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