Internal modulation of gas laser radiation by acoustic surface waves

A method for internal modulation of gas lasers by acoustic surface waves is analyzed theoretically. It is shown that excitation of a traveling amplitude-modulated surface wave in one of the resonator mirrors may, under certain conditions, modulate the laser radiation at the frequency of modulation of the acoustic wave amplitude. The modulation of the laser radiation is due to the periodic variation of the losses in the resonator. The depth of the power modulation depends on the amplitude, frequency, and depth of modulation of the acoustic wave. Experiments are reported in which He–Ne laser radiation (λ = 0.63 μ) was modulated between 100 Hz and 10 kHz by exciting a traveling amplitude-modulated acoustic surface wave of 10 MHz frequency in a resonator mirror. The relationships describing the modulation process were in good agreement with the theory.