Light absorption by interference of radiation in a metamaterial - an anti-LASER

Zhang, J., MacDonald, K.F. and Zheludev, N.I. (2012) Light absorption by interference of radiation in a metamaterial - an anti-LASER. SPIE Photonics Europe 2012, , Brussels, Belgium. 16 - 19 Apr 2012.

Abstract

We demonstrate for the first time that a planar photonic metamaterial (a single layer of nanostructured metal less than one tenth of a wavelength thick) can, via a coherent interaction, resonantly absorb all of the light incident on it.
The coherent absorption phenomenon described here is a metamaterial analogue of the recently reported optical cavity 'coherent perfect absorption' phenomenon - the time-reversed counterpart of conventional lasing. It is a narrowband phenomenon arising from the tailored interplay of interference and absorption between counter-propagating beams in a dissipative medium and was recently demonstrated experimentally in a bulk optical resonator [Wan, et al., Science 331, 889 (2011)].
Here we show that a similar effect may be observed in a single sub-wavelength metallic metamaterial film exploiting plasmonic resonant absorption. We experimentally demonstrate coherent perfect absorption in a 50 nm thick gold metamaterial at a wavelength of 633 nm and show that the level of absorption can be coherently controlled by adjusting the mutual phase of the interfering beams.
The metamaterial coherent perfect absorber is the time-reversed counterpart of the 'lasing spaser' (a coherent source of optical radiation fuelled by plasmonic oscillations) and may serve applications in optical modulators, transducers, switches or sensors.

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Contributors

Author: K.F. MacDonald

Author: N.I. Zheludev

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