Dual-Mode Variable Optical Attenuator Based on Polymer Waveguide Mach–Zehnder Interferometer

The variable optical attenuator is one of the key components in optical communication system, but it is scarce for mode division multiplexing system. Here, we designed and experimentally demonstrated an ultra-broadband dual-mode variable optical attenuator based on Mach–Zehnder interferometer with thermo-optic phase shifters. We fabricated the device with polymer waveguide and characterized the function of the variable optical attenuator. The presented device can attenuate E11 and E12 modes simultaneously at a low power-consumption (
$\sim $
4.8 mW) over 1500 - 1620 nm, which proves that our device is mode-insensitive and wavelength-insensitive. The presented variable optical attenuator can be widely used in mode division multiplexing system where mode-insensitive attenuating or switching is needed.