Petru Ghenuche
Centre national de la recherche scientifique
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Publication
Featured researches published by Petru Ghenuche.
Nano Letters | 2009
Maurizio Righini; Petru Ghenuche; Sudhir Cherukulappurath; Viktor Myroshnychenko; F. J. García de Abajo; Romain Quidant
Immobilizing individual living microorganisms at designated positions in space is important to study their metabolism and to initiate an in situ scrutiny of the complexity of life at the nanoscale. While optical tweezers enable the trapping of large cells at the focus of a laser beam, they face difficulties in maintaining them steady and can become invasive and produce substantial damage that prevents preserving the organisms intact for sufficient time to be studied. Here we demonstrate a novel optical trapping scheme that allows us to hold living Escherichia coli bacteria for several hours using moderate light intensities. We pattern metallic nanoantennas on a glass substrate to produce strong light intensity gradients responsible for the trapping mechanism. Several individual bacteria are trapped simultaneously with their orientation fixed by the asymmetry of the antennas. This unprecedented immobilization of bacteria opens an avenue toward observing nanoscopic processes associated with cell metabolism, as well as the response of individual live microorganisms to external stimuli, much in the same way as pluricellular organisms are studied in biology.
Nano Letters | 2011
Andrea Cattoni; Petru Ghenuche; Anne-Marie Haghiri-Gosnet; D. Decanini; Jing Chen; Jean-Luc Pelouard; Stéphane Collin
Arrays of plasmonic nanocavities with very low volumes, down to λ(3)/1000, have been fabricated by soft UV nanoimprint lithography. Nearly perfect omnidirectional absorption (3-70°) is demonstrated for the fundamental mode of the cavity (λ ≃ 1.15 μm). The second-order mode exhibits a sharper resonance with strong angular dependence and total optical absorption when the critical coupling condition is fulfilled (45-50°, λ ≃ 750 nm). It leads to high refractive index sensitivity (405 nm/RIU) and figure of merit (∼21) and offers new perspectives for efficient biosensing experiments in ultralow volumes.
Applied Physics Letters | 2011
Patrick Bouchon; Fabrice Pardo; L. Ferlazzo; Petru Ghenuche; Gulnar Dagher; Christophe Dupuis; Nathalie Bardou; Riad Haïdar; Jean-Luc Pelouard
We demonstrate the total extinction of the reflectivity for a transverse magnetic polarized wave on a gold surface etched on 6% of its area by both narrow (150 nm) and deep (2 μm) grooves. These high aspect ratio metallic grooves were fabricated using a mold cast technique based on an electrolytic growth of gold. They exhibit two resonance peaks corresponding to the first and second cavity modes inside the grooves. We also evidence the incidence-invariance of their spectral response, which undoubtedly shows the localized nature of the resonances. These experimental results confirm the prediction of total funneling of light in very narrow grooves.
Optics Letters | 2011
Emilie Sakat; Grégory Vincent; Petru Ghenuche; Nathalie Bardou; Stéphane Collin; Fabrice Pardo; Jean-Luc Pelouard; Riad Haïdar
We present the experimental study of a free-standing metallic guided-mode resonant structure, for bandpass filtering applications in the mid-IR wavelength range. Structure consists of a subwavelength gold grating with narrow slits deposited on a silicon nitride membrane. High optical transmission is measured with up to 78% transmission at resonance. Angularly resolved spectra are presented revealing Fano-type resonance.
Physical Review Letters | 2012
Petru Ghenuche; Grégory Vincent; Marine Laroche; Nathalie Bardou; Riad Haïdar; Jean-Luc Pelouard; Stéphane Collin
We demonstrate that almost 100% of incident photons can interact with a monolayer of scatterers in a symmetrical environment. Nearly perfect optical extinction through free-standing transparent nanorod arrays has been measured. The sharp spectral opacity window, in the form of a characteristic Fano resonance, arises from the coherent multiple scattering in the array. In addition, we show that nanorods made of absorbing material exhibit a 25-fold absorption enhancement per unit volume compared to unstructured thin film. These results open new perspectives for light management in high-Q, low volume dielectric nanostructures, with potential applications in optical systems, spectroscopy, and optomechanics.
