Design a Flexible Multimode Switching Based on Silicon Photonic Integrated Circuits for a Mode Division Multiplexing Network

We propose a compact multimode switch for reconfigurable applications in mode division multiplexing networks. The device can switch and convert flexibly two modes between simultaneous input and output ports. The structure of the device is built on the arrangement of easy-to-fabricate components such as 2x2 Multimode interferometers, 1x2 Y-shaped couplers, and butterfly Phase Shifters. Through the beam propagation method (BPM), we show that by controlling the phase of the phase shifters at 0, 90, or -90 degrees, flexible mode switching scenarios can be realized. The results demonstrate that the insertion loss and crosstalk are always less than 2 dB and -26 dB, respectively, over a wide wavelength range from 1500 nm to 1600 nm.