Polarisation of a neodymium laser with a passive switch based on a Cr4+:YAG crystal

An experimental investigation is reported of the state of polarisation of the radiation generated in a neodymium laser with a passive switch based on a Cr⁴⁺:YAG crystal. A description is provided of the observed dependences. This description is based on the assumption that at each moment of the evolution of lasing the state of polarisation of the laser radiation represents an eigenstate corresponding to the lowest radiation losses. This state is governed by the relative orientations of the switch and of an intracavity partial polariser, as well as by the radiation energy density in the switch. The calculated results are shown to fit the experimental data.