Holographic focusing gratings on the surfaces of optical waveguides

An account is given of a simple holographic system for the formation of diffraction gratings designed to couple out radiation from a waveguide and to focus it in air. Relationships that help to avoid astigmatic aberrations in the course of grating formation are given. Experimental results are reported for a structure that focuses the radiation coupled out of a waveguide, where this radiation has a plane front, to a symmetric spot 6 μm in diameter.