Silicon photonic circuit with polarization diversity.

We devised a silicon photonic circuit with polarization diversity that consists of polarization splitters and polarization rotators. The splitter is based on a simple directional coupler and the rotator has an off-axis double-core structure. Both devices can be made by using planar fabrication technology and require no complex proceses for the fabrication of three-dimensional structures. We fabricated a polarization-independent wavelength filter based on Si wire waveguides as an application of the polarization diversity. The filter consists of the polarization splitters, the rotators, and a ring resonator. The polarization-dependent loss of the filter is about 1 dB. A 10-Gbps data transmission with scrambled polarization is demonstrated.