Simulation of gain anisotropy induced by linearly polarised pump radiation in a bipolar Nd : YAG laser

A model of a bipolar solid-state Nd : YAG laser is proposed, which takes into account the real orientation of the absorbing and emitting dipoles of active Nd³⁺ centres in the unit cell of yttrium aluminium garnet. The model describes the experimentally observed effect of gain anisotropy induced by linearly polarised pump radiation and predicts a new form of instability caused by the presence of two competing pump channels, which have not been considered previously in the literature.