Abstract:
The results are given of theoretical and experimental investigations of frequency-modulation saturated-absorption and saturated-dispersion resonances in a linear He–Ne laser employing an intracavity methane absorption cell. The ultimate sensitivity of the method of frequency-modulation spectroscopy of an intracavity absorbing gas was shown to be 10–11cm–1·Hz1/2. Studies were made of the stability and of the frequency shifts of a linear He–Ne/CH4 laser stabilized by frequency-modulation resonances of the saturated dispersion and saturated absorption. A frequency stability of 8×10–15 for an averaging time of 1 sec and a frequency reproducibility of 10–13 were obtained.