PUBLICATIONS

Hyperspectral Widefield

• 2012 Modified fuzzy c-means applied to a Bragg grating-based spectral imager for material clustering

  Aida Rodríguez ; Juan Luis Nieves ; Eva Valero ; Estíbaliz Garrote ; Javier Hernández-Andrés ; Javier Romero

  We have modified the Fuzzy C-Means algorithm for an application related to segmentation of hyperspectral images. Classical fuzzy c-means algorithm uses Euclidean distance for computing sample membership to each cluster. We have introduced a different distance metric, Spectral Similarity Value (SSV), in order to have a more convenient similarity measure for reflectance information. SSV distance metric considers both magnitude difference (by the use of Euclidean distance) and spectral shape (by the use of Pearson correlation). Experiments confirmed that the introduction of this metric improves the quality of hyperspectral image segmentation, creating spectrally more dense clusters and increasing the number of correctly classified pixels.

  Full article here.

• 2009 Evaluation of unmixing methods for the separation of Quantum Dot sources

  Fogel, P.; Gobinet, C.; Young, S.S.; Zugaj, D.

  Full article here.

• 2006 The imaging Bragg Tunable Filter: a new path to integral field spectroscopy and narrow band imaging

  Sébastien Blais-Ouellette a, Olivier Daigle a, b, Keith Taylor c

  a Photon etc

  b Université de Montréal

  c California Institute of Technology

  ABSTRACT

  An entirely new type of imaging tunable filter has been developed by Photon etc. and the California Institute of Technology. The Volume Bragg Grating based device is able to select a single wavelength for each pixel in a full camera field. The demonstration tabletop prototype was able to select images with a 2 nm bandwidth from 400 to 750 nm. Data cubes were produced through a wavelength scan from which a spectrum per pixel can be extracted. The prototype showed no image distortion, a very stable instrument profile, and high efficiency. The compact and robust tunable filter can operate from 350 nm to 2.5 mm with bandwidths from 3 Ǻ to 200 nm, showing a great potential for both ground based and space astronomy.

  Keywords: Astronomical instrumentation, Tunable filter, Volume Bragg Grating, Integral field spectroscopy, Narrowband imaging, Fabry-Perot, VBG, VPH, VHG

  spie_ibtf_2006.pdf

Tunable Source & Filter

• 2013 Spectral properties of ultra-broadband entangled photons generated from chirped-MgSLT crystal towards monocycle entanglement generation

  Akira Tanaka ; Ryo Okamoto ; Hwan Hong Lim ; Shanthi Subashchandran ; Masayuki Okano ; Labao Zhang ; Lin Kang ; Jian Chen ; Peiheng Wu ; Toru Hirohata ; Sunao Kurimura ; Shigeki Takeuchi.

  Compressing the temporal correlation of two photons to the monocycle regime (3.56 fs, center wavelength: 1064 nm) is expected to open up new perspectives in quantum metrology, allowing applications such as submicron quantum optical coherence tomography and novel nonlinear optical experiments. To achieve this, the two-photon state must essentially be ultra-broadband in the frequency domain and ultra-short in the time domain. Here, we report the successful generation of such ultra-broadband, frequency-correlated two-photon states via type-0, cw-pumped (532 nm) spontaneous parametric down conversion using four PPMgSLT crystals with different chirp rates of their poling periods. For the collinear condition, single-photon spectra are detected using a Si-CCD and an InGaAs photodiode array with a monochromator, while for a noncollinear condition, an NbN meander-type superconducting single photon detector (SNSPD) and an InP/GaAs photomultiplier tube (PMT) with a laser line Bragg tunable bandpass filter are used. The broadband sensitivity of the SNSPD and PMT in the near-infrared wavelength range enable singleshot observations with a maximum bandwidth of 820 nm among the four samples. Such spectra can in principle achieve a temporal correlation as short as 1.2 cycles (4.4 fs) with the use of appropriate phase compensation, which can be measured using the sum-frequency signal. We also discuss several detection strategies for measuring coincidence counts in the presence of wavelength-dependent optical elements as a step towards frequency correlation measurements. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

  Full article here.

