Enhancing the field of view of a distributed-cavity laser incorporating cat-eye optics by compensating the field-curvature

Abstract

The influence of field curvature (FC) on a distributed-cavity laser incorporating cat-eye optics was theoretically and experimentally investigated. We found that the FC can defocus the cat-eye and seriously limit its field of view (FoV), since the cavity stability region becomes very narrow at long working distances of several meters. Three improved cat-eye designs are demonstrated, in which the FC-induced defocusing was compensated by choosing off-the-shelf components with appropriate parameters or by using a customized aspheric lens. With these new designs, a distributed-cavity diode-end-pumped Nd:YVO4 laser was capable of operating efficiently within a large receiver FoV of ±20°, which was an order of magnitude larger than that achieved prior to optimization (using a traditional cat-eye design), at a long working distance of 5 m. The effectiveness and robustness of these new designs pave the way for alignment-free lasers with long-distributed-cavities, which are essential for resonant laser charging applications.