Particle manipulation beyond the diffraction limit using structured super-oscillating light beams

The diffraction-limited resolution of light focused by a lens was derived in 1873 by Ernst Abbe. Later in 1952, a method to reach sub-diffraction light spots was proposed by modulating the wavefront of the focused beam. In a related development, super-oscillating functions, that is, band-limited fun...

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Published inLight, science & applications Vol. 6; no. 9; p. e17050
Main Authors Singh, Brijesh K, Nagar, Harel, Roichman, Yael, Arie, Ady
Format Journal Article
LanguageEnglish
Published London Nature Publishing Group UK 08.09.2017
Springer Nature B.V
Nature Publishing Group
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Summary:The diffraction-limited resolution of light focused by a lens was derived in 1873 by Ernst Abbe. Later in 1952, a method to reach sub-diffraction light spots was proposed by modulating the wavefront of the focused beam. In a related development, super-oscillating functions, that is, band-limited functions that locally oscillate faster than their highest Fourier component, were introduced and experimentally applied for super-resolution microscopy. Up till now, only simple Gaussian-like sub-diffraction spots were used. Here we show that the amplitude and phase profile of these sub-diffraction spots can be arbitrarily controlled. In particular, we utilize Hermite–Gauss, Laguerre–Gauss and Airy functions to structure super-oscillating beams with sub-diffraction lobes. These structured beams are then used for high-resolution trapping and manipulation of nanometer-sized particles. The trapping potential provides unprecedented localization accuracy and stiffness, significantly exceeding those provided by standard diffraction-limited beams. Optical trapping: structuring super-oscillating beams Optical trapping with enhanced spatial accuracy and stiffness is possible using super-oscillating light beams that have been structured. Scientists from Tel-Aviv University in Israel and the Central University of Rajasthan in India sent a laser beam to a spatial light modulator (SLM) whose phase could be programmed and then focused the beam using a high-numerical-aperture microscope objective. By applying suitable phase profiles to the SLM, they were able to generate super-oscillating beams with Laguerre-Gauss, Hermite-Gauss and Airy profiles that had features that were smaller than half the wavelength of the light used — the first time that subdiffraction structures have been produced in non-Gaussian beams. By performing optical trapping with these structured, super-oscillating beams, the team was able to manipulate polystyrene nanoparticles with enhanced precision and force than when conventional, diffraction-limited Gaussian beams were used.
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These authors contributed equally to this work.
ISSN:2047-7538
2095-5545
2047-7538
DOI:10.1038/lsa.2017.50