Mode discrimination in a negative branch confocal unstable resonator with a round aperture and spherical mirrors was studied by numerically computing the lowest loss modes and their losses. Selected intensity and phase profiles of the modes are shown. The mode discrimination ratio (DR), the ratio of the fractional feedback powers of the lowest loss mode to the second lowest loss mode, is simply the geometric resonator magnification squared. To study the effects of aberrations on the mode discrimination, an astigmatic and a random phase distortion were introduced in the resonator. In the range of parameters where the far field Strehl ratio exceeded 0.4, the DR remained significantly greater than unity indicating that the resonator maintains good mode discrimination in the presence of these aberrations.

Date Published: 1 June 1990
PDF: 12 pages
Proc. SPIE 1224, Optical Resonators, (1 June 1990); doi: 10.1117/12.18430

Published in SPIE Proceedings Vol. 1224:
Optical Resonators
Dale A. Holmes, Editor(s)