ORCID Profile
0000-0002-4758-3528
Current Organisation
University of St Andrews
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Publisher: Optica Publishing Group
Date: 27-03-2008
DOI: 10.1364/OE.16.004991
Abstract: The confinement and controlled movement of metal nanoparticles and nanorods is an emergent area within optical micromanipulation. In this letter we experimentally realise a novel trapping geometry near the plasmon resonance using an annular light field possessing a helical phasefront that confines the nanoparticle to the vortex core (dark) region. We interpret our data with a theoretical framework based upon the Maxwell stress tensor formulation to elucidate the total forces upon nanometric particles near the particle plasmon resonance. Rotation of the particle due to orbital angular momentum transfer is observed. This geometry may have several advantages for advanced manipulation of metal nanoparticles.
Publisher: Springer Science and Business Media LLC
Date: 22-08-2017
DOI: 10.1038/S41598-017-08657-9
Abstract: The transversal profile of beams can always be defined as a superposition of orthogonal fields, such as optical eigenmodes. Here, we describe a generic method to separate the in idual components in a laser beam and map each mode onto its designated detector with low crosstalk. We demonstrate this with the decomposition into Laguerre-Gaussian beams and introduce a distribution over the integer numbers corresponding to the discrete orbital and radial momentum components of the light field. The method is based on determining an eigenmask filter transforming the incident optical eigenmodes to position eigenmodes enabling the detection of the state of the light field using single detectors while minimizing cross talk with respect to the set of filter masks considered.
Publisher: SPIE
Date: 09-10-2012
DOI: 10.1117/12.928482
Publisher: Optica Publishing Group
Date: 05-02-2009
DOI: 10.1364/OE.17.002375
Abstract: Common-path optical coherence tomography (CPOCT) is known to reduce group velocity dispersion and polarization mismatch between the reference and the s le arm as both arms share the same physical path. Existing implementations of CPOCT typically require one to incorporate an additional cover glass within the beam path of the s le arm to provide a reference signal. In this paper, we aim to further reduce this step by directly making use of the back-reflected signal, arising from a conical lens-tip fiber, as a reference signal. The conical lens, which is directly manufactured onto the optical fiber tip via a simple selective-chemical etching process, fulfils two functions acting as both the imaging lens and the self-aligning reference plane. We use a Fourier-domain OCT system to demonstrate the feasibility of this technique upon biological tissue. An in-fiber CPOCT technique may prove potentially useful in endoscopic OCT imaging.
Publisher: SPIE
Date: 19-08-2010
DOI: 10.1117/12.861474
Publisher: SPIE-Intl Soc Optical Eng
Date: 02-2010
DOI: 10.1117/1.3332850
Publisher: SPIE
Date: 28-08-2008
DOI: 10.1117/12.795085
Publisher: AIP
Date: 2011
DOI: 10.1063/1.3644220
Publisher: Optica Publishing Group
Date: 06-03-2008
DOI: 10.1364/OE.16.003712
Abstract: Near-field optical micromanipulation permits new possibilities for controlled motion of trapped objects. In this work, we report an original geometry for optically deflecting and sorting micro-objects employing a total internal reflection microscope system. A small beam of laser light is delivered off-axis through a total internal reflection objective which creates an elongated evanescent illumination of light at a glass/water interface. Asymmetrical gradient and scattering forces from this light field are seen to deflect and sort polystyrene microparticles within a fluid flow. The speed of the deflected objects is dependent upon their intrinsic properties. We present a finite element method to calculate the optical forces for the evanescent waves. The numerical simulations are in good qualitative agreement with the experimental observations and elucidate features of the particle trajectory. In the size range of 1 microm to 5 microm in diameter, polystyrene spheres were found to be guided on average 2.9 +/- 0.7 faster than silica spheres. The velocity increased by 3.0 +/- 0.5 microms(-1) per microm increase in diameter for polystyrene spheres and 0.7 +/- 0.2 microms(-1) per microm for silica. We employ this size dependence for performing passive optical sorting within a microfluidic chip and is demonstrated in the accompanying video.
Publisher: The Optical Society
Date: 06-07-2011
DOI: 10.1364/OE.19.013922
Publisher: American Chemical Society (ACS)
Date: 02-04-2012
DOI: 10.1021/NL204378R
Abstract: We present a generic technique allowing size-based all-optical sorting of gold nanoparticles. Optical forces acting on metallic nanoparticles are substantially enhanced when they are illuminated at a wavelength near the plasmon resonance, as determined by the particle's geometry. Exploiting these resonances, we realize sorting in a system of two counter-propagating evanescent waves, each at different wavelengths that selectively guide nanoparticles of different sizes in opposite directions. We validate this concept by demonstrating bidirectional sorting of gold nanoparticles of either 150 or 130 nm in diameter from those of 100 nm in diameter within a mixture.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Michael Mazilu.