A Novel Structure of Multi-Mode Interferometer with Low Excess Loss

Multi-mode interferometer (MMI), which can provide precise splitting with low imbalance, high thermal stability, and large optical bandwidth, are essential components for high performance Mach-Zehnder Interferometers (MZI)-based optical modulators, widely used in optical communication and optical computing application. In this work, we theoretically and experimentally report a multi-mode interferometer device of novel structure with expected performance. Compared with traditional MMI structure, our strategy employs two-steps taper in the ports to achieve low excess loss and large multimode waveguide size to increase fabrication tolerance.