Circular Dichroism in Higher‐Order Diffraction Beams from Chiral Quasiplanar Nanostructures

Miniaturization down to the nanoscale has enabled a new paradigm of ultrathin optical devices, capable of manipulating the direction, polarization, and frequency of light. Great interest is drawn by the promising prospects of deep‐subwavelength material dimensions. However, interesting properties an...

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Bibliographic Details
Published in:Advanced optical materials 2018-06, Vol.6 (11), p.n/a
Main Authors: Kuppe, Christian, Williams, Calum, You, Jie, Collins, Joel T., Gordeev, Sergey N., Wilkinson, Timothy D., Panoiu, Nicolae‐Coriolan, Valev, Ventsislav K.
Format: Article
Language:English
Subjects:
Babinet's principle
Beams (radiation)
chirality
circular dichroism
Dichroism
Diffraction
Gold
Materials science
Miniaturization
nanophotonics
Optics
Polarization
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Summary:Miniaturization down to the nanoscale has enabled a new paradigm of ultrathin optical devices, capable of manipulating the direction, polarization, and frequency of light. Great interest is drawn by the promising prospects of deep‐subwavelength material dimensions. However, interesting properties and opportunities offered by structures with sizes comparable to the wavelength of light appear to have been overlooked. Here, quasiplanar chiral arrays made of gold are considered and show that higher‐order diffracted beams can yield extremely large chiroptical responses for optical frequencies. The chosen sample geometry demonstrates spectrally tunable polarization conversion and extremely large circular dichroism. Experimental and numerical data are in good agreement, for both sample chiral forms, and for the complementary geometries under Babinet's principle. Specifically, the experimental results show that the fractional circular dichroism (CD) can be as high as 20%, in the third‐order diffraction beam. Based on the numerical results, a great potential for improvement is anticipated, which makes higher‐order diffraction CD a very promising candidate for ultrathin optical applications. A highly sensitive diffraction setup for circular dichroism measurements in higher‐order diffracted beams is shown for quasiplanar chiral samples. It is demonstrated that the samples give the strongest chiroptical response in the third‐order diffracted beam. Numerical and experimental data are in good agreement, further validated by using Babinet's principle.
ISSN:2195-1071
2195-1071
DOI:10.1002/adom.201800098