Thin-film lithium niobate Polarization-Independent Modulators for Mode and Polarization Multiplexing

We demonstrated a high-order mode modulator based on thin-film lithium niobate (TFLN). By introducing a mode converter and a polarization splitter-rotator (PSR), the modulator can achieve dual-mode modulation. Additionally, we designed a periodic capacitively loaded traveling-wave electrode on TFLN to enhance modulation efficiency and bandwidth. The modulator exhibits a polarization extinction ratio greater than 20 dB at a wavelength of 1550 nm, a modulation efficiency of V π L TE 0 =2.541V⋅cm and V π L TM 0 =2.570V⋅cm, and a 3 dB bandwidth exceeding 60 GHz. This not only meets the requirements for polarization-independent modulators but also supports on-chip multimode applications such as mode and polarization multiplexing.