Design of a Polarization-Insensitive Echelle Grating Demultiplexer Based on Silicon Nanophotonic Wires

A polarization-insensitive design of an echelle grating (or etched diffraction grating) demultiplexer based on silicon nanowires is proposed in the present letter, by introducing a polarization compensation area in its free propagation region. The polarization-dependent wavelength shift of the present device has been compensated at the whole spectral range. For a design with nine channels and 10-nm channel spacing, when the wavelength shift at the central channel 1550 nm is completely compensated, the wavelength shifts of the two edge channels are only 0.14 and 0.15 nm, which are acceptable.