Dynamics of a class-B bidirectional ring laser with a nonreciprocal cavity: model with two gain profiles

The results are given of an analysis of the stability of the travelling-wave regime in a ring laser model that takes account of the real structure of the gain profile of neodymium-doped yttrium aluminate garnet. A travelling-wave steady state of the system is found by considering such system parameters as the linear coupling of counterpropagating waves at microinhomogeneities of optical components, the amplitude and phase nonreciprocities of the cavity, and the detuning of the lasing frequency from the centres of both gain profiles. An explanation is given of the change in the resonance peaks in the spectrum of fluctuations of the intensity of the radiation emitted by a solid-state ring laser due to reversal of the sign of the phase nonreciprocity, observed experimentally earlier.