A Compact Hybrid Plasmonic Polarization Rotator for Silicon-Based Slot Waveguides

A compact polarization rotator (PR) for silicon-based slot waveguides is proposed, where a metal strip of aluminum (Al) is embedded in its upper-claddings. With the features of asymmetric hybrid plasmonic waveguide induced by the metal strip, an optimal optical axis rotation angle of 45° is realized, leading to high polarization conversion efficiency (PCE). The numerical results show that a PR of 11.6 μm in length at the wavelength of 1.55 μm is achieved with the PCE and insertion loss of 97.6% and 0.86 dB for TM-to-TE conversion, respectively. In addition, fabrication tolerances to the structural parameters are investigated and field evolution along the propagation distance through the PR is demonstrated.