Overtone cw chemical HF laser with an extended active medium

The operation on the first overtone transition of the HF(ν) molecule is demonstrated for a cw chemical laser with a three-jet nozzle unit using a nozzle — nozzle — nozzle reagent mixing scheme. The energy, spatial, and spectral characteristics of the laser, as well as the efficiency of conversion of the chemical energy of the pump reaction to the overtone radiation are experimentally estimated. Lasing with an output power of ~1.1 kW and a conversion efficiency of 18 % is obtained in the 1.321 — 1.34 μm wavelength range. The extent of the lasing region is 5.3 cm, which is several times longer than in a laser employing a two-jet nozzle unit with a radial expansion in a nozzle — injector scheme.