|Manuel Nieto Vesperinas|
SOME PROFESSIONAL ACTIVITIES
NEAR FIELD OPTICS AND PHOTONIC FORCE MICROSCOPY
The demonstration of levitation and trapping of small particles by light was established since more than twenty years ago. This has lead to recent studies of particle manipulation by the action of light. The resultant product has been the optical tweezer (OT) for handling microparticles and other biological microstructures suspended in solution, and the photonic force microscope (PFM) used as a transducer of the interaction potentials in colloids, or the binding forces in macromolecule arrays.
Our work consists of putting forward models of force action between particles, surfaces and light beams on illumination of these systems. In this way, we predict the magnitudes of forces and potentials through the action of illuminating beams. This makes it possible a monitoring of the signal provided by nano and microparticles in the OT and the PFM. The objective is twofold: on the one hand nanoparticles can be used as nanodetectors in the PFM, yielding better signals resembling surface topography than the near field optical microscope. On the other hand, the control of electromagnetic potential wells, created by light illumination, leads to a device of particle ensembles on substrates through light action.
Of particular relevance is the presence of morphological resonances in dense dielectric particles and plasmon polariton resonances in metallic microparticles and nanoparticles. The presence of particle eigenmodes excitation leads to dramatic enhancements of the interaction potentials, and thus of the binding forces and imaging signals.
In the last times, we have developed theories for optical forces on magnetodielectric particles and become interested in magnetic optics.
LIGHT PROPAGATION IN DISORDERED MEDIA
The phenomena of light localization in random media and photonic bandgaps in ordered structures have given rise to a series of interesting effects such as enhanced backscattering, long range correlations, new speckle statistics distributions, and photonic crystals. The influence of inhomogeneities and defects in the transmission properties of waveguides affects the wavefront and mode distribution, and thus has consequences for the transmission of information content of its degrees of freedom. This is characterized by the speckle pattern. Processing of these optical signals requires a detailed knowledge of the evolution of the speckle statistics on propagation. There already exist several analogies with electron transmission in nanowires. In this work, we analyze the transmittivity and reflectivity of surface disordered waveguides, the evolution of the speckle distribution, both in near field and far field (mode distribution), as the signal advances in the waveguide through the ballistic, diffusion and localization regimes.
DIFFUSE PHOTON DENSITY WAVES WITH SPECIAL EMPHASIS IN MEDICAL IMAGING
The study of light transport through strongly scattering media has recently received increased attention because of its applications to medical diagnosis. N particular, much research is motivated by the ability of optical radiation to diagnose tumors, brain oxigenation or blood clog formation. In most practical situations, the diffusion equation is suffciently accurate to describe visible or near-infrared radiation light transport within turbid media such as human tissues. A detailed analysis of these processes, both in the presence of interfaces between diffusive media, and at the separation of these from air or other non scattering regions, has been carried out. The resolution content and functional information of these waves has been analysed.
At present, we have put forward a direct scattering model that predicts the diffuse wavefront, in presence of resine and intralipid interfaces, of breasts with strange objects inside. The Green function or point source response of such a system has been successfully obtained. This allows the data inversion and the reconstruction of optical parameters of the hidden objects such as the scattering and absorption coefficients. A clinical application of this model, which is in progress, requires a subsequent development of a tomographic procedure in cylindrical geometries , a way to introduce specific contrast agents to enhance the signal scattered from the objects, and detailed clinical tests on the relationship between optical parameters and functional characteristics of tissue.
OPTICAL FORCES FROM DETERMINISTIC AND RANDOM WAVEFIELDS
We developed the first theories on optical forces on small particles at the nanoscale and the fundamentals and modelling of photonic force microscopy. In the last times we have developed theories for optical forces on magnetodielectric particles and become interested in magnetic optics and the magnetic effects of light in matter. This work conveying electric and magnetic dipoles induced by electromagnetic waves in small particles, has given rise to research on pulling forces towards sources without intensity spatial variations, as well as to studies on realistic Kerker’s conditions for zero backward or zero forward scattering cross sections on taking advantage of the magnetic partial wave excitation in IR and visible light suffering Mie scattering in semiconductor particles. These studies have shown the relationship to, and distinction from, Fano resonance anomalous scattering effects currently under study.
ANGULAR MOMENTUM OF LIGHT, AND ITS INTERACTION WITH CHIRAL AND ACHIRAL MATTER AT THE NANOSCALE
We develop a new theoretical framework on the effects from the transfer of spin and orbital angular momentum of twisted light to nanoparticles, either chiral or achiral, and magnetodielectric, i.e. with strong response to the magnetic vector of the illuminating wavefield.
