Analysis of the Mach–Zehnder interferometer waveguide structure for refractive index measurement

Accurate measurement of concentrations of solids, gases and liquid have become more and more important in chemical analysis, biomedical, food, environmental monitoring and in the semiconductor manufacturing area. The present study was based on Mach–Zehnder Interferometer Waveguide (MZIW) structure for Refractive Index (RI) measurement application and deals with interferometer using single mode transmission. Waveguide under consideration is very small in size and faces difficulty in the light guiding into it. Instead of the penetration depth of evanescence wave, light guiding efficiency dominates the detection sensitivity of structure. So careful light guiding is an important aspect of the photonics structure. As the concentration and hence the refractive index changes the path length of the light in measurement arm of the structure and this change in path length produces the corresponding changes in phase shift of light passing through it. Other arm is reference arm in which phase shift remains constant. Tests have been carried out using Beam Propagation Method technique using Beam PROP software to analyze MZIW structure and measurement of refractive index of medium using this structure. We examine the behavior of MZIW structure using Y branches and establish the general design principles. It has capacity to eliminate external effects in refractive index measurement application.