Polymeric Waveguide MZI Thermo-Optic Mode Switch Based on Asymmetric Directional Coupler

We propose and fabricate a polymeric thermo-optic mode switch based on a Mach-Zehnder interferometer (MZI) by connecting two asymmetric directional couplers formed with a single-mode waveguide (SMW) and a two-mode waveguide (TMW). Thin-film heaters were deposited on the arms of the MZI to realize the switching function. The LP01 mode in the SMW and the LP11a mode in the TMW can be converted to each other by driving the voltage supplied to the heater. Our typical fabricated device with polymer material shows extinction ratios higher than ~11 dB in the C-band. The switching power measured at 1550 nm is lower than 10 mW and the switching rise time and fall time are 540.0 μs and 440.0 μs, respectively. The device could find applications in reconfigurable mode-division-multiplexing systems.