Gap Plasmon Phase Modulator (IMAGE)

Rutgers University

Gap Plasmon Phase Modulator

Caption

Surface plasmons are propagating electronic oscillations localized to metal-insulator (e.g. gold-air) interfaces. Gap plasmons (GPs) arise when two such interfaces are separated by a narrow gap across the insulator layer, transversely confining the electromagnetic energy in an MIM (metal-insulator-metal) waveguide. In this illustration, a free-space excitation laser (vertical light on the right) couples to GPs (alternating red/blue light) in a gold/air/gold nanofabricated waveguide. A grating is used to match the laser light momentum with to a GP. The GP propagates through the waveguide under free-floating micro-beams in the top gold layer (color coded to show depth). When the beams are electrically actuated towards the bottom gold layer, the effective refractive index of the waveguide increases under the beams, phase-retarding the GP.

Credit

Brian Dennis, Rutgers University

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