GENERALIZATION OF THE BOUNDARY DIFFRACTION METHOD FOR VOLUME GRATINGS

The boundary diffraction method (BDM) is an approximate method that pe rmits the derivation of analytic solutions for the output beams, both forward and backward propagating, that arise from the fundamental natu re of holographic gratings. The method is based on the assumption that the volume scatter inside the grating can be supplemented by boundary diffraction coefficients. The boundary diffraction method is used for analysis of thick transmission geometry gratings in a unified way tha t deals with both the slanted and the unslanted cases. During the anal ysis, evidence emerges for the superiority of the first-order two-wave beta-value method over the Kogelnik k-vector closure method. The BDM is then further generalized to the case of a volume transmission grati ng, index matched to its surroundings, and replayed normally on-Bragg, i.e., satisfying the Bragg condition for normal incidence. The analyt ic equations derived are compared with results calculated with the rig orous coupled-wave method.