Integrated switchable mode exchange for reconfigurable mode-multiplexing optical networks.

We propose and experimentally demonstrate an on-chip switchable mode exchange utilizing a Mach-Zehnder interferometer assisted by a phase shifter. The switchable functionality, which is essential for an advanced and reconfigurable optical network, can be realized by controlling the induced phase difference. The measured extinction ratio is ∼24  dB over the C band for OFF-ON switchover. For demonstration, open and clear-eye diagrams can be observed when processing non-return-to-zero on-off keying signals at 10 Gb/s. The bit error rate measurements indicate a reasonable power penalty of less than 1 dB for two-mode exchange. The proposed device can further promote advanced and flexible mode-multiplexing optical networks.