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Efficient scalable optically pumped HBr laser

A concept combining the advantages of solid-state and gas-laser technologies is being developed to realize a scalable, efficient 4-micron laser. A Nd:YAG laser is tuned to 1.3391 microns by temperature-tuning and cavity selection. The addition of diode seeding permits excitation of a specific v = 3 rotational state of HBr. Lasing can potentially occur in three subsequent steps to the ground state, emitting numerous lines in the 4-micron region, which enhances efficiency and spectral coverage. Using up to 25-mJ pump energy, two elements of the possible three-level cascade have been observed. We have observed emission selectivity due to intracavity carbon dioxide and inferred the presence and contributory influence of pure-rotational stimulated emission, which may have importance to the overall behavior of other similar molecular pulsed lasers (and even continuous-wave HX lasers). We present theoretical and experimental results demonstrating the operational principle and utility of this laser system.