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1.
Opt Express ; 31(3): 4454-4464, 2023 Jan 30.
Article in English | MEDLINE | ID: mdl-36785413

ABSTRACT

We report on the synthesis of hybrid light emitting particles with a diameter ranging between 100 and 500 nm, consisting in a compact semiconductor CdSe/CdS/CdZnS nanocrystal aggregate encapsulated by a controlled nanometric size silica and gold layers. We first characterize the Purcell decay rate enhancement corresponding to the addition of the gold nanoshell as a function of the particle size and find a good agreement with the predictions of numerical simulations. Then, we show that the contribution corresponding to Förster resonance energy transfer is inhibited.

2.
Opt Express ; 30(25): 45093-45109, 2022 Dec 05.
Article in English | MEDLINE | ID: mdl-36522919

ABSTRACT

Coupling quantum emitters and nanostructures, in particular cold atoms and optical waveguides, has recently raised a large interest due to unprecedented possibilities of engineering light-matter interactions. In this work, we propose a new type of periodic dielectric waveguide that provides strong interactions between atoms and guided photons with an unusual dispersion. We design an asymmetric comb waveguide that supports a slow mode with a quartic (instead of quadratic) dispersion and an electric field that extends far into the air cladding for an optimal interaction with atoms. We compute the optical trapping potential formed with two guided modes at frequencies detuned from the atomic transition. We show that cold Rubidium atoms can be trapped as close as 100 nm from the structure in a 1.3-mK-deep potential well. For atoms trapped at this position, the emission into guided photons is largely favored, with a beta factor as high as 0.88 and a radiative decay rate into the slow mode 10 times larger than the free-space decay rate. These figures of merit are obtained at a moderately low group velocity of c/50.

3.
Phys Rev Lett ; 124(7): 073403, 2020 Feb 21.
Article in English | MEDLINE | ID: mdl-32142324

ABSTRACT

We study theoretically the scattering of light by an ensemble of N resonant atoms in a subwavelength volume. We consider the low intensity regime so that each atom responds linearly to the field. While N noninteracting atoms would scatter N^{2} more than a single atom, we find that N interacting atoms scatter less than a single atom near resonance. In addition, the scattered power presents strong fluctuations, either from one realization to another or when varying the excitation frequency. We analyze this counterintuitive behavior in terms of collective modes resulting from the light-induced dipole-dipole interactions. We find that for small samples and sufficiently large atom number, their properties are governed only by their volume.

4.
Phys Rev Lett ; 122(11): 113401, 2019 Mar 22.
Article in English | MEDLINE | ID: mdl-30951353

ABSTRACT

By measuring the transmission of near-resonant light through an atomic vapor confined in a nanocell we demonstrate a mesoscopic optical response arising from the nonlocality induced by the motion of atoms with a phase coherence length larger than the cell thickness. Whereas conventional dispersion theory-where the local atomic response is simply convolved by the Maxwell-Boltzmann velocity distribution-is unable to reproduce the measured spectra, a model including a nonlocal, size-dependent susceptibility is found to be in excellent agreement with the measurements. This result improves our understanding of light-matter interaction in the mesoscopic regime and has implications for applications where mesoscopic effects may degrade or enhance the performance of miniaturized atomic sensors.

5.
Phys Rev Lett ; 116(23): 233601, 2016 Jun 10.
Article in English | MEDLINE | ID: mdl-27341230

ABSTRACT

We measure the coherent scattering of light by a cloud of laser-cooled atoms with a size comparable to the wavelength of light. By interfering a laser beam tuned near an atomic resonance with the field scattered by the atoms, we observe a resonance with a redshift, a broadening, and a saturation of the extinction for increasing atom numbers. We attribute these features to enhanced light-induced dipole-dipole interactions in a cold, dense atomic ensemble that result in a failure of standard predictions such as the "cooperative Lamb shift". The description of the atomic cloud by a mean-field model based on the Lorentz-Lorenz formula that ignores scattering events where light is scattered recurrently by the same atom and by a microscopic discrete dipole model that incorporates these effects lead to progressively closer agreement with the observations, despite remaining differences.

6.
Opt Express ; 22(3): 2337-47, 2014 Feb 10.
Article in English | MEDLINE | ID: mdl-24663526

ABSTRACT

Quantum emitters such as NV-centers or quantum dots can be used as single-photon sources. To improve their performance, they can be coupled to microcavities or nano-antennas. Plasmonic antennas offer an appealing solution as they can be used with broadband emitters. When properly designed, these antennas funnel light into useful modes, increasing the emission rate and the collection of single-photons. Yet, their inherent metallic losses are responsible for very low radiative efficiencies. Here, we introduce a new design of directional, metallo-dielectric, optical antennas with a Purcell factor of 150, a total efficiency of 74% and a collection efficiency of emitted photons of 99%.