We establish a new optical theorem which now applies to the conservation of electromagnetic helicity, - or chirality for time-harmonic wavefields -, as well as a rigorous formulation of the optical torque exerted by chiral beams on small scattering objects, whether particles or molecules. To this aim, we put forward the recoil component of the torque as the particle spins on its axis, as well as its orbital motion induced by the rotation of the illuminating beam wavefronts. We demonstrate how the contribution of the orbital angular momentum to the recoil torque, is a manifestation of the spin-orbit interaction on scattering of the incident wave by the particle.
The optical theorem for the electromagnetic chirality allows us to establish an enhancement factor for its extinction on scattering by a body in an inhomogeneous environment. This factor is a quantity that in future experiments should play a role analogous to the Purcell factor for energy extinction and emission. This leads us to put forward a unified formalism of circular dichroism based on the body induced electric and magnetic dipoles, which provides a means for tailoring scatterers that enhance either the extinguished chirality, (i.e. scattered plus converted), or the extinguished energy, (namely, scattered plus absorbed).
AND JOURNALS ISSUES
Scattering in Volumes and Surfaces
Scattering and Diffraction in Physical Optics
Optical Signal Processing, Multidimensional
Systems and Signal Processing
Optics at the Nanometer Scale: Imaging and
Storing with Photonic Near Fields
Wave Scattering from Rough Surfaces
and Related Phenomena. Part I, Waves in Random Media, Vol. 7,
No.3, (Institute of Physics Publishing, Bristol, 1997), 237 pags. (ISSN
0959-7174); Wave Scattering from Rough Surfaces and Related Phenomena.
Part II}, Waves in Random Media, Vol. 8, No.1, (Institute of
Physics Publishing, Bristol, 1998), 158 pags. (ISSN 0959-7174).
Nanoscale Science and Technology
Near Field Photonic Force
Research papers since
Field Distribution inside One-Dimensional
Random Photonic Lattices
Inhomogeneous Waves and Energy Localization
in Dielectric Superlattices
Reciprocity of Evanescent Electromagnetic
Field Theory for the Generalized Bidirectional
Reflectivity: Derivation of Helmholtz's Reciprocity Principle
and Kirchhoff's Law
Intensity Distribution of Transmitted Waves
in Surface Corrugated Waveguides
Determination of the Size and Shape of a
Sonoluminiscent Single Bubble: Theory on Angular Correlations of the Emitted
Statistical Distribution of Intensities of
Reflected Waves from Disordered Media
Scattering Integral Equations for Diffusive
Waves. Detection of Objects Buried in Diffusive Media in the Presence
Spatial Resolution of Diffuse Photon Density
Polarization Effects in the Scattering of
Electromagnetic Waves by an Object beneath a Random Rough Surface
Index Mismatch for Photon Density Waves both
at Flat and Rough Diffuse-Diffues Interfaces
Reflection and Transmission Coefficients
for Diffuse Photon Density Waves
Near field distributions of resonant modes
in small dielectric objects on flat surfaces
Reciprocity, unitarity and time-reversal
symmetry of the S-matrix of fields containing evanescent components
Coupled dipole method determination of the
electromagnetic force on a particle over a flat dielectric substrate
Spatial field distributions in the transition
from ballistic to diffusive transport in surface-corrugated waveguides
Defect Enhanced Resonances in Photonic Lattices
Light Amplification and Attenuation in Stratified
Structures with a Complex Refractive Index
Time-averaged total force on a dipolar sphere
in an electromagnetic field
Boundary conditions for light propagation
in diffusive media with non-scattering regions
Recovery of optical parameters in multiple
layered diffusive media: Theory
Finite size effects in the spatial distribution
of the intensity reflected from disordered media
Electromagnetic force on a metallic particle
in the presence of a dielectic surface
Effect of roughness in non-diffusive regions
within diffusive media
Resonant near field eigenmodes of nanocylinders
on flat surfaces under both homogenous and inhomogeneous lightwave excitation
3D optical tomography in the presence of
Resonant radiation pressure on neutral particles
in a waveguide
Optical binding of particles with or without
the presence of a flat dielectric surface
Fundamentals and model of photonic force
The Kirchhoff approximation for diffusive
Finite size effects on intensity correlations
in random media
Optical trapping and manipulation of nano-objects
with an apertureless probe
Modelling photonic force microscopy with
metallic particles under plasmon eigenmode excitation
Fast analytical approximation for arbitrary
geometries in diffuse optical tomography
Is there an experimental verification of
a negative index of refraction yet?
