Accession Number : AD0460878
Title : Unstable Optical Resonators for Laser Applications
Descriptive Note : Internal memo.
Corporate Author : STANFORD UNIV CA MICROWAVE LAB
Personal Author(s) : Siegman, A E
Report Date : Sep 1964
Pagination or Media Count : 47
Abstract : A simple geometrical analysis was developed which describes the lowest-order transverse mode in an arbitrary unstable optical resonator of large Fresnel number. The lowest mode is assumed to consist of two oppositely traveling spherical waves which uniformly illuminate the two end mirrors. The centers of curvature of these two waves (which are not in general the mirror centers of curvature) are found by requiring that each center be the image of the other upon reflection from the appropriate spherical end mirror. The resonator losses, found from simple geometrical considerations, are given by simple analytical expressions and are entirely independent of the mirror sizes. The equi-loss contours on the usual mode chart are hyperbolae. The present results agree well with more exact results calculated by Fox and Li for the unstable case, and with experimental results on a ruby laser having a divergent spherical surface ground directly onto the ruby rod. Unstable resonators of this type appear potentially useful for transverse mode control and for diffraction output coupling.
Descriptors : *CAVITY RESONATORS , *LASER COMPONENTS , MIRRORS , STABILITY , DIFFRACTION , SPHERICAL WAVES , RUBY LASERS , CURVED PROFILES , FRESNEL INTEGRALS
Subject Categories : Lasers and Masers
Distribution Statement : APPROVED FOR PUBLIC RELEASE