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Dive into the research topics where Philippe Lalanne is active.

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Featured researches published by Philippe Lalanne.


Optics Express | 2013

Multi-resonant absorption in ultra-thin silicon solar cells with metallic nanowires

I. Massiot; Christophe Sauvan; Philippe Lalanne; Pere Roca i Cabarrocas; Jean-Luc Pelouard; Stéphane Collin

We propose a design to confine light absorption in flat and ultra-thin amorphous silicon solar cells with a one-dimensional silver grating embedded in the front window of the cell. We show numerically that multi-resonant light trapping is achieved in both TE and TM polarizations. Each resonance is analyzed in detail and modeled by Fabry-Perot resonances or guided modes via grating coupling. This approach is generalized to a complete amorphous silicon solar cell, with the additional degrees of freedom provided by the buffer layers. These results could guide the design of resonant structures for optimized ultra-thin solar cells.


Optics Express | 2014

Photonic molecules: tailoring the coupling strength and sign

S. Haddadi; Philippe Hamel; G. Beaudoin; I. Sagnes; Christophe Sauvan; Philippe Lalanne; Juan Ariel Levenson; A. M. Yacomotti

We demonstrate a large tuning of the coupling strength in Photonic Crystal molecules without changing the inter-cavity distance. The key element for the design is the photonic barrier engineering, where the potential barrier is formed by the air-holes in between the two cavities. This consists in changing the hole radius of the central row in the barrier. As a result we show, both numerically and experimentally, that the wavelength splitting in two evanescently-coupled Photonic Crystal L3 cavities (three holes missing in the ΓK direction of the underlying triangular lattice) can be continuously controlled up to 5× the initial value upon ∼ 30% of hole-size modification in the barrier. Moreover, the sign of the splitting can be reversed in such a way that the fundamental mode can be either the symmetric or the anti-symmetric one without altering neither the cavity geometry nor the inter-cavity distance. Coupling sign inversion is explained in the framework of a Fabry-Perot model with underlying propagating Bloch modes in coupled W1 waveguides.


Physical Review B | 2012

Measuring the spatial extent of individual localized photonic states

Marko Spasenović; Daryl M. Beggs; Philippe Lalanne; Thomas F. Krauss; L. Kuipers

Waves in disordered media can undergo multiple scattering, resulting in the formation of Anderson-localized states with an associated impeded wave transport. Anderson localization is a universal wave phenomenon, with manifestations in electron transport, 1 sound, 2 matter waves, 3,4 and light. 5,6 The spatial extent of localized states, or localization length, is of primary importance. For example, in systems of finite size, when this length is larger than the length of the sample, disorder has, on average, little effect on wave propagation. 7 Conversely, when this length is smaller than the sample length, strongly confined states with typical lengths shorter than the sample size are likely to occur and wave transport may be severely disrupted. The localization length is an ensemble-averaged quantity, typically obtained by averaging over frequency or many realizations of disorder. Here we show measurements of the spatial extent of individual localized photonic states for a single realization of disorder in a photonic crystal waveguide. To emphasize the difference between the ensemble-averaged localization length and the measured spatial extent of an individual localized state for a single optical frequency for a single realization of disorder, we will use the symbol Lind for the length that we measure. The spatial extent of localized photonic states has been measured before in a two-dimensional waveguide with embedded impurities. 8 In that waveguide the spectral width of the localized resonances is on the order of 10 nm. Close to the band edge of a photonic crystal waveguide, in the technologically important slow light region, localized resonances can have spectral widths on the order of 0.1 nm, associated with small mode volumes. Measuring spectrally narrow resonances with a near-field microscope is a challenge because the tip of the near-field microscope influences the local dielectric constant in its vicinity. This dielectric constant has a paramount influence on the spectral position of a resonance. We show a method to measure the length of a localized state in a photonic crystal waveguide by using the spectral shift to our advantage. We measure Lind with two different methods, a local perturbation method and one based on the inverse participation ratio (IPR), and show that the results are in quantitative agreement. We identify states for which Lind is smaller than the length of the waveguide and show that these states are not observable in traditional transmission measurements, although such states with their small volumes are arguably the most useful for applications in quantum computing and sensing. The idea that disorder in photonic crystals can be used


