Analytical Model for Abrupt Tapered Mach–Zehnder Interferometer Based on Coupled Mode Theory

An analytical model for light propagation in abrupt tapered single mode fiber Mach-Zehnder interferometer based on coupled mode theory is proposed. The mode propagation process is calculated with this model and compared with previous numerical simulation results. To experimentally verify the model, an in-line Mach-Zehnder interferometer based on abrupt tapered fiber is fabricated and tested in lab. The spectrum calculated by the model matches well with the measured spectrum.