Abstract

Unstable-cavity lasers have attracted much attention because of the interesting properties of their eigenmodes including non-orthogonality and fractal character.¹ Non-orthogonality has profound consequences for the quantum- limited laser linewidth Δv leading to its enhancement by the so-called excess noise factor K. This factor depends on the eigenmode field distribution, which in turn depends on cavity geometry. However, only lasers with square and circular intra-cavity apertures have previously been the subject of detailed investigation.² The full extent to which 2D transverse geometry influences K has thus remained an open question. We report the first theoretical and experimental investigations of fi-factors in lasers with truly 2D aperturing.

© 1999 Optical Society of America