Tunable surface plasmon devices
| DWPI Title: Tunable optical filter e.g. double bandpass filter, has dielectric layer heated as consequence of passage of current through doped region and contacts in electrical contact with doped region |
| 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. |
| Use: Tunable optical filter e.g. thermally tuned SP extraordinary optical transmission (EOT) filter such as double bandpass filter and passive bandpass filter. |
| Advantage: The filter minimizes or avoids free-carrier effects by using the substrate that is insulated, semi-insulated or lightly doped, thus improving filter transparency. The filter applies voltage to adjust the passband of an EOT grating without the need to change gross periodicity or aperture size and shape of the grating, thus allowing fabrication of the filter operated at a precisely tuned passband even when variations in the periodicity and aperture dimensions occur due to variability during grating fabrication. The filter can be readily and inexpensively formed to operate at different wavelengths while using the same periodicity and aperture characteristics for EOT. |
| Novelty: The filter has a dielectric layer i.e. semiconductor layer, formed within an evanescent-field distance of an extraordinary optical transmission grating i.e. metal layer. The layer is heated as a consequence of a passage of current through an n-type doped region of a semiconductor substrate (1), where a periodic array of sub-wavelength apertures produces a tuned surface plasmon (SP) passband approximately at a light transmission wavelength. A set of contacts e.g. semitransparent film contacts, is in electrical contact with the doped region. |
| Filed: 6/12/2008 |
| Application Number: US2008137882A |
| Tech ID: SD 10692.1 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
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