Single Mode SU8 Polymer Based Mach-Zehnder Interferometer for Bio-Sensing Application

This paper explains the influence of different parameters to the sensitivity of an optical waveguide Mach‐Zehnder Interferometer (MZI) for real time detection of biomolecules. The sensing principle is based on the interaction of evanescence field with the biomolecules that get immobilized on sensing arm. The sensitivity has been calculated by varying the sensing window length, wavelength and concentration of bio‐analyte. The maximum attainable sensitivity for the preferred design is the order of 10−8 RIU at 840 nm wavelength with a sensing window length of 1cm. All the simulation work has been carried out with Opti‐BPMCAD for the optimization of MZI device parameters. The SU8 polymers are used as a core and clad material to fabricate the waveguide. The refractive index of cladding layer is optimized by varying the curing temperature for a fixed time period and the achieved index difference between core and clad is Δn = 0.0151. The fabricated MZI device has been characterized with LASER beam profiler at 84...