Spatial Combining of Laser-Diode Beams for Pumping an NPRO

A free-space optical beam combiner now undergoing development makes it possible to use the outputs of multiple multimode laser diodes to pump a neodymium-doped yttrium aluminum garnet (Nd:YAG) non-planar ring oscillator (NPRO) laser while ensuring that the laser operates at only a single desired frequency. This optical beam combiner serves the same purpose as does the one described in “Diffractive Combiner of Single-Mode Pump Laser-Diode Beams” (NPO-42411), NASA Tech Briefs, Vol. 31, No. 5 (May 2007), page 16a. Although the principles of design and operation of the present and prior beam combiners are not identical, they are so closely related that it is necessary to devote the next four paragraphs to reiteration of a substantial portion of the cited prior article in order to give meaning to a description of the present beam combiner.