Experimental demonstration of Generalized Phase Contrast based Gaussian beam-shaper.

We report the first experimental demonstration of Gaussian beam-shaping based on the Generalized Phase Contrast (GPC) approach. We show that, when using a dynamic spatial light modulator (SLM), this approach can rapidly generate arbitrarily shaped beams. Moreover, we demonstrate that low-cost binary-phase optics fabricated using photolithography and chemical etching techniques can replace the SLM in static and high power beam shaping applications. The design parameters for the binary-phase elements of the module are chosen according to the results of our previously conducted analysis and numerical demonstrations [Opt. Express 15, 11971 (2007)]. Beams with a variety of cross-sections such as circular, rectangular and square, with near flat-top intensity distributions are demonstrated. GPC-based beam shaping is inherently speckle-free and the shaped beams maintain a flat output phase. The non-absorbing components used in this beam-shaping approach have a high-damage-threshold and are thus ideally suited for high power applications.