TRANSVERSE MODES OF AN OPTICAL RESONATOR WITH GAUSSIAN MIRRORS: A THEORETICAL STUDY

Analytical methods are presented for transverse mode analysis of a laser resonator having spherical mirrors with a Gaussian reflectivity profile. The modes of such resonators have a form similar to that of the conventional Gaussian modes, but it is necessary to define a secondary beam parameter in order to meet the self-consistency requirement for resonator modes. The methods presented are applied to a simple symmetrical resonator and a more realistic regenerative amplifier cavity. Stability of both the conventional complex beam parameter and the secondary beam parameter are discussed. It is predicted mathematically that small perturbations in the secondary beam parameter will cause the intensity profile of the higher order modes to evolve into that of the fundamental mode. Mode losses and discrimination are also discussed. It is found that effective transverse mode discrimination requires high losses in the fundamental mode.