Mirror-terminated Mach-Zehnder interferometer based on SiNOI slot and strip waveguides for sensing applications using visible light

In this work, a highly sensitive sensor based on silicon nitride (SiN) waveguide is proposed that can be used for gas sensing using visible light. The whole uses dioxide (SiO 2 ) cladding while the arm fluidic such as water. device loop-mirror terminated (LMT) Mach-Zehnder interferometer (MZI), where reference exposed to SiO medium, medium leading change in refractive index of cladding. performance overall optimized by optimizing design all components structure one one. sensitivity both strip and slot types analyzed gaseous order compare their sensitivities select dimensions results highest sensitivity. Transverse-electric (TE) polarization considered study waveguide, higher founded with respect transverse-magnetic (TM) polarization. field confinement region investigated verified mode solver, optimum are obtained finite difference eigenmode time domain solvers. With length 150 μm only, achieves about 1,320 nm/RIU figure-of-merit (FOM) high 641 RIU −1 at wavelength 650 nm, which reported FOM up author’s knowledge. Higher values possible employing longer arm.