Research on High-Performance and Low-Loss Thin-Film Lithium Niobate Electro-Optic Modulatorser

In the future development of optical communication systems, high-speed modulators are critically important, requiring high modulation efficiency, low loss, and compact size. Thin-film lithium niobate modulators typically achieve low driving voltage by employing narrow electrode gaps or elongated Mach-Zehnder interferometer arms. However, these designs often increase microwave losses, thereby limiting the modulator's bandwidth performance. To address this issue, this study proposes an asymmetric arrangement of optical waveguides relative to the electrodes, along with the introduction of a dielectric buffer layer beneath the electrodes and a high-permittivity cladding layer above the waveguides. This approach effectively mitigates the trade-offs between these performance metrics. In this paper, an electro-optical modulator with an electro-optical modulation bandwidth of 152 GHz, an optical loss of less than 2.2 dB/m and a single-arm modulation efficiency of 3.55 Vꞏcm is realised by finite element analysis software.