7.
Nano Lett ; 13(7): 3179-84, 2013 Jul 10.
Article in English | MEDLINE | ID: mdl-23777399

ABSTRACT

We demonstrate that confined Tamm plasmon modes can be advantageously exploited for the realization of new kind of metal/semiconductor lasers. Laser emission is demonstrated for Tamm structures with various diameters of the metallic disks which provide the confinement. A reduction of the threshold with the size is observed. The competition between the acceleration of the spontaneous emission and the increase of the losses leads to an optimal size, which is in good agreement with calculations.

8.
Nano Lett ; 13(4): 1516-21, 2013 Apr 10.
Article in English | MEDLINE | ID: mdl-23461679

ABSTRACT

We experimentally demonstrate the control of the spontaneous emission rate and the radiation pattern of colloidal quantum dots deterministically positioned in a plasmonic patch antenna. The antenna consists of a thin gold microdisk separated from a planar gold layer by a few tens of nanometers thick dielectric layer. The emitters are shown to radiate through the entire patch antenna in a highly directional and vertical radiation pattern. Strong acceleration of spontaneous emission is observed, depending on the antenna geometry. Considering the double dipole structure of the emitters, this corresponds to a Purcell factor up to 80 for dipoles perpendicular to the disk.


Subject(s)
Colloids/chemistry , Gold/chemistry , Quantum Dots , Equipment Design , Light , Nanostructures/chemistry , Nanotechnology , Optics and Photonics , Surface Plasmon Resonance
9.
Opt Express ; 21(3): 2563-80, 2013 Feb 11.
Article in English | MEDLINE | ID: mdl-23481714

ABSTRACT

We investigate the optical absorption in a thin Cu(In,Ga)Se(2) solar cell with a Lambertian white paint beneath a transparent back contact. Although this configuration has been proposed more than 30 years ago, it turns out that rigorous simulation of Maxwell's equations demand powerful numerical calculations. This type of approach is time consuming and does not provide a physical insight in the absorption mechanisms. Here, we use the radiative transfer equation to deal with multiple scattering of the diffuse part of the light. The collimated part is treated accounting for wave effects. Our model is in good agreement with optical measurements.


Subject(s)
Electric Power Supplies , Lenses , Metals/chemistry , Models, Theoretical , Solar Energy , Computer Simulation , Energy Transfer , Equipment Design , Equipment Failure Analysis , Scattering, Radiation
10.
Opt Express ; 20 Suppl 4: A530-44, 2012 Jul 02.
Article in English | MEDLINE | ID: mdl-22828622

ABSTRACT

We study the influence of the presence of an interface on the scattering by a Rayleigh scatterer. The influence of an interface on the spontaneous emission has been known for many years. Here, we study the influence on the extinction cross-section and absorption cross-section. We provide a detailed analysis of interference and near-field effects. We show that the presence of a Rayleigh scatterer may enhance the specular reflection or specular transmission under certain conditions. Finally, we analyze the enhancement of absorption in the bulk in the presence of a small scatterer.

11.
Phys Rev Lett ; 109(23): 237401, 2012 Dec 07.
Article in English | MEDLINE | ID: mdl-23368264

ABSTRACT

The electromagnetic modes of a GaAs quantum well between two AlGaAs barriers are studied. At the longitudinal optical phonon frequency, the system supports a phonon polariton mode confined in the thickness of the quantum well that we call epsilon-near-zero mode. This epsilon-near-zero mode can be resonantly excited through a grating resulting in a very large absorption localized in the single quantum well. We show that the reflectivity can be modulated by applying a voltage. This paves the way to a new class of active optoelectronic devices working in the midinfrared and far infrared at ambient temperature.

12.
Opt Express ; 19 Suppl 5: A1088-103, 2011 Sep 12.
Article in English | MEDLINE | ID: mdl-21935251

ABSTRACT

By combining stochastic electrodynamics and the Maxwell-Garnett description for effective media we study the radiative heat transfer between two nanoporous materials. We show that the heat flux can be significantly enhanced by air inclusions, which we explain by: (a) the presence of additional surface waves that give rise to supplementary channels for heat transfer throughout the gap, (b) an increase in the contribution given by the ordinary surface waves at resonance, (c) and the appearance of frustrated modes over a broad spectral range. We generalize the known expression for the nanoscale heat flux for anisotropic metamaterials.

