Stable 1.25-W CW Methanol Laser

Far-infrared (FIR) laser operating at 119-micrometer-wavelength transition of methanol achieves very low drift in frequency. Continuous-wave (CW) FIR output is 1.25 W when laser pumped by 125-W commercial CO2 laser. Rate of drift of output frequency less than plus or minus 100 kHz per hour because laser designed to have low thermal-expansion coefficients and because temperatures of input and output couplers held within 0.1 degree C of fixed values.