Xue Cuiwei, Liao Rujun, Li Xiaoman, Wu Weiping, Jin Xin, Quan Xueling, Qu Minni, Wu Liying, Xu Liping, Fu Liucheng, Liu Min, Duan Huanan, Cheng Xiulan
Opt Lett. 2025 Feb 1;50(3):864-867. doi: 10.1364/OL.549856.
A perfectly vertical grating coupler (GC) on X-cut lithium niobate on insulator (LNOI) platform is designed and demonstrated. The optimized random grating structure of GC is designed by an inverse design method and exhibits a simulated coupling efficiency of approximately -2.52 dB and measured coupling efficiency of approximately -3.18 dB at a communication wavelength of 1550 nm. This is the highest, to the best of our knowledge, measured result yet reported compared to the coupling efficiency of LNOI grating couplers without reflector in existing literature, regardless of the angle of incidence and the thickness of lithium niobate. The fabrication tolerance is investigated, and the discrepancy between simulation and experiment is analyzed.
设计并展示了一种基于绝缘体上X切铌酸锂（LNOI）平台的完全垂直光栅耦合器（GC）。通过逆向设计方法设计了GC的优化随机光栅结构，在1550nm通信波长下，模拟耦合效率约为-2.52dB，实测耦合效率约为-3.18dB。据我们所知，与现有文献中无反射器的LNOI光栅耦合器的耦合效率相比，无论入射角和铌酸锂厚度如何，这是迄今报道的最高实测结果。研究了制造公差，并分析了模拟与实验之间的差异。