• 2013 Measurements of the Population Lifetime of D Band and G' Band Phonons in Single-Walled Carbon Nanotubes

   

  John M. Nesbitt and David C. Smith, School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, United Kingdom

   

  We report time-resolved incoherent anti-Stokes Raman scattering measurements of the dynamics of the D and G′ bands in single-walled carbon nanotubes at excitation energies of 1.51 and 1.63 eV over the temperature range 4–330 K. The measurements indicate that the population lifetimes (1 ps) of the phonons responsible for the D band are dependent on nanotube type. The temperature dependencies are consistent with anharmonic decay of the phonons into one low (<190 cm–1) and one high energy phonon.

   

  Full article here.

   

  Research group.
• 2012 Multiband sensor using thick holographic gratings for sulfur detection by laser-induced breakdown spectroscopy

   

  ABSTRACT

  Daniel Gagnon, Simon Lessard, Marc Verhaegen, Patrick Mutchmore, Paul Bouchard, François R. Doucet, and Mohamad Sabsabi

  Detection of sulfur by optical emission spectroscopy generally presents some difficulties because the strongest lines are in the vacuum UV below 185 nm and therefore are readily absorbed by oxygen molecules in air. A novel concept for a low-cost and efficient system to detect sulfur using near-IR bands by laser-induced breakdown spectroscopy is here proposed. This concept is based on customized thick holographic gratings as spectral filtering elements. The signal integration and the temporal synchronization are performed using built-in custom electronics that amplify and integrate or trigger photodiode output signals. In this work, we use the near-IR lines at 921.287 nm and a background reference at 900 nm. Preliminary results show a limit of detection comparable to that of a conventional high-end system.

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• 2011 Hybrid Semiconductor-Atomic Interface: Slowing Down Single Photons From a Quantum Dot

  ABSTRACT

  N. Akopian, L. Wang, A. Rastelli, O. G. Schmidt & V. Zwiller  

  Hybrid interfaces between semiconductor quantum dots and atomic systems could be of potential fundamental and technological interest, because they can combine the advantages of both constituents. Semiconductor quantum dots are tunable and deterministic sources of single¹ and entangled photons². Atomic vapours are widely used as slow-light media^3, 4 and quantum memories^5, 6. Merging both systems could enable the storage of quantum dot emission—an important step towards the implementation of quantum memories and quantum repeaters⁷. Here, we show a hybrid semiconductor–atomic interface for slowing down single photons emitted from a single quantum dot. We use a double absorption resonance⁴ in rubidium vapour to create a slow-light medium in which a single photon is stored for 15 times its temporal width. Our result is the first demonstration of non-classical light storage, where single photons are generated on demand from a semiconductor source.

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• 2011 Micrometer axial resolution OCT for corneal imaging

   

  Rahul Yadav, Kye-Sung Lee, Jannick P. Rolland, James M. Zavislan, James V. Aquavella, and Geunyoung Yoon

  ABSTRACT

  An optical coherence tomography (OCT) for high axial resolution corneal imaging is presented. The system uses 375 nm bandwidth (625 to 1000 nm) from a broadband supercontinuum light source. The system was developed in free space to minimize image quality degradation due to dispersion. A custom-designed spectrometer based on a Czerny Turner configuration was implemented to achieve an imaging depth of 1 mm. Experimentally measured axial resolution was 1.1 μm in corneal tissue and had a good agreement with the theoretically calculated resolution from the envelope of the spectral interference fringes. In vivo imaging was carried out and thin corneal layers such as the tear film and the Bowman’s layer were quantified in normal, keratoconus, and contact lens wearing eyes, indicating the system’s suitability for several ophthalmic applications.

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• 2011 Blue-Extended Sub-Nanosecond Supercontinuum Generation in Simply Designed Nonlinear Microstructured Optical Fibers

   

  Debashri Ghosh, Samudra Roy, Mrinmay Pal, Philippe Leproux, Pierre Viale, Vincent Tombelaine, and Shyamal K. Bhadra

  ABSTRACT

  We report experimentally observed extreme blue-enhanced supercontinuum (SC) generation down to 372 nm wavelength in simply designed and easily fabricated nonlinear microstructured optical fibers (MOFs). Three different MOFs of various core sizes and dispersion profiles are fabricated in order to optimize the parameters for achieving deeper blue components by group-index matching. The physical mechanism involved in the generation of extreme blue component is explained along with other nonlinear processes participating in the spectral broadening. We also explore the extent of applicability of the group-index matching technique for obtaining blue-enhanced SC and finally optimize the location of the zero dispersion wavelength (ZDW) with respect to the pump wavelength to achieve the maximum blue shift. 

