BRAGG-DIFFRACTION OF SPATIALLY PARTIALLY COHERENT FIELDS

A spatially partially coherent two-dimensional beamlike wave field wit h arbitrary distributions of the optical intensity and complex degree of spatial coherence is assumed incident on a diffraction grating with an arbitrary periodic permittivity modulation. Rigorous electromagnet ic: diffraction theory of gratings is used, together with the coherent -mode representation of partially coherent fields, to calculate near-f ield and far-zone distributions of the zeroth-order beam and the Bragg -diffracted beam. A volume grating with significant Bragg selectivity is shown to increase the spatial coherence of the diffracted beam, but the diffraction efficiency is simultaneously reduced. (C) 1997 Optica l Society of America.