Publications by Nicolas Le Thomas

3DPD: A photogrammetric pipeline for a PUSH frame stereo cameras

An innovative photogrammetric pipeline has been developed by INAF-Padova for the processing of the stereo images from the CaSSIS (Colour and Stereo Imaging System) (Thomas et al., 2014). CaSSIS is the multispectral stereo push frame camera on board ExoMars ...

PERGAMON-ELSEVIER SCIENCE LTD2021

Imaging of high-Q cavity optical modes by electron energy-loss microscopy

Romuald Houdré, Marco Cantoni, Nicolas Le Thomas, Cécile Hébert, Duncan Thomas Lindsay Alexander

We show a technique that images the intensity distribution and local state of polarization of the optical field of high-quality factor optical modes confined in dielectric planar photonic crystal nanocavities. Based on energy-loss spectroscopy of swift ele ...

Amer Physical Soc2013

Spectral heterogeneity on Phobos and Deimos: HiRISE observations and comparisons to Mars Pathfinder results

Nicolas Le Thomas, Anton Ivanov

The High-Resolution Imaging Science Experiment (HiRISE) onboard Mars Reconnaissance Orbiter (MRO) has been used to observe Phobos and Deimos at spatial scales of around 6 and 20 m/px, respectively. HiRISE (McEwen et al., JGR, 112, CitelD E05502, DOI: 10.10 ...

2011

Inhibited emission of electromagnetic modes confined in subwavelength cavities

Romuald Houdré, Nicolas Le Thomas

We experimentally demonstrate the active inhibition of subwavelength confined cavity modes emission and quality factor enhancement by controlling the cavity optical surrounding. The intrinsic radiation angular spectrum of modes confined in planar photonics ...

2011

Statistical analysis of subnanometer residual disorder in photonic crystal waveguides: Correlation between slow light properties and structural properties

Romuald Houdré, Nicolas Le Thomas, Hua Zhang, Zhaolu Diao

The authors present a statistical study of residual disorder in nominally identical planar photonic crystal waveguides operating in the slow light regime. The focus is on the role played by the subnanometer scaled residual disorder inherent to state-of-the ...

2011

Refractive Index Gas Sensing in a Hollow Photonic Crystal Cavity

Romuald Houdré, Nicolas Le Thomas, Hua Zhang, Jana Jágerská, Zhaolu Diao

We investigate hollow photonic crystal structures consisting in air-slot photonic crystal nanocavities. The high quality factor similar to 2.6x10(4) of such cavities along with a strong overlap between the resonant mode and the hollow core region allows fo ...

Ieee2011

Cathodoluminescence Mapping of Cherenkov-Radiation Generated Bloch-Modes in Planar Photonic Crystals by Fast Electrons

Romuald Houdré, Marco Cantoni, Simon Schneider, Nicolas Le Thomas, Cécile Hébert, Duncan Thomas Lindsay Alexander

Cambridge, Cambridge University Press2010

Refractive index sensing with an air-slot photonic crystal nanocavity

Romuald Houdré, Nicolas Le Thomas, Hua Zhang, Jana Jágerská, Zhaolu Diao

We investigate an air-slot photonic crystal cavity for high-precision refractive index sensing. The high quality factor ∼2:6 × 10^4 of the cavity, along with a strong overlap between the resonant mode and the hollow core region, allows us to achieve an exp ...

Optical Society of America2010

Fourier space imaging of light localization at a photonic band-edge located below the light cone

Romuald Houdré, Nicolas Le Thomas

We observe light localization in a two-dimensional geometry, induced by residual disorder at a photonic band edge located below the light cone. The combination of a spectrally selective illumination and a grating assisted k-space imaging technique allows u ...

2009

Radiation loss of photonic crystal coupled-cavity waveguides

Romuald Houdré, Nicolas Le Thomas, Hua Zhang, Jana Jágerská

We experimentally investigate the out-of-plane radiation losses of photonic crystal coupled-cavity waveguides. We observe a strong variation in the losses along the dispersion curve and show that such variation is closely linked with the specific far-field ...