13.
Phys Rev Lett ; 104(2): 026802, 2010 Jan 15.
Article in English | MEDLINE | ID: mdl-20366616

ABSTRACT

Single photon sources can greatly benefit from specially designed structures that modify the properties of the photon emitter. Dielectric cavities are often discussed, but they require a compromise between the spectral width and Purcell factor. In this Letter, we introduce plasmonic cavities as promising alternatives. We first study how the emitter couples with the modes of such structures. We then show how a patch antenna configuration simultaneously presents a large Purcell factor, collection efficiency, and spectral width.

14.
Phys Rev Lett ; 105(23): 234301, 2010 Dec 03.
Article in English | MEDLINE | ID: mdl-21231469

ABSTRACT

We present a formulation of the nanoscale radiative heat transfer using concepts of mesoscopic physics. We introduce the analog of the Sharvin conductance using the quantum of thermal conductance. The formalism provides a convenient framework to analyze the physics of radiative heat transfer at the nanoscale. Finally, we propose a radiative heat transfer experiment in the regime of quantized conductance.

15.
Opt Express ; 17(20): 17483-90, 2009 Sep 28.
Article in English | MEDLINE | ID: mdl-19907532

ABSTRACT

We present an explicit form of the surface plasmon propagator. Its form has the structure of a vectorial Huygens-Fresnel principle. The propagator appears to be a powerful tool to deal with diffraction, interference and focusing of surface plasmons. In contrast with the scalar approximation used so far, the vectorial propagator accounts for near-field and polarization effects. We illustrate the potential of the propagator by studying diffraction of surface plasmons by a slit and focusing of surface plasmons by a Fresnel lens.


Subject(s)
Light , Models, Theoretical , Refractometry/methods , Surface Plasmon Resonance/methods , Computer Simulation , Scattering, Radiation
16.
Opt Express ; 16(8): 5305-13, 2008 Apr 14.
Article in English | MEDLINE | ID: mdl-18542632

ABSTRACT

Absorption and emission of light due to the resonant excitation of surface waves on a grating is a well-known phenomenon. We report the first complete study of the influence of the role of angle and polarization on thermal emission by lamellar gratings. We derive the emitted Stokes vectors in any direction. We find that a source can be quasi isotropic from the point of view of the intensity but strongly anisotropic for polarized light. It follows that the degree of polarization can vary between 0 and 1, depending on directions.


Subject(s)
Computer-Aided Design , Models, Theoretical , Refractometry/instrumentation , Refractometry/methods , Computer Simulation , Equipment Design , Equipment Failure Analysis , Light , Scattering, Radiation , Temperature
17.
Phys Rev Lett ; 96(12): 123903, 2006 Mar 31.
Article in English | MEDLINE | ID: mdl-16605906

ABSTRACT

We show that a photonic crystal film can emit coherent thermal radiation. We demonstrate the key role of leaky waves existing at the air-photonic crystal interface. The frequency and direction of emission depend on the lattice parameters. This paves the way towards the design of coherent infrared antennas.

18.
Opt Lett ; 30(19): 2623-5, 2005 Oct 01.
Article in English | MEDLINE | ID: mdl-16208920

ABSTRACT

We report the design of a tungsten thermal source with extraordinarily high directivity in the near infrared, comparable to the directivity of a CO2 laser. This high directivity is the signature of the long-range correlation of the electromagnetic field in the source plane. This phenomenon is due to the resonant thermal excitation of surface-plasmon polaritons.

19.
Opt Lett ; 29(18): 2178-80, 2004 Sep 15.
Article in English | MEDLINE | ID: mdl-15460894

ABSTRACT

Resonant transmission through metallic films is observed when a periodic array of holes is drilled. This phenomenon has been attributed to surface plasmon polaritons. We study a similar system made of an array of slits in a SiC film supporting surface phonon polaritons. We find a resonant transmission in the infrared. The role of surface waves is analyzed. We find that surface waves are excited at resonance but are not a necessary condition to obtain a resonant transmission.

20.
Phys Rev Lett ; 92(21): 213903, 2004 May 28.
Article in English | MEDLINE | ID: mdl-15245283

ABSTRACT

We extend the theory of diffusing-wave spectroscopy using a random-walk approach and a numerical solution of the radiative transfer equation. The theory is not restricted to the diffusive regime and allows one to describe the crossover between the single-scattering and the diffusive regimes, which has been observed experimentally. It also predicts a lower bound of the scattered-field correlation time at long paths. This extended theory should have broad experimental applications in the field of imaging through biological tissues.

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