Advanced Optical Materials | 2013

Broadband and Efficient Diffraction

Céline Ribot; Mane-Si Laure Lee; Stéphane Collin; Shailendra Bansropun; Patrick Plouhinec; Didier Thénot; Simone Cassette; Brigitte Loiseaux; Philippe Lalanne

Surface topography dictates the deterministic functionality of diffraction by a surface. In order to maximize the efficiency with which a diffractive optical component, such as a grating or a diffractive lens, directs light into a chosen order of diffraction, it is necessary that it be blazed. The efficiency of most diffractive optical components reported so far varies with the wavelength, and blazing is achieved only at a specific nominal energy, the blaze wavelength. The existence of spurious light in undesirable orders represents a severe limitation that prevents using diffractive components in broadband systems. Here we experimentally demonstrate that broadband blazing over almost one octave can be achieved by combining advanced optical design strategies and artificial dielectric materials that offer dispersion chromatism much stronger than those of conventional bulk materials. The possibility of maintaining an efficient funneling of the energy into a specific order over a broad spectral range may empower advanced research to achieve greater control over the propagation of light, leading to more compact, efficient and versatile optical components.


arXiv: Optics | 2016

All-optical spatial light modulator for reconfigurable silicon photonic circuits

Roman Bruck; Kevin Vynck; Philippe Lalanne; Ben Mills; David J. Thomson; Goran Z. Mashanovich; Graham T. Reed; Otto L. Muskens

Reconfigurable photonic devices capable of routing the flow of light enable flexible integrated-optic circuits that are not hardwired but can be externally controlled. Analogous to free-space spatial light modulators, we demonstrate all-optical wavefront shaping in integrated silicon-on-insulator photonic devices by modifying the spatial refractive index profile of the device employing ultraviolet pulsed laser excitation. Applying appropriate excitation patterns grants us full control over the optical transfer function of telecommunication-wavelength light traveling through the device, thus allowing us to redefine its functionalities. As a proof of concept, we experimentally demonstrate the routing of light between the ports of a multimode interference power splitter with more than 97% total efficiency and negligible losses. Wavefront shaping in integrated photonic circuits provides a conceptually new approach toward achieving highly adaptable and field-programmable photonic circuits with applications in optical testing and data communication.


Science Advances | 2016

Single-plasmon interferences

Marie-Christine Dheur; Eloïse Devaux; Thomas W. Ebbesen; Jean-Claude Rodier; Jean-Paul Hugonin; Philippe Lalanne; Jean-Jacques Greffet; Gaétan Messin; François Marquier

The wave-particle duality of single surface plasmons is demonstrated using a plasmonic beam splitter on a flat gold device. Surface plasmon polaritons are electromagnetic waves coupled to collective electron oscillations propagating along metal-dielectric interfaces, exhibiting a bosonic character. Recent experiments involving surface plasmons guided by wires or stripes allowed the reproduction of quantum optics effects, such as antibunching with a single surface plasmon state, coalescence with a two-plasmon state, conservation of squeezing, or entanglement through plasmonic channels. We report the first direct demonstration of the wave-particle duality for a single surface plasmon freely propagating along a planar metal-air interface. We develop a platform that enables two complementary experiments, one revealing the particle behavior of the single-plasmon state through antibunching, and the other one where the interferences prove its wave nature. This result opens up new ways to exploit quantum conversion effects between different bosonic species as shown here with photons and polaritons.


Optics Express | 2014

Photonic crystal-based flat lens integrated on a Bragg mirror for high-Q external cavity low noise laser

M. S. Seghilani; M. Sellahi; M. Devautour; Philippe Lalanne; I. Sagnes; G. Beaudoin; Mikhael Myara; X. Lafosse; Luc Legratiet; J. Yang; A. Garnache

