A single slot micro-ring structure for simultaneous CO2 and CH4 gas sensingWeijia Zhang, Xin Zhang, Xiaowei Zhang, Han Jin, Qinghui Jin and Jiawen JianEur. Phys. J. Appl. Phys., 82 3 (2018) 30502DOI: https://doi.org/10.1051/epjap/2018180093