Superimposed Holographic Gratings In Single-mode Planar Optical Waveguides For Wavelength Demultiplexing Applications.

Abstract

The idea of using superimposed holographic gratings to achieve high performance optical interconnections and wavelength demultiplexing structures has recently emerged [ 1-21. We present for the first time a coupled mode analysis of superimposed holographic transmission gratings in single-mode planar optical waveguides. We show that coupling between gratings occurs and affects diffraction efficiencies and wavelength and angular selectivities. In addition, polarization of the input wave, angular and spectral separation of the output channels and relative strengths of the gratings have to be taken into account in device design and analysis. Nevertheless, very good angular and wavelength channel separation (< 0.2 and < 20A), low crosstalk (-20dB) and high fanout density are shown to be achievable in properly designed devices. (I] holographic gratings and substratc wave propagation. Appl. Opr., vol. 3 1. pp. 236-249, 1992.