We demonstrate a high reflectivity (> 99%), low-loss (< 0.1%) and aberrations-free (2% of λ rms phase fluctuations) concave Bragg mirror (20mm radius of curvature) integrating a photonic crystal with engineered spherical phase and amplitude transfer functions, based on a III-V semiconductors flat photonics technology. This mirror design is of high interest for highly coherent high power stable external cavity semiconductor lasers, exhibiting very low noise. We design the photonic crystal for operation in the pass band. The approach incorporates spatial, spectral (filter bandwidth= 5nm) and polarization filtering capabilities. Thanks to the mirror, a compact single mode TEM(00) 2mm-long air gap high finesse (cold cavity Q-factor 10(6) - 10(7)) stable laser cavity is demonstrated with a GaAs-based quantum-wells 1/2-VCSEL gain structure at 1μm. Excellent laser performances are obtained in single frequency operation: low threshold density of 2kW/cm(2) with high differential efficiency (21%). And high spatial, temporal and polarization coherence: TEM(00) beam close to diffraction limit, linear light polarization (> 60dB), Side Mode Suppression Ratio > 46dB, relative intensity noise at quantum limit (< -150dB) in 1MHz-84GHz radio frequency range, and a theoretical linewidth fundamental limit at 10 Hz (Q-factor ∼ 3.10(13)).


Optics Express | 2013

Coupling light into a slow-light photonic-crystal waveguide from a free-space normally-incident beam

Philippe Hamel; Patricio Grinberg; Christophe Sauvan; Philippe Lalanne; Alexandre Baron; A. M. Yacomotti; I. Sagnes; Fabrice Raineri; Kamel Bencheikh; Juan Ariel Levenson

We present a coupler design allowing normally-incident light coupling from free-space into a monomode photonic crystal waveguide operating in the slow-light regime. Numerical three-dimensional calculations show that extraction efficiencies as high as 80% can be achieved for very large group indices up to 100. We demonstrate experimentally the device feasibility by coupling and extracting light from a photonic crystal waveguide over a large group-index range (from 10 to 60). The measurements are in good agreement with theoretical predictions. We also study numerically the impact of various geometrical parameters on the coupler performances.


arXiv: Optics | 2016

Light emission in nanogaps: overcoming quenching

Jianji Yang; Philippe Lalanne

Very large spontaneous-emission-rate enhancements (∼1000) are obtained for quantum emitters coupled with tiny plasmonic resonance, especially when emitters are placed in the mouth of nanogaps formed by metal nanoparticles that are nearly in contact. This fundamental effect of light emission at subwavelength scales is well documented and understood as resulting from the smallness of nanogap modes. In contrasts, it is much less obvious to figure out whether the radiation efficiency is high in these gaps, or if the emission is quenched by metal absorption especially for tiny gaps a few nanometers wide; the whole literature only contains scattered electromagnetic calculations on the subject, which suggest that absorption and quenching can be kept at a small level despite the emitter proximity to metal. Thus through analytical derivations in the limit of small gap thickness, it is our objective to clarify why quantum emitters in nanogap antennas offer good efficiencies, what are the circumstances in which high efficiency is obtained, and whether there exists an upper bound for the maximum efficiency achievable.


Journal of The Optical Society of America A-optics Image Science and Vision | 2014

Aperiodic-Fourier modal method for analysis of body-of-revolution photonic structures

Florian Bigourdan; Jean-Paul Hugonin; Philippe Lalanne

Modeling the field produced by a point-like dipole with an arbitrary location in the presence of a rotationally invariant nanostructure is an important issue in the context of designing nanoantennas. This is a challenging problem, as rotational symmetry is broken when introducing a noncentered dipole. Antennas larger than the wavelength are required for directivity, whereas the dipole-antenna distance is highly subwavelength, so there are two different length scales in the problem. In this paper, we introduce an original S-matrix approach based on an aperiodic-Fourier modal method. The potential of the technique is illustrated by considering three examples. We compare our results with a finite element technique.

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Jean-Paul Hugonin

Centre national de la recherche scientifique

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Kevin Vynck

University of Bordeaux

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Stéphane Collin

Centre national de la recherche scientifique

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J. Claudon

Technical University of Denmark

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Jean-Michel Gerard

Technical University of Denmark

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I. Sagnes

Centre national de la recherche scientifique

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G. Beaudoin

Centre national de la recherche scientifique

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Pierre Chavel

Centre national de la recherche scientifique

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