Integrated ultracompact and broadband wavelength demultiplexer based on multi-component nano-cavities.

Integrated nanoscale photonic devices have wide applications ranging from optical interconnects and optical computing to optical communications. Wavelength demultiplexer is an essential on-chip optical component which can separate the incident wavelength into different channels; however, the experimental progress is very limited. Here, using a multi-component nano-cavity design, we realize an ultracompact, broadband and high-contrast wavelength demultiplexer, with 2.3 μm feature size, 200 nm operation bandwidth (from 780 nm to 980 nm) and a contrast ratio up to 13.7 dB. The physical mechanism is based on the strong modulation of the surface plasmon polaritons induced by the multi-component nano-cavities, and it can be generalized to other nanoscale photonic devices. This provides a strategy for constructing on-chip photon routers, and also has applications for chip-integrated optical filter and optical logic gates.