Left-handed materials do not make a perfect
Selective nanomanipulation using optical
Radiation pressure over dielectric and metallic
nanocylinders on surfaces: Polarization dependence and plasmon resonance
Losses for microwave transmission in metamaterials
for producing left-handed materials: The strip wires
Theory for tailoring sonic devices: Diffraction
dominates over refraction
Answer to Comment by J.B. Pendry on: Left-
Handed materials do not make a perfect lens
Transmission Measurements in Wedge-shaped
absorbing samples: An experiment for Observing negative refraction
Optical forces on small particles.
Attractive and repulsive nature and plasmon resonance condition
Theory for tailoring
sonic devices: Diffraction dominates over refraction
Transmission study of prisms and
slabs of lossy negative index media
Near field photonic forces
Problem of image superresolution with a negative-
refractive index slab
Reply to comment
by A. Hakanson et al. on: Theory for tailoring sonic devices: Diffraction dominates over
Photonic force spectroscopy on metallic and absorbing nanoparticles
Imaging of extended objects by a negative refractive index slab
Plasmon excitation in sets of nanoscale cilindres and spheres
Local field enhancement in an optical force metallic nanotrap: Application to songle-molecule spectroscopy
Tunable optical sorting and manipulation of nanoparticles via plasmon excitation
Enhanced optical forces between coupled resonant metal nanoparticles
Theory of electromagnetic wave transmission through metallic gratings of subwavelength slits
Imaging properties of photonic crystals
Optical forces near subwavelength aperturas in metal discs
Optical manipulation of plasmonic nanoparticles
Fully Valley-Polarized Electron Beams in Graphene
Experimetal two dimensional field mapping of total internal reflection lateral beam shift in a self-collimated photonic cristal
Resonance excitation and light concentration in sets of dielectric nanocylinders in front of a subwavelength aperture. Effects one extraordinary transmission.
Optical forces from an evanescent wave on a magnetodielectric small particle.
Angle-Suppressed Scattering and Optical Forces on Submicrometer Dielectric Particles.
Strong magnetic response of submicron Silicon particles in the infrared.
Nonconservative electric and magnetic optical forces on submicron dielectric particles.
Enhanced transmission through subwavelength apertures by excitation of particle localized plasmons and nanojets.
Electric and magnetic dipolar response of Germanium spheres: Interference effects, scattering anisotropy and optical forces.
Transmisstion of localized surface plasmons in sets of metallic nanocylinders in front of subwavelength slits.
Optical forces on cylinders near subwavelength slits: effects of extraordinary transmission and excitation of Mie resonances.
Photonic forces in the near field of statistically homogeneous fluctuating sources.
Optical forces on small particles from partially coherent light.
Composites of resonant dielectric rods: A test of their behavior as metamaterial refractive elements.
Magnetic and electric coherence in forward and backscattered electromagnetic waves by a single dielectric subwavelength sphere.
Optical forces on cylinders near subwavelength slits illuminated by a photonic nanojet.
Analysis of the Spectral Behavior of Localized Plasmon Resonances in the Near- and Far-Field Regimes.
On two definitions of the three-dimensional degree of polarization in the near field of statistically homogeneous partially coherent sources.
Tailoring photonic forces on a magnetodielectric nanoparticle with a fluctuating optical source.
Optical binding of cylinder photonic molecules in the near field of partially coherent fluctuating Gaussian Schell model sources: a coherent mode representation
Optical forces from evanescent Bessel beams, multiple reflections, and Kerker conditions in magnetodielectric spheres and cylinders
Material Independent Long Distance Pulling, Trapping, and Rotation of Fully Immersed Multiple Objects with a Single Optical Set-up.
Photonic band structure and eective medium properties of doubly-resonant core-shell metallo-dielectric nanowire arrays: low-loss, isotropic optical negative-index behavior.
Dielectric spheres with maximum forward scattering and zero backscattering: a search for their material composition.
Optical torque on small bi-isotropic particles.
A unified theory correcting Einstein-Laub’s electrodynamics solves dilemmas in the electromagnetic stress tensors and photon momenta.
Optical theorem for the conservation of electromagnetic helicity: Its significance for molecular energy transfer and enantiomeric discrimination by circular dichroism.
The optical torque: Electromagnetic spin and orbital angular momenta conservation laws and their significance.
Controlling lateral Fano interference optical force with Au-Ge2Sb2Te5 hybrid nanostructure.
Chiral optical fields: a unified formulation of helicity scattered > from particles and dichroism enhancement.
Non-zero helicity extinction in light scattered from achiral (or > chiral) small particles located at points of null incident helicity density.
Chiral scatterers designed by Bayesian optimization.
Optical Manipulation from Microscale to Nanoscale: Fundamentals, Advances, and Prospects.
Self-induced back-action optical pulling force.
Time-Harmonic Optical Chirality for Classfication of Scatterers
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