Experimental Comparison of Integrated Circuit Mach-Zehnder Interferometers for Different Types of Output Combiners

In this work, silicon photonic integrated circuit Mach-Zehnder interferometers are evaluated from the output coupler point of view. Simulated results and analytical evaluations are presented to support the design choices. The experimental data is compared against the simulations. The use of correct simulation models is emphasized. The experimental results show that the best overall performance is demonstrated by the MZI configuration with adiabatic coupler. The broadband directional coupler has also good performance. The worst performance is demonstrated by the ordinary directional coupler.