Full-band high-speed arbitrary polarization manipulation leveraged by anisotropic electro-optic modulation in thin-film lithium niobate

Polarization controller (PC) serves as a critical component for manipulating the polarization state of light and holds great significance in both classical and quantum communication systems. Anisotropic electro-optic (EO) modulation in thin-film lithium niobate provides a new avenue for realizing high-speed PCs. This paper presents a high-performance on-chip PC with a simple architecture, assembled from linear tapers, Y-branch splitters, and EO phase shifters. The proposed PC has an ultra-broad working bandwidth that covers the entire optical communication spectrum. It enables arbitrary polarization manipulation. Endless polarization generation is realized at typical wavelengths of 1550 and 1310 nm, while exhibiting a record-high dynamic polarization extinction ratio >43 dB. High-speed random four-polarization encoding for quantum key distribution at a switching speed of 20 MHz is demonstrated. Enabling polarization manipulation with high speed, high PER and broad bandwidth, the PC offers huge potential for performance enhancement in optical systems.