US 8,009,356 B1Granted

Tunable surface plasmon devices

AssigneeSandia Corporation

InventorsEric A. Shaner, Daniel Wasserman

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Abstract

A tunable extraordinary optical transmission (EOT) device wherein the tunability derives from controlled variation of the dielectric constant of a semiconducting material (semiconductor) in evanescent-field contact with a metallic array of sub-wavelength apertures. The surface plasmon resonance wavelength can be changed by changing the dielectric constant of the dielectric material. In embodiments of this invention, the dielectric material is a semiconducting material. The dielectric constant of the semiconducting material in the metal/semiconductor interfacial region is controllably adjusted by adjusting one or more of the semiconductor plasma frequency, the concentration and effective mass of free carriers, and the background high-frequency dielectric constant in the interfacial region. Thermal heating and/or voltage-gated carrier-concentration changes may be used to variably adjust the value of the semiconductor dielectric constant.

Claims17

Dependent claims

A tunable optical filter, comprising:

a substrate, the substrate having a front side and a back side and being transparent at a light transmission wavelength;
a doped region of the substrate, wherein the doped region has a doping level suitable for resistive heating by passage of a current;
a metallic extraordinary optical transmission grating located proximate the front side of the substrate and having a periodic array of apertures therethrough, the apertures each having a maximum cross-sectional dimension less than the light transmission wavelength and a periodic spacing corresponding to approximately resonance with the light transmission wavelength;
a dielectric layer within an evanescent-field distance of the extraordinary optical transmission grating and with a temperature-dependent dielectric constant, the dielectric layer being situated for heating as a consequence of the passage of the current through the doped region of the substrate, whereby the periodic array of apertures and the temperature-dependent dielectric constant produce a tuned surface plasmon passband at approximately the light transmission wavelength;
and
at least one contact in electrical contact with the doped region.

3 more elements

Dependencies are inferred from the claim text.