  © 2011 IEEE

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• 2010 Single-Walled Carbon Nanotube Thermopile For Broadband Light Detection

   

  Benoit C. St-Antoine †§, David Ménard *†§, and Richard Martel *†‡

  † Regroupement Québécois sur les Matériaux de Pointe (RQMP), Montréal QC, Canada

  ‡ Département de Chimie, Université de Montréal, Montréal QC H3T 1J4, Canada

  § Département de Génie Physique, École Polytechnique de Montréal, Montréal QC H3C 3A7, Canada

   

  We designed a thermopile based on a PN doping profile engineered in a suspended film of single-walled carbon nanotubes (SWNTs). Using estimates of the film local Seebeck coefficients, the SWNT thermopile was optimized in situ through depositions of potassium dopants. The overall performances of the thermopile were found to be comparable to state-of-the-art SWNT bolometers. The device is characterized at room temperature by a time response of 36 ms, typical of thermal detectors, and an optimum spectral detectivity of 2 × 106 cm Hz1/2/W in the visible and near-infrared. This paper presents the first thermopile made of a suspended SWNT film and paves the way to new applications such as broadband light (including THz) detection and thermoelectric power generation.

   

  Full article here.
• 2010 Thin Films Magneto-Optic Characterization with Supercontinuum Tunable Source

  1 T. R. Zaman, X. Guo and R. J. Ram, 

  Semiconductor Waveguide Isolators, 

  Journal of Lightwave Technology, 26, 2, (2008)

   

  2 G. Monette, C. Lacroix, S. Lambert-Milot, V. Boucher, 

  D. Ménard and S. Francoeur, Giant magneto-optical Faraday effect in GaP epilayers containing MnP magnetic nanoclusters, 

  Journal of Applied Physics, 107, 9, (2010)

   

  ABSTRACT

  Magneto-optical (MO) effects are used either as tools for probing the magnetization reversal characteristics of a wide range of sample types, or as an effective way to modify the polarization of light via induced magnetization state in samples. In transparent samples, the Faraday effect (rotation of the polarization of light proportional to the magnetic induction field and optical path in the medium) can be used to elaborate Faraday rotators, a key element in the design of optical isolators (1). Along with other MO effects such as Kerr measurements, they provide a non-destructive probe for in-situ measurements of samples, such as thin films.

  Read the application note

   

• 2010 Structured-Core GeO -Doped Photonic-Crystal Fibers for Parametric and Supercontinuum Generation

   

  Labruyère, A.; Leproux, P.; Couderc, V.; Tombelaine, V.; Kobelke, J.; Schuster, K.; Bartelt, H.; Hilaire, S.; Huss, G.; Mélin, G.; XLIM Res. Inst., Univ. of Limoges, Limoges, France

  ABSTRACT

  We demonstrate efficient broadband four-wave-mixing (FWM) generation at the particular frequency detuning of ~150 THz from a 1064-nm sub-nanosecond laser pump in innovative structured-core germanium-oxide (GeO₂)-doped photonic crystal fibers (PCFs). Remarkably, the latter PCF has a small-diameter highly concentrated germanium rod in the core center that enables fine tuning of the FWM wavelengths. The generated anti-Stokes radiation at ~700 nm is subsequently used as secondary pump for generating a bright visible supercontinuum in the fundamental mode from 370 nm to beyond 1750 nm, when splicing the GeO₂-doped PCF to a pure-silica PCF, whose zero-dispersion wavelength is set in-between the pump and anti-Stokes wavelengths, consistently with the standard dual-wavelength pumping scheme.

