High-performance thin-film lithium niobate modulator with periodic capacitively loaded traveling-wave electrodes

Thin - film lithium niobate (TFLN) electro - optic modulators possess characteristics such as large electro - optic bandwidths, high - power handling capabilities, low transmission losses, and high extinction ratios. To further enhance the performance, this paper conducts theoretical analyses and modeling simulations. By adopting periodic T - shaped microstructures and silicon under - cut etching technology, it reduces microwave losses and achieves velocity matching. In combination with a sunken - electrode structure, an electro - optic modulator with a half - wave voltage - length product of 1.86 V·cm and a 3 - dB electro - optic bandwidth exceeding 60 GHz is realized. This modulator features a large bandwidth at a low driving voltage, providing valuable guidance for the design of TFLN electro - optic modulators with micro-structured electrodes.