SIMPLE METHOD OF FABRICATING POLARIZATION-INSENSITIVE AND VERY-LOW CROSSTALK AWG GRATING DEVICES

A simple method of fabricating polarisation insensitive and very low c rosstalk dense-WDM devices has been developed. The matching of the the rmal coefficient of expansion (TCE) of the overcladding layer to the s ilicon substrate, for a 16 channel arrayed-waveguide demultiplexer, re sulted in very low polarisation sensitivity (0.03nm). The TCE of the u ndercladding and the core layers, on the other hand, were found to hav e negligible effect on the polarisation sensitivity. PECVD was used fo r depositing all the oxide layers.