On-chip reconfigurable and scalable optical mode multiplexer/demultiplexer based on three-waveguide-coupling structure

Reconfigurable optical mode multiplexers/demultiplexers have attracted increasing attention in the academic community, because they enable convenient construction of flexible and complex on-chip optical networks. Here, we propose and demonstrate a scheme of reconfigurable and scalable optical mode multiplexer/demultiplexer with large operation bandwidth, based on three-waveguide-coupling structures. As proof of concept, a reconfigurable device that can multiplex input signals to the fundamental and first-order quasi-transverse electric mode is fully fabricated and demonstrated successfully. Static response spectra show that the optical crosstalk at the output ports of the device are less than -14.3 dB and -13.7 dB over the entire C band (> 40 nm), respectively. The dynamic performance with data transmission speeds of 40 Gbps for each multiplexing channel are also demonstrated successfully. The presented device is believed to be a potential candidate for future on-chip optical network with large-scale integration, flexible functionality, and low cost.