Abstract

In this paper we offer rigorous substantiation and derivation of a class B laser model with orthogonal elliptically-polarized modes, provide a theoretical analysis of the laser dynamics and compare the results with experimental data of the fiber laser. It is assumed that the laser medium is an ensemble of active centers randomly oriented in space. Off-diagonal matrix elements of the dipole moment d₂₁ = d₂₂ ⁼ d are linearly polarized in the cavity cross-section plane. The evolution of the active centers depends on the pump wave polarization [1]. The fiber host which contains active centers is weakly anisotropic; its permeability is described by the hermitian dielectric constant tensor (e_jk= e_kj*). The eigenmodes of a cavity, containing such a medium, arc elliptically polarized. Interaction of polarized radiation with the ensemble of randomly oriented molecules results in the nonuniformity of the angular inversion distribution in the plane perpendicular to the cavity axis; this distribution is taken into account by introducing the angular harmonics: N = No + 2N_ccos2Y + 2N_ssin2Y + … . Psi is the azimuth in the cross section plane. Each angular harmonic N_i (i=o,c,s) consists of a spatially homogeneous part and a large-scale spatial harmonic induced by the joint action of the cavity modes: N_i = N_i0+ 2N_i12 cos(k₁′ − k₂′)z.

© 1996 IEEE