“…Compared with these two types of sensors, optical gas sensors have a different principle of light absorption. Therefore, optical sensors have multiple advantages over electrochemical and semiconductor gas sensors, such as the feature of fast response, selective, sensitive and non-destructive sensing, high resistivity to electromagnetic noise, and intrinsically safe detection [ [6] , [7] , [8] , [9] , [10] , [11] , [12] , [13] ]. They are widely used in numerous fields of combustion diagnostics, atmospheric monitoring and life sciences [ [14] , [15] , [16] , [17] , [18] ].…”