Scalable, fiber-compatible lithium-niobate-on-insulator micro-waveguides for efficient nonlinear photonics
Yuting Zhang, Hao Li, Tingting Ding, Yi‐Wen Huang, Longyue Liang, Xuerui Sun, Yongzhi Tang, Jiayu Wang, Shijie Liu, Yuanlin Zheng, Xianfeng Chen
Abstract
Efficient wave mixers based on lithium-niobate-on-insulator (LNOI) hold great potential for next-generation photonic integrated circuits in both classical and quantum optics. However, achieving high-performance nonlinear photonic devices readily suitable for scalable, fiber-compatible applications remains challenging. Here, we report on the fabrication of LNOI micrometer waveguides, i.e., micro-waveguides, with a combination of ultraviolet lithography and deep dry etching technology for efficient nonlinear photonics applications. We fabricate periodically poled LNOI micro-waveguides with a cross section of ∼3×4µm 2 and demonstrate a fiber–chip–fiber second-harmonic generation conversion efficiency of 1320%/W with an insertion loss of 3.8 dB at the telecommunication band. We also demonstrate high-quality photon pair generation via spontaneous parametric downconversion with a flux of 178 MHz/mW at sub-mW pump power and coincidence-to-accidental ratio >8000 at microwatt pump power. The overall performance in both applications is on par with that of state-of-the-art counterparts using thin-film lithium niobate nano-waveguides. The technique would make micrometer-thick LNOI an attractive platform for ready applications in nonlinear and quantum optics.