Spectral characteristics of a single-frequency argon laser with an absorbing film

A study was made of the dependence of the output power on the frequency detuning of a single-frequency Ar⁺ laser. The study was carried out in a wide range of longitudinal magnetic fields. Single-frequency emission was achieved by the use of a film selector and the frequency was tuned by altering the distance between the film and the nearest resonator mirror. The highest coefficient of conversion of single-mode to single-frequency emission was ~90%. The dependences obtained were used to stabilize the frequency at the center of the spectral line by automatic adjustment of the distance between the film and the nearest resonator mirror.