American Institute of Physics2009

Experimental observation of slow mode dispersion in photonic crystal coupled-cavity waveguides

Romuald Houdré, Roel Baets, Nicolas Le Thomas, Vasily Zabelin, Jana Jágerská

We experimentally investigate the dispersion curve of an integrated silicon-on-insulator coupled-cavity waveguide in a photonic crystal environment using a technique based on far-field imaging. We show that a chain of eight coupled cavities of a moderate Q ...

Optical Society of America2009

Bloch mode excitation in two-dimensional photonic crystals imaged by Fourier optics

Romuald Houdré, Nicolas Le Thomas

Coupling into the Bloch modes of a two-dimensional photonic crystal (PhC) field is investigated by Fourier optics. The PhC was designed to operate in the second band above the air-light line, close to the autocollimation regime for TE polarization. The sam ...

2009

Hybrid inorganic-organic photonic devices

Romuald Houdré, Libero Zuppiroli, Rolando Ferrini, Laurent Balet, Nicolas Le Thomas, Pascale El-Kallassi

We present the infiltration of semiconductor photonic devices with organic materials. The infiltration procedures are described and validated. In particular, the optical properties of hybrid photonic crystal cavities are studied. ...

EOS2008

Coupling length of silicon-on-insulator directional couplers probed by Fourier-space imaging

Romuald Houdré, Nicolas Le Thomas, Jana Jágerská

We use a Fourier-space imaging technique relying on outcoupling grating probes to study the coupled mode interaction and dispersion properties of guided modes in silicon-on-insulator codirectional couplers. Our approach allows us to measure the mode splitt ...

American Institute of Physics2008

Influence of residual disorder on the anticrossing of Bloch modes probed in k space

Romuald Houdré, Nicolas Le Thomas, Vasily Zabelin

We retrieve the dispersion properties of photonic crystal waveguides near the band edge with high experimental accuracy. The dispersion diagram of the waveguide modes in the complex-valued plane is directly measured in the far ﬁeld by using a Fourier space ...

2008

Near-field mapping of quantum dot emission from single-photonic crystal cavity modes

Romuald Houdré, Massimo Gurioli, Laurent Balet, Nicolas Le Thomas

We directly investigate, by means of near-field spectroscopy, the spatial distribution of the optical cavity modes of 2D photonic crystal microcavities. Numerical simulations confirm that the photoluminescence maps of quantum dots embedded in the photonic ...

2008

Characterisation of photonic crystal and nanophotonics devices with Fourier optics

Romuald Houdré, Nicolas Le Thomas, Jana Jágerská

We report on the experimental investigation of the Floquet-Bloch modes propagation inside photonic crystal (PhC) structures as well as their emission from the structures with far-field optics. We demonstrate that far-field optical experiments can be used t ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2008

Towards a LED based on a photonic crystal nanocavity for single photon sources at telecom wavelength

Romuald Houdré, Blandine Alloing, Carl Zinoni, Laurent Balet, Nicolas Le Thomas

A fundamental step towards achieving an "on demand" single photon source would be the possibility of electrical pumping for a single QD and thus the integration of such a device in an opto-electronic circuit. In this work we describe the fabrication proces ...

Elsevier2008

Phase-sensitive Fourier space imaging of optical Bloch modes

Romuald Houdré, Nicolas Le Thomas

We present a phase-shifting holography method in k space that allows us to investigate the phase and amplitude of optical Bloch waves. The method is based on a Fourier space imaging technique combined with a Mach-Zehnder interferometer. Using a W3 photonic ...

2008

Optical tuning of planar photonic crystals infiltrated with organic molecules

Romuald Houdré, Libero Zuppiroli, Rolando Ferrini, Nicolas Le Thomas, Pascale El-Kallassi

The optical tuning of InP-based planar photonic crystals (PhCs) infiltrated with a photo-responsive liquid crystal system is presented. Photo-induced phase transitions of a liquid crystal blend doped with azobenzene molecules are used to tune the optical r ...

2007