Research Article

Design of Si₃N₄-TFLN heterogeneous integrated device with phase modulation and frequency doubling: Performance optimization and application prospects

Army Engineering University Shijiazhuang Campus, Shijiazhuang 050003, China

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 9 January 2026
Accepted: 14 February 2026

Abstract

Electro-optic phase modulation is a core technology for signal processing in optical communication and microwave photonics, yet the current multifunctional integrated devices for high-bandwidth phase modulation and efficient frequency doubling suffer from critical bottlenecks including large crosstalk, excessive chip area, bandwidth-voltage trade-off, and single material performance limitations. To address these issues, this study proposes a Si₃N₄-TFLN heterogeneous integrated design scheme by synergizing the low-loss property of silicon nitride and the strong electro-optic effect of thin-film lithium niobate. A Dual-Drive Mach-Zehnder Modulator (DD-MZM) and a racetrack Micro-Ring Resonator (MRR) with high quality-factor and large Free Spectral Range (FSR) are cascaded to realize the monolithic integration of high-precision phase modulation and microwave signal frequency doubling. Co-simulation results show that the designed device achieves an electro-optic modulation bandwidth of 72 GHz and a half-wave voltage-length product of 2.8 V · cm, which well reconciles the bandwidth-voltage trade-off. The device exhibits a frequency-doubling efficiency of 15%, 30.4% higher than that of the single TFLN-based MRR. The cascaded coupling structure suppresses the functional crosstalk to −38 dB, and the total chip layout area is only 3.648 mm², over 60% smaller than that of the existing similar devices. This work provides a high-performance on-chip solution for high-density integrated systems in optical communication, microwave photonics, and quantum information processing.