Modulation of gas laser radiation by an alternating magnetic field

A semiclassical vector theory of a Zeeman gas laser is used in an analysis of the amplitude and frequency modulation of linearly polarized radiation. Arbitrary detuning of the emission frequency relative to the center of the laser transition is discussed. It is assumed that the active medium is modulated by an alternating magnetic field. The steepness of the dispersion characteristic and the depth of modulation of the intensity at the second harmonic of the modulation frequency are both functions of the parameters of the active medium, resonator, and magnetic field amplitude. A qualitative agreement is reported between the experimental results obtained for an He–Ne laser (λ = 0.63 μ) and the theoretical calculations. The results may be useful in studies of fluctuations of gas-laser radiation due to the application of alternating magnetic fields; they may also be applied in the design of some frequency stabilization systems and in laserspectroscopic determinations of the constants of the active atoms under stimulated emission conditions.