Optics Letters | 2005
Petru Ghenuche; Romain Quidant; Gonçal Badenes
The dramatic field enhancement at the extremity of finite chains of strongly coupled gold nanoparticles illuminated under total internal reflection is investigated numerically. We demonstrate that high enhancement factors can be achieved by exploiting the in-plane forward scattering of the particles, with geometries achievable by state-of-the-art lithographic techniques.
Wiley Interdisciplinary Reviews-nanomedicine and Nanobiotechnology | 2014
Deep Punj; Petru Ghenuche; Satish Babu Moparthi; Juan de Torres; Victor Grigoriev; Hervé Rigneault; Jérôme Wenger
Single-molecule approaches to biology offer a powerful new vision to elucidate the mechanisms that underpin the functioning of living cells. However, conventional optical single molecule spectroscopy techniques such as Förster fluorescence resonance energy transfer (FRET) or fluorescence correlation spectroscopy (FCS) are limited by diffraction to the nanomolar concentration range, far below the physiological micromolar concentration range where most biological reaction occur. To breach the diffraction limit, zero-mode waveguides (ZMW) and plasmonic antennas exploit the surface plasmon resonances to confine and enhance light down to the nanometer scale. The ability of plasmonics to achieve extreme light concentration unlocks an enormous potential to enhance fluorescence detection, FRET, and FCS. Single molecule spectroscopy techniques greatly benefit from ZMW and plasmonic antennas to enter a new dimension of molecular concentration reaching physiological conditions. The application of nano-optics to biological problems with FRET and FCS is an emerging and exciting field, and is promising to reveal new insights on biological functions and dynamics.
Optics Letters | 2012
Petru Ghenuche; S. Rammler; Nicolas Y. Joly; M. Scharrer; Michael H. Frosz; Jérôme Wenger; Philip St. J. Russell; Hervé Rigneault
We demonstrate the use of a large-pitch Kagome-lattice hollow-core photonic crystal fiber probe for Raman spectroscopy. The large transmission bandwidth of the fiber enables both the excitation and Raman beams to be transmitted through the same fiber. As the excitation beam is mainly transmitted through air inside the hollow core, the silica luminescence background is reduced by over 2 orders of magnitude as compared to standard silica fiber probes, removing the need for fiber background subtraction.
Optics Express | 2012
Emilie Sakat; Grégory Vincent; Petru Ghenuche; Nathalie Bardou; Christophe Dupuis; Stéphane Collin; Fabrice Pardo; Riad Haïdar; Jean-Luc Pelouard
We study experimentally and theoretically band-pass filters based on guided-mode resonances in free-standing metal-dielectric structures with subwavelength gratings. A variety of filters are obtained: polarizing filters with 1D gratings, and unpolarized or selective filters with 2D gratings, which are shown to behave as two crossed-1D structures. In either case, a high transmission (up to ≈ 79 %) is demonstrated, which represents an eight-fold enhancement compared to the geometrical transmission of the grating. We also show that the angular sensitivity strongly depends on the rotation axis of the sample. This behavior is explained with a detailed description of the guided-mode transmission mechanism.
Nano Letters | 2015
Petru Ghenuche; Mathieu Mivelle; Juan de Torres; Satish Babu Moparthi; Hervé Rigneault; Niek F. van Hulst; Maria F. Garcia-Parajo; Jérôme Wenger
Förster resonance energy transfer (FRET) is widely applied in chemistry, biology, and nanosciences to assess distances on sub-10 nm scale. Extending the range and applicability of FRET requires enhancement of the fluorescence energy transfer at a spatial scale comparable to the donor-acceptor distances. Plasmonic nanoantennas are ideal to concentrate optical fields at a nanoscale fully matching the FRET distance range. Here, we present a resonant aluminum nanogap antenna tailored to enhance single molecule FRET. A 20 nm gap confines light into a nanoscale volume, providing a field gradient on the scale of the donor-acceptor distance, a large 10-fold increase in the local density of optical states, and strong intensity enhancement. With our dedicated design, we obtain 20-fold enhancement on the fluorescence emission of donor and acceptor dyes, and most importantly up to 5-fold enhancement of the FRET rate for donor-acceptor separations of 10 nm. We also provide a thorough framework of the fluorescence photophysics occurring in the nanoscale gap volume. The presented enhancement of energy transfer flow at the nanoscale opens a yet unexplored facet of the various advantages of optical nanoantennas and provides a new strategy toward biological applications of single molecule FRET at micromolar concentrations.