How to Control Light at the Nano-Scale with Localised Surface Plasmon Resonances

Dr Tim Davis

CSIRO Materials Science and Engineering, Clayton, VIC

3:30 pm Friday, 16 May 2014, EN515 Lecture Theatre (EN Building), Hawthorn.

Localised surface plasmons are electric charge oscillations excited on metal surfaces by light. Their short wavelengths enable optical energy to be captured and confined to scales well below the wavelength of light in free space. The strong evanescent electric fields associated with the plasmons couple the optical energy between neighbouring metal structures providing a mechanism for mixing and filtering optical signals. These coupled structures act like nano-scale optical circuits, in analogy with electrical circuits. The plasmons preserve the phase coherence of the incident light which creates opportunities to manipulate the optical phase at the nano-scale. In this talk I will give a brief overview of localised surface plasmon resonances and a simple algebra we have developed for understanding the optical properties of plasmonic circuits. Examples of devices that we have fabricated and tested include chiral structures that respond to the state of circular polarisation, a nano-scale plasmonic circuit that measures optical phase differences and a meta-material of plasmonic circuits that demonstrates all-optical modulation and switching.

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