Diffraction limited CW optically pumped lasers

The far infrared spectral characteristics of inductive metal mesh dielectric hybrid mirrors were investigated. From experimental and theoretical studies, the mirrors were found to exhibit etalon effects due to the finite Si substrate thickness and to have two separate diffraction conditions. With grid spacing g and substrate index of refraction n, for 1/n less than g/lambda less than unity the mirrors diffract in transmission, while for g/lambda greater than 1 the mirrors diffract both in transmission and reflection. Using both inductive and capacitive mesh mirrors, EH(11) outputs have been obtained at the milliwatt level in the range 70 microns to 1.2 mm. Powers in excess of 10 mW were obtained from CH3OH at 96 and 118 microns, HCOOH at 393 microns, CH3I at 447 microns, and CH3F at 496 microns.