Phase-polarization methods for control of the frequency spectrum of laser radiation

A theoretical analysis is made of the methods for control of the frequency spectrum of laser radiation on the basis of conversion of the frequency dependence of the refractive index of the active medium into the frequency dependence of the losses. The conversion is made by rotation of the plane of polarization (Faraday effect) or by phase anisotropy established in the active medium. The formalism of the Jones matrices is used to obtain the dependence of the losses on the angle of rotation of the plane of polarization or on the degree of phase anisotropy in some specific cases. A calculation is reported of the frequency dependence of the losses within the Voigt gain profile with specific parameters. Experimental results obtained for He–Ne lasers emitting at λ=3.39 and 0.63μ, support the usefulness of these methods in frequency selection and narrowing of the emission spectrum.