Resonant coupling between bulk waves and guided modes in a dielectric   slab with a thick holographic grating
  What we believe to be a new type of resonant coupling of an incident bulk wave into guided modes of a slab with a thick holographic grating is shown to occur in the presence of strong frequency detunings of the Bragg condition. This happens through the reflection of the strongly noneigen +1 diffracted order with the slab-grating boundaries, the resultant reflected waves forming a guided slab mode. Rigorous coupled-wave analysis is used for the numerical analysis of the predicted resonant effects. Possible applications include enhanced options for the design of multiplexing and demultiplexing systems, optical signal-processing devices, optical sensors, and measurement techniques. 
D. R. Mason, S. J. Goodman, D. K. Gramotnev and T. A. Nieminen