Mode study, beam characteristics and output power of a CW 377μm HCN waveguide laser

Abstract

Describes the first continuous submillimetre waveguide laser operating on the 337 mu m HCN line, and presents the results of the first comprehensive experimental study of its low-loss modes. The laser cavity is a 5 cm diameter, 2.4 m long Pyrex tube with plane reflectors (one of them is a metal mesh) against its ends. Eight waveguide modes were identified. Intensity distributions in the beam cross section and mode polarization were studied. The results agree with theoretical predictions for dielectric waveguide modes. The propagation of the EH₁₁ mode in free space was also studied. The beam propagates as a gaussian beam at moderate and large distances from the mesh coupler. The maximum output power of the laser is of the order of 100 mW, representing the highest output power per unit volume so far reported for a continuous HCN laser.