Transverse Modes of Microchip Solid State Lasers

We present a model for an end pumped microchip solid state laser with plane-parallel cavity mirrors. Our model has a transversely varying gain and gives the laser threshold, output intensity, frequency and the transverse mode profiles in terms of the cavity detuning, cavity losses and other relevant parameters. We have also adapted the model to derive the pump threshold for simultaneous operation of two transverse models. We find that these lasers almost always operate on the fundamental mode and only for broad pump beams and high pump powers can higher order modes be excited.