Design of all-polymer asymmetric Mach–Zehnder interferometer sensors

New design concepts for all-polymer integrated optical Mach-Zehnder interferometers (MZIs) optimized for environmental sensing are presented. Fabricated using large-area printing techniques, these polymer-based components are designed for low cost fabrication while maintaining suitable sensitivities to external refractive index changes. One key aspect in their design is obviating the need for an "interaction window" over one arm of the interferometer, as is usually defined in semiconductor or glass components, but requiring additional lithography, deposition and etching steps not suitable for polymer printing technology. We thus employ an asymmetric MZI, and derive the form of structures with optimized sensitivity and operating characteristics. Using the derived design criteria, experimental verification using a chemical test system finally demonstrates the utility of the approach.