Thermostabilization of Methane Optical Frequency Standard

We report investigation of frequency response of the He-Ne laser stabilized over methane line on temperature fluctuations. Stabilization technic is based on saturated dispersion resonance registration in two-mode laser with orthogonal polarizations. Anisotropic elements of the laser cavity are sensitive to temperature fluctuations that lead to laser frequency drift for averaging time more than 10 s. We developed temperature stabilization system with 10 mK stability in the range from 20 to 45 degrees C. That makes possible to shift temperature working point and measure temperature coefficient of the stabilized frequency (TCF) for this type of optical standard.