Three-port mode-(de)interleaver in silicon waveguide

•We propose a three-port silicon mode-(de)interleaver (TSMIL).•The design criteria developed for multi-port mode-(de)interleaving is presented.•The designed six-mode TSMIL has a low excess loss and a low mode crosstalk.

We propose a three-port silicon mode-(de)interleaver (TSMIL) using an asymmetric multi-arm Y-junction to flexibly address optical modes and efficiently increase the ports with less cascaded stages in mode-division multiplexing transmission. The design criteria developed for multi-port mode-(de)interleaving is presented. The qualitative functionality of the device is mainly determined by the widths of the arms. The example of a six-mode TSMIL is designed and analyzed in detail. Numerical simulations show that a low excess loss (<1 dB) and a low mode crosstalk (<−17 dB) over a 60 nm wavelength range can be obtained.