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Ultrafast all-optical tuning of direct-gap semiconductor metasurfaces

 
: Shcherbakov, M.R.; Liu, S.; Zubyuk, V.V.; Vaskin, A.; Vabishchevich, P.P.; Keeler, G.; Pertsch, T.; Dolgova, T.V.; Staude, I.; Brener, I.; Fedyanin, A.A.

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Fulltext ()

Nature Communications 8 (2017), Art.17, 6 pp.
ISSN: 2041-1723
English
Journal Article, Electronic Publication
Fraunhofer IOF ()

Abstract
Optical metasurfaces are regular quasi-planar nanopatterns that can apply diverse spatial and spectral transformations to light waves. However, metasurfaces are no longer adjustable after fabrication, and a critical challenge is to realise a technique of tuning their optical properties that is both fast and efficient. We experimentally realise an ultrafast tunable metasurface consisting of subwavelength gallium arsenide nanoparticles supporting Mie-type resonances in the near infrared. Using transient reflectance spectroscopy, we demonstrate a picosecond-scale absolute reflectance modulation of up to 0.35 at the magnetic dipole resonance of the metasurfaces and a spectral shift of the resonance by 30 nm, both achieved at unprecedentedly low pump fluences of less than 400 μJ cm–2. Our findings thereby enable a versatile tool for ultrafast and efficient control of light using light.

: http://publica.fraunhofer.de/documents/N-509739.html