Broadband all-optical wavelength conversion (AOWC) for hybrid wavelength-and mode-division multiplexing (WDM-MDM) signals is experimentally demonstrated based on degenerate four-wave mixing in a silicon chip with a parallel dispersion-optimized multimode nonlinear waveguide and mode (de)multiplexers. By simultaneously coupling two modes into the waveguide using an optical fiber array, the intermodal crosstalk is measured to be as low as −25.9 dB for the fundamental mode of the transverse electric mode (TE 0 ) (or −23.6 dB for the first-order mode TE 1 ), and the conversion efficiency is −25.4 dB for TE 0 (or −26.3 dB for TE 1 ) mode. A wide conversion bandwidth of ∼68 nm is measured except for the influence of the crosstalk, which is the first time to experimentally demonstrate the broadband wavelength conversion for MDM signal. Using a 4 × 10 Gbit/s on-off keying (OOK) hybrid WDM-MDM signal, four AOWC channels are obtained on the idlers and the power penalty of each channel is less than 2.7 dB at the bit-error-ratio of 1 × 10 −9 .

We report the designs of on-chip grating couplers for the silicon hybrid plasmonic waveguides, which is the first proposal, to the best of our knowledge, for the direct coupling between a standard single-mode fiber and a hybrid plasmonic waveguide. By leveraging the apodized gratings and a two-stage-taper mode converter, we obtain a theoretical coupling efficiency of 79% (−1.03 dB) at the 1550 nm wavelength and a 3-dB bandwidth of 73 nm between the fiber and a 100 nm-wide silicon hybrid plasmonic waveguide with a bottom metal layer. We further propose grating couplers for three other sorts of silicon hybrid plasmonic waveguides with a metal cap and theoretically achieve good performances with coupling efficiencies larger than 47% and bandwidths larger than 51 nm. The proposed direct coupling scheme can avoid extra insertion losses and additional alignment processes that conventional indirect coupling schemes produce. It is believed to be a new step forward to the CMOS-compatible and large-scale integration based on the plasmonic waveguides.

The authors propose and experimentally demonstrate an on‐chip all‐optical multicasting (AOM) for 40 Gbit/s mode‐division‐multiplexed quadrature phase‐shift keying (MDM‐QPSK) signals based on a parallel dispersion‐engineered multimode non‐linear silicon waveguide. Five dual‐mode multicast wavelengths are successfully obtained on the generate idlers, and the power penalties of all the multicast channels are less than 1.1 dB at the bit error rate (BER) of 3.8 × 10−3. The dual‐mode AOM scheme has the potential to promote the ability of optical cross‐connect in practical hybrid multiplexed networks including MDM channels.