Nanoscale photonics of structural transformations in gallium

Zheludev, Nikolay I., Fedotov, Vassili A., MacDonald, Kevin F., Stevens, G.C., Pochon, Sebastien and Woodford, M. (2002) Nanoscale photonics of structural transformations in gallium. Cao, Guozhomg and Kirk, Wiley P. (eds.) Annual meeting: Nanoscale Optics and Applications, , Seattle, United States. 01 Jul 2002. (doi:10.1117/12.451621).

Abstract

We have found recently that Gallium, confined at an interface with silica, responds dramatically to low power optical excitation when held at temperatures close to its melting point (29.8°C). Intensities of just a few kW/cm² can reversibly modulate the intensity (by up to 40%) and phase (by as much as several degrees) of reflected light as the result of a light-induced structural transition occurring in a layer of gallium of only a few nm thick. Here, we report that this concept - of achieving a nonlinearity via a light-induced transformation in a confined solid at a temperature close to a phase transition temperature - can also be applied to gallium nanoparticles. We present the transient all-optical switching characteristics of gallium nanoparticle films comprising particles, typically 80 nm in diameter, which were formed directly on the ends of optical fibers using a new light-assisted self-assembly technique. We also report, for the first time, that this light-induced structural transition in gallium confined at an interface with silica underlies a new mechanism for photoconductivity. In our opinion, the exploitation of the light-induced phase transition in gallium may be a means of enabling the development of nanoscale photonic devices.

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Contributors

Author: Nikolay I. Zheludev

Author: Kevin F. MacDonald

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