Beam splitting, combining, and cross coupling through multiple superimposed volume-index gratings

We investigate the diffraction properties of multiple-superimposed index gr atings from a vector synthetic viewpoint using coupled wave analysis with B ragg and non-Bragg readout. The vector synthetic gratings consist of two vo lume-index gratings with different grating wave vectors, which can be obtai ned in photorefractive materials, in optical fibers or in Bragg cells with two driving acoustic waves. This structure can realize beam splitting, beam combining, and beam cross coupling, etc. Analytic expressions for the diff raction efficiency as well as the amplitude of the waves involved are obtai ned. The results are presented and discussed. (C) 2001 Elsevier Science Ltd . All rights reserved.