result represents a fourfold gain in efficiency compared with conventional tuning by tilting. The laser provides efficient polarization of helium by optical pumping in various applications, such as nuclear spin polarization of He-3 and spin-polarized electron sources.