Investigation of a CW HCN laser discharge, optimization of parameters and scaling laws: Construction and applications

Means of increasing the output power per unit volume for discharge excited mixtures of nitrogen, methane and helium in a CW HCN laser were investigated. It was found that maximum power increases with decreasing tube diameter up to a limit imposed by increasing diffraction losses. It was also found that the pyrex discharge tube may be used as a dielectric waveguide thereby reducing these losses and increasing the power to volume ratio of the laser. Scaling laws for CW waveguide HCN lasers were deduced from these results, and a 5 cm diameter laser with a 2 m long discharge and an output power of 100 mW was constructed. Technical problems relating to reliability and power stability were solved. The modes of the 100 mW waveguide laser were studied using a liquid crystal camera. Experimental methods were developed for measuring the electron density of the laser plasma, the gain coefficient, and the cavity losses. These methods could be applied to other submillimeter lasers.