Frequency stabilization of 633-nm He-Ne laser by using frequency modulation spectroscopy of I-127(2) enhanced by an external optical cavity

The oscillation line from a two-mode stabilized inner-mirror-type 633-nm He -Ne laser was locked to the iodine saturated absorption line. FM spectrosco py was used to detect the saturated absorption signal. An iodine cell was p laced within the ring cavity to multiply the excited light. When the oscill ation line on the red side (long-wavelength side) of the two-mode stabilize d laser was locked to the 6-3 band P(33) transition a-component of I-127(2) , the degree of frequency stabilization measured from the Allan variance si gma(2, tau) was 2.3 x 10(-11) x tau(-1/2) On either the red or blue side. U nder this condition, the nonmodulated optical power on the blue side was 1. 3 mW. In addition, the dependence of the frequency shift of the P(33) trans ition a-component on iodine vapor pressure and the frequency separations of oscillations for a to j components were measured. (C) 2000 Scripta Technic a, Electron Comm Jpn Pt 2, 83(3): 1-9, 2000.