Electro‐optic modulators based on thin‐film lithium niobate (TFLN) are pivotal components in microwave photonic systems. A sunken electrode structure is proposed in this work to improve the device performance. Systematic simulations of the modulator’s modulation efficiency and RF characteristics were conducted using the finite element method. Simulation results demonstrate a half‐wave voltage‐length product ( V π · L ) of 2.11 V·cm, an optical absorption loss as low as 0.03 dB/cm, and a modulation bandwidth of over 100 GHz. Experimental characterization of the fabricated device revealed a V π · L of 2.66 V·cm and a modulation bandwidth that significantly surpasses 40 GHz. A comparative analysis with conventional traveling‐wave electrode structures confirms that the proposed sunken electrode structure significantly reduces optical absorption loss while preserving excellent modulation efficiency and high‐frequency performance. This provides a new approach for subsequent related research and device design.
Hao et al. (2026) studied this question.