Spherical mirror resonators and optical mode selection

approved (Major professo This is a review paper based on recent literature in the areas of spherical mirror resonators and optical mode selection. The Fabry -Perot interferometer with spherical mirrors has been widely used as a laser resonator. The modes of oscillation, diffraction losses and resonance condition are determined for the confocal resonator, i. e, a resonator with mirror spacing equal to the common radius of curvature of the mirrors. Resonators with nonconfocal spacing and mirrors of different curvature are described in terms of an equivalent confocal resonator. It is shown that any spherical mirror resonator may be characterized as high loss or low loss according to the geometry of the resonator. Lasers using spherical mirror resonators will oscillate in several modes simultaneously, because of the interaction of the broad emission line of the laser active medium and the closely spaced mode resonances. For many applications a single frequency output is desirable, and methods must be employed to suppress unwanted oscillations. Unwanted modes may be suppressed by placing absorbing materials within the resonator and by adding devices to the resonator which act as bandpass filters. SPHERICAL MIRROR RESONATORS AND OPTICAL MODE SELECTION