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• 2010 Tuning Single GaAs Quantum Dots in Resonance with a Rubidium Vapor

  ABSTRACT

  N. Akopian¹, U. Perinetti¹, L. Wang^2,3, A. Rastelli², O. G. Schmidt², and V. Zwiller¹
  1. Quantum Transport, Kavli Institute of Nanoscience, TU Delft, 2628CJ Delft, The Netherlands
  2. Max Planck Institute for Solid State Research, Heisenbergstr. 1, D-70569 Stuttgart, Germany
  3. Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, 01069 Dresden, Germany  

  We study single GaAs quantum dots with optical transitions that can be brought into resonance with the widely used D₂ transitions of rubidium atoms. We achieve resonance by Zeeman or Stark shifting the quantum dot levels. We discuss an energy stabilization scheme based on the absorption of quantum dot photoluminescence in a rubidium vapor. This offers a scalable means to counteract slow spectral diffusion in quantum dots.

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• 2009 Nonlinear photonic crystal fiber with a structured multi-component glass core for four-wave mixing and supercontinuum generation

   

  Vincent Tombelaine, Alexis Labruyère, Jens Kobelke, Kay Schuster, Volker Reichel, Philippe Leproux, Vincent Couderc, Raphaël Jamier, and Hartmut Bartelt

  ABSTRACT

  We report about a new type of nonlinear photonic crystal fibers allowing broadband four-wave mixing and supercontinuum generation. The microstructured optical fiber has a structured core consisting of a rod of highly nonlinear glass material inserted in a silica tube. This particular structure enables four wave mixing processes with very large frequency detuning (>135 THz), which permitted the generation of a wide supercontinuum spectrum extending over 1650 nm after 2.15 m of propagation length. The comparison with results obtained from germanium-doped holey fibers confirms the important role of the rod material properties regarding nonlinear process and dispersion. 

  © 2009 OSA

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• 2009 The Gemini Planet Imager coronagraph testbed

  Rémi Soummer
  Space Telescope Science Institute (USA) and American Museum of Natural History (USA)

  Anand Sivaramakrishnan, Ben R. Oppenheimer, Robin Roberts,Douglas Brenner, Emily Griffiths, and Jacob Mey
  American Museum of Natural History (USA)

  Alexis Carlotti
  Univ. de Nice Sophia Antipolis (France)

  Laurent Pueyo and Kent Wallace
  Jet Propulsion Lab. (USA)

  Bruce Macintosh, Brian Bauman, and David Palmer
  Lawrence Livermore National Lab. (USA)

  Les Saddlemyer, Darren Erickson, Kris Caputa, and Christian Marois Herzberg
  Institute of Astrophysics, National Research Council Canada (Canada)

  Christophe Dorrer
  Aktiwave LLC (USA)

   

  ABSTRACT

  The Gemini Planet Imager (GPI) is a new facility instrument to be commissioned at the 8-m Gemini South telescope in early 2011. It combines of several subsystems including a 1500 subaperture Extreme Adaptive Optics system, an Apodized Pupil Lyot Coronagraph, a near-infrared high-accuracy interferometric wavefront sensor, and an Integral Field Unit Spectrograph, which serves as the science instrument. GPI's main scientific goal is to detect and characterize relatively young (<2GYr), self luminous planets with planet-star brightness ratios of ≤ 10^-7 in the near infrared. Here we present an overview of the coronagraph subsystem, which includes a pupil apodization, a hard-edged focal plane mask and a Lyot stop. We discuss designs optimization, masks fabrication and testing. We describe a near infrared testbed, which achieved broadband contrast (H-band) below 10^-6 at separations > 5λ/D, without active wavefront control (no deformable mirror). We use Fresnel propagation modeling to analyze the testbed results.

  © 2009 COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

  Access article here

• 2005 Ultra wide band supercontinuum generation in air-silica holey fibers by SHG-induced modulation instabilities

   

  Vincent Tombelaine, Christelle Lesvigne, Philippe Leproux, Ludovic Grossard, Vincent Couderc, Jean-Louis Auguste, Jean-Marc Blondy, Guillaume Huss, and Paul-Henri Pioger

  ABSTRACT

  Second harmonic generation in an air-silica microstructured optical fiber pumped by subnanosecond pulses is used in order to initiate modulation instability processes in normal and anomalous dispersion regimes. This allows us to generate an ultra wide and flat supercontinuum (350-1750 nm), covering the entire transparency window of silica and exhibiting a singlemode transverse profile in visible range. 

