2×2 multimode optical switch for large-capacity on-chip optical interconnect
We propose a silicon 2×2 optical switch which can simultaneous manipulate wavelength division multiplexing and mode division multiplexing signals. It is composed of broadband mode multiplexers, demultiplexers and single mode optical switch elements. For demonstration, we design and fabricate a prototype device using asymmetric directional coupler and Mach-Zehnder optical switch elements which can manipulate four modes and multi-wavelengths from 1525 nm to 1565 nm. The optical crosstalk is less than 18.9 dB and the 10%–90% switching time is ∼19 μs. This device can be a key component for constructing simultaneous WDM and MDM optical networks to further increase the communication capacity.