Method of Generating Frequency Tunable Resonant Scatterers

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Finite Difference Time Domain calculation of the energy density around a metal nanoparticle under plane wave excitation
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Researchers
Aristide Dogariu, Ph.D.
Pieter Kik, Ph.D.
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John Miner
Assistant Director 407.882.1136
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Frequency tunable resonant apparatus

US Patent 7,471,388 B1

Apparatus, methods, systems and devices for enhancing optical emissions by tuning the resonant states of conductive structures

In many applications, such as optical, mechanical and acoustic sensing, displays of optical information are based on scattering of optical fields with specific frequencies on various scattering structures. These actions are significantly more efficient when the scatterer is brought into a resonant regime. Metals, or more generally conductors, have special optical properties exhibited by their coherent charge density oscillations. Similarly, metal nanoparticles exhibit collective electron oscillations that lead to pronounced resonances at specific optical frequencies. These resonances become apparent in extinction measurements due to resonantly enhanced scattering and absorption. Associated with these resonances are localized electromagnetic fields with significantly enhanced strength relative to that of the excitation source. The ability to actively tune these resonances plays an important role in applications that benefit from enhanced electric fields, localization of light, optical absorption, and optical scattering. Tune-ability of a particle’s resonant state is therefore highly desirable. Consequently, there is a need to be able to actively tune the resonant frequency of metal nanoparticles.

Technical Details

The present invention is a novel approach for building frequency tunable resonant scatterers. It is able to tune the resonance frequency of a conductive structure such as metal nanoparticles, to a broad range of excitation wavelengths. The method offers significant benefits such as: enhanced sensitivity, increased selectivity, and greater ability to integrate with microscopic structures.

Benefits

  • Allows for continuous resonances tuning over a large range (>100nm)
  • Provides enhanced sensitivity and selectivity
  • Highly integratable with microscopic structures

Applications

  • Miniature biochemical detector arrays based on Surface Enhanced Raman Scattering (SERS)
  • High resolution displays based on nanoscale tunable scatterers
  • Optical displacement sensors
  • Acoustic sensors
  • Tunable waveguide filters