Figure 3.

The designed two-parameter SIMRR sensor. (a) Structural diagram of the designed two-parameter SIMRR sensor. The surfaces of two half-ring waveguides in the left and right are separately coated by two sensitive materials to detect two kinds of gases. (b) when two gases to be detected are only exposed to two half-ring waveguides in the left and right, it is assumed that their effective refractive index changes are the Gaussian and Lorentz functions of of wavelength, respectively. At C1 = C2 = 5%, their waveguide effective refractive indices can be separately given by n_eff1 = n_eff + ∆n_eff1 and n_eff2 = n_eff + ∆n_eff2.