400-Channel 25-GHz-spacing SOI-based planar waveguide demultiplexer employing a concave grating across C-and L-bands

The 400-channel 25-GHz-spacing SOI-based planar waveguide demultiplexer employing a concave grating across C- and L-bands is proposed in this paper. For the high polarization dependence, the waveguides are designed for supporting the TE mode only. To reduce the spherical aberration of the concave grating, the values of the maximum half divergent angle of the light source and minimum effective half width of the fundamental mode of the ridge waveguide are determined. We use a design example to show the spectral characteristics of the proposed design. Simulation results show that the proposed design provides better spectral characteristics and smaller die size.