Broadband second-harmonic generation in thin-film lithium niobate microdisk via cyclic quasi-phase matching

• DOI: 10.3788/col202422.031903
• Publication Date: 2024-03-25T03:26:40Z
• Authors: Jiefu Zhu; Tingting Ding; Xuerui Sun; Fengchao Ni; Hao Li; Shijie Liu; Yuanlin Zheng; Xianfeng Chen

Whispering-gallery-mode (WGM) microresonators can greatly enhance light–matter interaction, making them indispensable units for frequency conversion in nonlinear optics. Efficient wave mixing requires stringent simultaneous optical resonance and phase-matching conditions. Thus, it is challenging to achieve efficient over a broad bandwidth. Here, we demonstrate broadband second-harmonic generation (SHG) the x-cut thin-film lithium niobate (TFLN) microdisk with quality factor above 107 by applying cyclic quasi-phase-matching (CQPM) mechanism, which intrinsically applicable operation. Broadband SHG of continuous-wave laser maximum normalized efficiency ∼15%/mW achieved bandwidth spanning 100 nm telecommunication band. Furthermore, femtosecond lasers, supercontinuum amplified spontaneous emission band also experimentally observed. The work beneficial integrated photonics devices like converters comb generator based on second-order nonlinearity TFLN platform.