Design and fabrication of a low crosstalk SiO/sub 2//Si array waveguide gratings

The origin of random phase errors form the crosstalk induced by the corresponding fabrication processing parameters' based on silicon in AWG (array waveguide grating) is analyzed by considering waveguide structure and refractive index distribution uniformity. Several analytical formulas for crosstalk level estimation are given. With them a 40 channel AWG de-multiplexer is designed and fabricated. The experiment shows that the crosstalk level between non-adjacent channels is as low as -45dB, with the random change in waveguide geometric structure in silicon substrate is less than 0.5 mum, the average refractive index deviation of core layer and cladding layer is less than 2 times 10^-4 and 6 times 10^-4