Polarization compensators in silicon-on-insulator reflectiveinterconnects

摘要

We report on our recent progress in polarization control and polarization compensator designs in SOI-based planar reflective gratings for a range of silicon core thicknesses of 0.1 urn to 10 μm. The dispersion property of the silicon slab, without a compensator region, was found to limit the applicability of SOI gratings for achieving the polarization-insensitive performance of wavelength division multiplexing systems based on planar gratings. We have found that in coarse wavelength division multiplexing systems, the birefringence of the uncompensated slab becomes impractical at core thicknesses below 1.7 μm. Our findings clearly show that shallow etched polarization compensators can effectively eliminate polarization dependence only in thick-core gratings and only in applications requiring free spectral ranges (FSRs) of no more than 80 nm. In silicon cores with thicknesses of less than 1.0 μm, the significantly different value of linear dispersion strength for the two polarization states make traditional compensator designs ineffective, since only the central wavelength can be fully compensated. We used our findings to construct a procedure for building compensators with a flat polarization response over wide FSRs (> 80 nm). The results of our study were applied to the design of a polarization compensator in an 18-channel multiplexer for use in coarse wavelength division multiplexing. Our simulation results show that a careful selection of the silicon core thicknesses in the slab and compensator regions is essential for achieving low-cross talk and low insertion loss devices. The application of thin core planar silicon gratings to building silicon interconnects is discussed.