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Electronics & Photonics (EP)

   

Plasmonics nanowires: manipulation of light at nanometer scale

1.3 Plasmonics nanowires: manipulation of light at nanometer scale

Inter-RI collaboration: DSI

Plasmons are a physics phenomenon based on the optical properties of metals; they are represented by the energy associated with charge density waves propagating in matter through the motions of large numbers of electrons. Those plasmons that are confined to surfaces and which interact strongly with light are known as surface plasmons, also called plasmonics. Therefore, plasmonics is considered as a truly nanophotonic module for communications, imaging and spectroscopy by exploiting localized and propagating surface plasmons that access nanometer-scale wavelengths at optical frequencies.

Plasmonics has a variety of potential applications. Plasmonic nanowires can be much thinner than conventional wires, and could support much higher frequencies, so plasmonics has been considered a mean of transmitting information on computer chips. The plasmonic resonance of metallic films, several interacting metallic nanorods, nanowires or nanoholes can be used to guide, filter, switch or manipulate light. Due to the availability of extremely small wavelengths in plasmonics means that it could be utilized in high resolution lithography and microscopy. In addition, the surface-plasmon-based sensors can also find uses in gas sensing, biological environments such as immuno-sensing and electrochemical studies.

In this project, we focus on the modeling and analysis of plasmonic nanosructures for various applications such as near field optics, guiding light, and nanosensor. We not only develop new and efficient numerical techniques for the specific problem but also master the commercial software in order to possess the powerful modeling and analysis tool to design the plasmonic devices throughout the research process. Several in-house codes based on frequency- and time-domain methods, such as the integral equation method, scattering matrix method as well as finite-difference time domain method, have been developed at IHPC. These methods enable full characterization of the optical properties of plasmonic nanostructures. Using in-house codes such as the integral equation method and scattering matrix method, some of the plasmonic applications which we have investigated are shown in the figures.

The result, in Fig. 1, shows that the strong field enhancement, like-dipole, can be obtained at the surrounding area of an elliptical silver nanowire having the overall size of 40 nm x 10 nm. The plasmonic waveguide consisting of coupled silver nanowires, as shown in Fig. 2, is helpful used to guide the light at the tiny cross section of 50 nm. The last result, in Fig. 3, demonstrates that the silver nanowire with the radius of 25 nm can be used as nanosensor to detect its surrounding medium. The shift of extinction peak is due to the variation of the reflective index of different surrounding medium.

Near field intensity is strongly enhanced around the elliptical
silver nanowire at the resonance,
Nanoscale plasmonic waveguide for guiding light at the cross section of
50 nm
Plasmonic nanowire for nanosensing application.

 

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This page is last updated at: 10-MAY-2010