Design of ultra-compact thin-film lithium niobate edge coupler based on micro–nano structure

作者：Yanyan Qin, Xiao-Mei Xue, Lei Shi, Xiao‐Yang Zhang, Tong Zhang · 发表于：Journal of Optics · 年份：2024 · DOI：10.1088/2040-8986/ad3b1a · 被引用次数：9 · 研究领域：Photonic and Optical Devices、Photorefractive and Nonlinear Optics、Advanced Fiber Laser Technologies

Abstract High coupling loss due to fiber-to-chip mode mismatch is considered as one of the main hindrances to thin-film lithium niobate (TFLN) devices to replace their bulk counterparts in engineering applications. In this work, we introduce subwavelength micro–nano structure and slot-strip mode coupling to design an efficient and ultra-compact edge coupler to solve the mismatch issue. The total device length is 130 μ m, which is only 43% of the lengths of general TFLN edge couplers and even 35% shorter than the shortest one while maintaining low coupling loss (0.47 dB/0.38 dB per facet @1550 nm for TE/TM mode). This work provides a case study for the design of integrated photonic devices on the TFLN platform.