High-contrast power resonances in an He–Ne/127I2 laser with a large effective absorption length

An analysis is made of the conditions for obtaining high-contrast resonances in a weakly saturable absorber. A description is given of an experiment in which high-contrast power resonances were established in an He–Ne/¹²⁷I₂ laser. An optical delay line is used as an internal absorption cell for the purpose of increasing the effective absorption length. An analysis is made of the spectrum of the hyperfine structure of the absorption in iodine in this laser. The stability of the laser when locked to one of these resonances is determined.