Bragg effect waveguide coupler analysis.

We present an approach to the analysis of a holographically produced grating coupler, in which we separate the coupling problem into independent slab waveguide and diffraction grating problems. Considering the guiding structure as a slab waveguide, we obtain the parameters of the propagating modes of the coupler through conventional analysis. The diffraction efficiency of the grating orders are then calculated by using the thin grating decomposition method (TGD). Utilizing the propagating mode angles of the waveguide and the calculated diffraction efficiencies of the grating, we are able to calculate the radiation loss coefficient and therefore the coupling efficiency of the holographic waveguide coupler.