Experimental Results on Gas-Lens Effects in (He-Ne)/CH/sub 4/ Lasers (/spl lambda/= 3.39 /spl mu/m)

Design criteria have been established allowing the cancellation of spurious frequency offsets induced by gas-lens effects in He-Ne lasers stabilized by saturated absorption in an intra-cavity absorber cell. They have been checked experimentally using a specially designed laser. Good agreement is generally found between theory and experiment in spite of unexplained effects at low modulation amplitudes. Also observed in this special laser is the output effect, i.e. the frequency change which occurs when the photodetector used for servo-control is at one end or the other end of the resonator.