Broadband birefringence phase-matched second-harmonic generation in a slightly curved lithium niobate-on-insulator waveguide

doi:10.1364/AO.586578

Broadband birefringence phase-matched second-harmonic generation in a slightly curved lithium niobate-on-insulator waveguide

2026-02-10

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DOI：10.1364/AO.586578

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Lithium niobate-on-insulator (LNOI) waveguides, leveraging their excellent optical field confinement and high nonlinear coefficients, have become an ideal platform for achieving optical frequency conversion. Phasematching interaction strength and bandwidth are critical factors in this process. Here, we propose a scheme using micrometer-scale, slightly curved waveguides on x-cut LNOI to achieve broadband birefringence phase matching (BPM). Experimentally, we observed a broadband second-harmonic generation (SHG) with a bandwidth exceeding 100 nm in the near-infrared regime, achieving the highest, to the best of our knowledge, normalized conversion efficiency of 1.38%/(W cm2) at 1560 nm. For 500 fs pulsed light pumping, an absolute conversion efficiency of over 10% is achieved at a low input power. The approach is suitable for frequency conversion of ultrashort lasers on a chip. This approach presents a promising alternative to periodically poled lithium niobate (PPLN) for broadband frequency conversion applications. (c) 2026 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.

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WAVELENGTH CONVERSION

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Broadband birefringence phase-matched second-harmonic generation in a slightly curved lithium niobate-on-insulator waveguide

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