Mode Converter and Multiplexer With a Subwavelength Phase Shifter for Extended Broadband Operation

On-chip mode converters and multiplexers are fundamental components to scale the capacity of silicon optical interconnects by using different spatial modes waveguides. Recently, we proposed a low loss compact converter multiplexer consisting subwavelength-engineered multimode interference coupler, tapered waveguides as phase shifter symmetric Y-junction. However, narrow spectral response limited device crosstalk performance. In this work, demonstrate that use subwavelength grating with phase-shift errors substantially reduces expands operational bandwidth. A complete multiplexer-demultiplexer link two devices in back-to-back configuration was fabricated 220-nm silicon-on-insulator platform. Experimental measurements show insertion below 2 dB less than −17 over bandwidth 245 nm (1427 – 1672 nm).