J. Eur. Opt. Society-Rapid Publ. 2026, 22, 16 Ó The Author( s), published by EDP Sciences, 2026 https:// doi. org / 10.1051 / jeos / 2026013 Available online at: https:// jeos. edpsciences. org
Journal of the European Optical Society-Rapid Publications
Recent Advances on Optics and Photonics 2026 Guest editors: Manuel Filipe P. C. M. Costa, Rogerio Nogueira and Alessandro Fantoni
Research Article
Design of Si 3 N 4-TFLN heterogeneous integrated device with phase modulation and frequency doubling: Performance optimization and application prospects
Ting An
, Limin Liu *, Guizhou Lv, and Yunfeng Jiang Army Engineering University Shijiazhuang Campus, Shijiazhuang 050003, China
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 Si 3 N 4-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 mm 2, 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.
Keywords: Dual-drive Mach-Zehnder modulator( DD-MZM), Frequency doubling, Lithium niobate( LN), Micro-ring resonator( MRR), Phase modulation, Frequency doubling.
1 Introduction
For application scenarios such as optical communications [ 1 – 3 ], fiber-optic sensing [ 4, 5 ], and microwave photonics [ 6 – 9 ], the efficiency and precision of electro-optic phase modulation technologies have become key drivers for advancing system performance. Silicon-based electro-optic phase modulators [ 10, 11 ], leveraging their compatibility with semiconductor processes, low power consumption, and high integration potential, have emerged as a promising technology in the field of short-range optical interconnections. However, constrained by intrinsic material properties such as low electro-optic coefficients and high losses, siliconbased devices still face bottlenecks in ultra-high-speed, longdistance, or high-power scenarios. In contrast, lithium niobate( LN) phase modulators, with their comprehensive advantages including exceptional frequency bandwidth, fast response speed, low insertion loss, high signal-to-noise ratio, low half-wave voltage, and excellent stability, have become
* Corresponding author: liulimin0807 @ aeu. edu. cn the core device for realizing electro-optical conversion, demonstrating great potential for system integration and broad application prospects [ 12, 13 ].
However, the high-frequency response of traditional bulk LN modulators is affected by factors such as“ microwave optical field velocity matching” and“ electrode parasitic parameters,” resulting in limited electro-optic bandwidth [ 14 ]. The inherent size and integration bottlenecks [ 15, 16 ] of bulk LN modulators impede seamless integration with mainstream silicon-based photonic platforms, consequently restricting their deployment in high-density integrated systems.
To overcome this limitation, thin-film technology has become the core direction for the development of LN devices. Internationally, TFLN technology has made groundbreaking progress. The research team from the University of California, Santa Barbara developed a TFLN modulator with a bandwidth of over 100 GHz, realizing efficient electro-optical conversion in the terahertz band [ 16 ]. IBM Research proposed a low-loss Si 3 N 4-TFLN heterogeneous integrated waveguide scheme, laying a foundation
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