Multi-color photon sorting in plasmonic microcavities

Multi-color photon sorting is realized on the basis of plasmonic microcavities etched in a gold film coated with a polyvinyl alcohol layer. Both wide-band unidirectional surface plasmon polariton launchers and plasmonic microcavities are integrated on-chip. The physical mechanism of the multi-color photon sorting function is attributed as the plasmonic stop bands prohibiting the surface plasmon polariton propagation in a broad wavelength range, while the plasmonic microcavities selectively permit several surface plasmon polaritons to pass, on the basis of the photon tunneling effect. Incident continuous wave lasers with wavelengths of 800, 840, and 880?nm are separated, and decoupled from different output ports. The operating wavelength can be tuned by adjusting the refractive index of the covering polymer layer.