High-speed polarization control in integrated silicon photonics

The proliferation of inverse design techniques in photonics integrated circuits (PICs) has expanded the scope of applications for the adjoint method, particularly in developing ultra-compact and efficient on-chip integrated components. Here, we demonstrate the design and implementation of advanced polarization control systems with high-speed performance. The design employed an inverse-designed ultra-compact polarization beam rotator-splitter (PBRS) with a high-speed PN junction phase shifter in a silicon photonics platform. The inverse designed PBRS is ultra-compact (17 μm) with an insertion loss < 1.0 dB in the C-Band (<0.5 dB at 1550 nm), and exhibits an extinction ratio > 20 dB. Its combination with a plasma dispersion-based modulator integrated into a Mach-Zehnder interferometer, enables rapid changes in output polarization states. The proposed polarization control optical circuit's performance is demonstrated at 32 Gbit/s at 1550 nm wavelength, showcasing the potential for advanced high-speed polarization control applications.