CUDOS@USyd Research

Surface plasmon theory and applications...

Ross McPhedran, Nicolae-Alexandru Nicorovici, Christian Karnutsch

Light interacting with systems containing metallic elements can create surface plasmons and therefore strong local fields, enhanced non-linear effects and surprising transmission through small holes. In a project to commence in 2006 we will investigate the basic physics of plasmons in structured metallic systems. Metals give high contrast in optical elements, permitting nano-scale structures to interact strongly with light, and we will provide accurate design rules to control light absorption within them. Our aim is to investigate a range of applications of surface plasmons in linear and non-linear photonic systems.

Plasmonics and cloaking

Graeme Milton (University of Utah), Ross McPhedran (University of Sydney), Nicolae-Alexandru Nicorovici (University of Technology Sydney and University of Sydney)

The making of an object invisible through some cloaking device is commonly regarded as science fiction. However, we have discovered a new phenomenon in electromagnetism which translates into a new mechanism for invisibility or cloaking.

Specifically, regions of anomalous localized resonance, such as occur near superlenses, are shown to lead to cloaking effects. This occurs when the resonant field generated by a polarizable line or point dipole acts back on the polarizable line or point dipole and effectively cancels the field acting on it from outside sources, so it has essentially no response to the external field. Numerically and analytically we see that the polarizable line or point dipole is effectively invisible to the external time harmonic field. Cloaking is proved in the quasistatic limit for finite collections of polarizable line dipoles that all lie within a specific distance from a coated cylinder having a shell dielectric constant close to -1 and a matrix and core dielectric constant equal to 1. Cloaking is also shown to extend to the Veselago superlens outside the quasistatic regime: a polarizable line dipole located less than a distance d/2 from the lens, where d is lens thickness, will be cloaked due to the presence of a resonant field in front of the lens. Also a polarizable point dipole near a slab lens will be cloaked in the quasistatic limit. The hope of using cloaking to see the interior of an object by making half of it invisible remains an intriguing possibility.

Images for cloaking by reaction: Click on the image above to link to the quicktime movie.

Presentation and slides on cloaking

Presentation by Graeme W. Milton, "Cloaking: A new phenomenon in Electromagnetism," ETOPIM 7, 2006.
Presentation by Ross McPhedran, "From Homeopathy to Cloaking by Plasmonic Resonance," School of Physics Colloquium, University of Sydney, 2006.
The following animation (.exe file - [ESC] to stop) shows a coated cylinder with core and shell dielectic constants of 1 and -1+i*10-7, and core and shell radii of 2 and 4 respectively, placed in a uniform electric field. A polarizable molecule moves from the right. The dashed line marks the circle where the cloaking phenomenon occurs. The polarizable molecule has a strong induced dipole moment and perturbs the field around the coated cylinder strongly. It then enters the cloaking region, and it and the coated cylinder do not perturb the external field.

Presentations and slides on plasmonics

Presentation by Nicolae-Alexandru Nicorovici, "Optical Resonances of Cylinder and Sphere Clusters in the Quasistatic Limit," ETOPIM 7, 2006.

Some media releases

References

Authorised by: Prof. Ben Eggleton
Maintained by: Bill Corcoran
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