A Silicon-Based On-Chip 64-Channel Hybrid Wavelength- and Mode-Division (de)Multiplexer

An on-chip 64-channel hybrid (de)multiplexer for wavelength-division multiplexing (WDM) and mode-division multiplexing (MDM) is designed and demonstrated on a 220 nm SOI platform for the demands of large capacity optical interconnections. The designed hybrid (de)multiplexer includes a 4-channel mode (de)multiplexer and 16-channel wavelength-division (de)multiplexers. The mode (de)multiplexer is comprised of cascaded asymmetric directional couplers supporting coupling between fundamental TE mode and higher-order modes with low crosstalks in a wide wavelength range. The wavelength-division (de)multiplexers consist of two bi-directional micro-ring resonator arrays for four 16-channel WDM signals. Micro-heaters are placed on the micro-resonators for thermal tuning. According to the experimental results, the excess loss is <3.9 dB in one free spectral range from 1522 nm to 1552 nm and <5.6 dB in three free spectral ranges from 1493 nm to 1583 nm. The intermode crosstalks are −23.2 dB to −33.2 dB, and the isolations between adjacent and nonadjacent wavelength channels are about −17.1 dB and −22.3 dB, respectively. The thermal tuning efficiency is ∼2.22 mW/nm over one free spectral range.