Design of SMMW Laser Resonators with On-Axis Signal and Pump Beam Guiding in a Mirror Ring

A ring resonator design for optically pumped submillimeter wave (SMMW) lasers using the same set of four mirrors (including one focussing mirror) for pump beam and SMMW beam guiding is introduced.The optimum design is discussed on the example of a 2.523 THz methanol laser. It turns out that the focal length of the focussing mirror has to be adapted to the resonator perimeter. Eleven well suited focal length - resonator perimeter ratios, defining eleven standard resonator configurations, can be distinguished.The setup of an experimental laser with the optimized resonator and the experimental setup to measure laser performance are described, and results concerning laser output power, beam quality and efficiency are discussed.This paper is the extended version of the paper presented on the 23rd International Conference in Colchester 1] and continues a former article presented in this journal 2].