SPATIAL CHARACTERISTICS OF A LASER-OSCILLATOR FORMED BY OPTICALLY-WRITTEN HOLOGRAPHIC GAIN-GRATING

We investigate the spatial characteristics of a Nd: YAG unidirectional ring resonator formed by an adaptive holographic gain-grating. Diffraction-limited spatial output is demonstrated from the resonator even with very strong intracavity phase distortion. We also show that, despite good intracavity phase compensation and good spatial output quality, the output mode size is not generally the same as the self-intersecting input beam that forms the gain hologram. A simplified theory, to account approximately for a spatially-Gaussian input beam, gives qualitative agreement with the key features observed in the experimental resonator.