Xiao Xia Ma, Zhi Ying Zhao, Hao Yao, Jia Yao Deng , Jie Yun Wu , Zhe Feng Hu, and Kai Xin Chen, “Compact and Highly Sensitive Refractive Index Sensor Based on Embedded Double-Ring Resonator Using Vernier Effect,” IEEE Photonics J., 15(1), 6800109, 2023.