The scalable planar waveguide component technology: 40 and 256-channel echele grating demultiplexers

Echelle grating demultiplexers with 40 channels (100 GHz channel spacing) and 256 channels (25 GHz channel spacing) have been fabricated on a silica-on-silicon planar waveguide platform. The optical performance is comparable for both devices, apart from the expected increase in insertion loss for the 256-channel demultiplexer. Adjacent channel crosstalk for both devices is -30 dB or better. The polarization dependent wavelength shift of the output channels is less than 0.01 nm. The echelle grating itself has been designed to reduce intrinsic polarization dependent loss to less than 0.2 dB. The 256-channel demultiplexer including output waveguides occupies a chip approximately 2 × 4 cm in size.