Abstract

A tunable pulsed color center laser using additively colored OH⁻-doped NaCl is discussed. The laser has produced output energies exceeding 8 mJ in 20-ns pulses. This energy is four times greater than that reported for previous pulsed color center lasers. More significantly, this performance has been achieved with a room-temperature crystal. The laser has a tuning range which extends from 1.37 to 1.77 µm. Based on the observed spectral properties of the center¹ and the laser tuning curve, laser action at room temperature is tentatively ascribed to $F_2^{+}$ centers. The OH ions are necessary for producing a sufficient $F_2^{+}$ population. A positive branch unstable resonator was used, which, because of a 50% reflective output coupler, produced a filled-in mode. The laser was operated for up to 40 h during which time the output power faded 40%. Crystal preparation, cavity and pump scheme, fading mechanisms, and laser results are explained. In addition, cryogenic and room-temperature operation are compared.

© 1987 Optical Society of America