Waveguide CW 118.6-micron H2O laser

This paper reports results of an experimental study of a CW 118.6-micron H2O waveguide laser. The laser cavity is a 3 cm-inner diameter, 3.2 m-long Pyrex tube, with plane reflectors against its ends, one of them being a copper mesh coupler. The active medium is an H2O:H2 gas mixture. Successive optimizations lead to a reliable output power of 50 mW, for the EH11 mode. The power density is the highest ever reported, and the stability is such that the power drifts by less than 2% per hour. This laser is competitive with the optically pumped 118.8-micron CH3OH laser.