Description:
Frequency stabilization of an optically-pumped CH3OH laser oscillating in the 469 µm line to a phase-locked 71 GHz reference was investigated. The CO2 pump laser was offset-locked to the 4.3 µm-fluorescence stabilized CO2 laser. A frequency stability σy(τ) of 2×10-11 in terms of the square root of the Allan variance was obtained at 469 µm, where τ is the averaging time. The stability is discussed in conjunction with the dispersion effect of the oscillation frequency due to variation of the pump frequency and also with the oscillation frequency shift due to variation of the pump power.