ARTICLES: Waveguide CO2/OsO4 laser with a frequency stability of 10-13
A high-pressure waveguide CO2 laser was stabilized using the resonance frequency of saturated absorption due to the A22P(46) transition in the ν3 band of 192OsO4 (28.46 THz). The laser had a preliminary frequency stabilization system based on a transmission resonance of an external Fabry–Perot interferometer, narrowing the emission spectrum to 1 kHz. An external absorption cell was used: it contained OsO4 vapor at a reduced pressure. The frequency instability was measured by comparison with the frequency of a low-pressure CO2/OsO4 laser stabilized using a resonance located at the center of the CO2 P(14) line. The relative instability of the frequencies of the lasers was 10−13(τ−1+2τ0) for values of τ from 1 msec to 400 sec. The long-term stability (flicker limit) of ~10−13 was probably governed by pulling effects arising, in particular, from parasitic reflections in the optical system.