Ultra-compact and high-performance silicon mode (de)multiplexer based on a tapered bent asymmetric directional coupler

We propose and experimentally demonstrate the ultra-compact on-chip silicon mode (de)multiplexers [(De)MUXs] based on a tapered bent asymmetric direction coupler. By combining the advantages of tapered asymmetric directional coupler and bent directional coupler, low loss, broad bandwidth, and good robustness against fabrication variations can be obtained within ultra-compact coupling length. The coupling length of the proposed TE₁-TE₀ and TE₂-TE₀mode (de)multiplexers is less than 8.7 µm. Experimental results reveal that, over the wavelength range from 1.534 μm to 1.6 μm, the insertion loss is lower than 1.4 dB and 1.55 dB for the TE₁-TE₀ and TE₂-TE₀ mode multiplexing, respectively, and the crosstalk is lower than -10dB.