  © 2005 Optical Society of America

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• 2004 White-light supercontinuum generation in normally dispersive optical fiber using original multi-wavelength pumping system

   

  Pierre-Alain Champert, Vincent Couderc, Philippe Leproux, Sébastien Février, Vincent Tombelaine, Laurent Labonté, Philippe Roy, Claude Froehly, and Philippe Nérin

  ABSTRACT

  We report on the experimental demonstration of a white-light supercontinuum generation in normally dispersive singlemode air-silica microstructured fiber. We demonstrate that the simultaneous excitation of the microstuctured fiber in its normal and anomalous dispersion regimes using the fundamental and second harmonic signals of a passively Q-switched microchip laser leads to a homogeneous supercontinuum in the visible range. This pumping scheme allows the suppression of the cascaded Raman effect predominance in favor of an efficient spectrum broadening induced by parametric phenomena. A flat supercontinuum extended from 400 to 700 nm is achieved. 

  © 2004 Optical Society of America

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SWIR Camera

• 2009 Extreme Faint Flux Imaging with an EMCCD

  Olivier Daigle^1,2,3, Claude Carignan^1,4, Jean-Luc Gach², Christian Guillaume⁵, Simon Lessard³, Charles-Anthony Fortin³ et Sébastien Blais-Ouellette³

  1 Laboratoire d’Astrophysique Expérimentale, Département de Physique, Université de Montréal.

  2 Aix-Marseille Université—CNRS—Laboratoire d’Astrophysique de Marseille, Observatoire Astronomique de Marseille-Provence.

  3 Photon etc.

  4 Observatoire d’Astrophysique de l’Université de Ouagadougou

  5 CNRS—Observatoire Astronomique de Marseille-Provence

  ABSTRACT

  An EMCCD camera, designed from the ground up for extreme faint flux imaging, is presented.CCCP, the CCD Controller for Counting Photons, has been integrated with a CCD97 EMCCD from e2v technologies into a scientific camera at the Laboratoire d’Astrophysique Expérimentale (LAE), Université de Montréal. This new camera achieves subelectron readout noise and very low clock-induced charge (CIC) levels, which are mandatory for extreme faint flux imaging. It has been characterized in laboratory and used on the Observatoire du Mont Mégantic 1.6 m telescope. The performance of the camera is discussed and experimental data with the first scientific data are presented.

      Publications of the Astronomical Society of the Pacific

Hyperspectral Microscopy

• 2013 Evaluation of micrometer scale lateral fluctuations of transport properties in CIGS solar cells

  Evaluation of micrometer scale lateral fluctuations of transport properties in CIGS solar cells

  A. Delamarre ; D. Ory ; M. Paire ; D. Lincot ; J.-F. Guillemoles ; L. Lombez.

  CIGS is a material showing high efficiencies in photovoltaic devices although numerous questions remain about its physical mechanisms. Among them is the influence of the polycrystalline nature on global efficiencies. In order to study the spatial fluctuations of the optoelectronic parameters, two original setups are developed. Firstly a Hyperspectral Imager is used to investigate spectrally resolved luminescence images. It is also possible to calibrate it in absolute values, which means that the signal is measured in number of photons. From photoluminescence measurement we deduce maps of the quasi-Fermi level splitting with variation of 30 meV. These results are compared with a more common confocal microscope, which shows that the carrier transport has to be taken into account for the interpretation of these experiments. Using electroluminescence and reciprocity relations, we calculate map of the External Quantum Efficiency with the Hyperspectral Imager. For this investigation a second setup is developed, using Light Beam Induced Current with different excitation wavelengths. Therefore mapping of the diffusion lengths is possible, exhibiting a distribution around 1.09 μm with standard deviation of 0.10 μm. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  Read article here.

• 2012 Contactless mapping of saturation currents of solar cells by photoluminescence

  ABSTRACT

  Amaury Delamarre, Laurent Lombez, and Jean-François Guillemoles
  Institute for Research and Development on Photovoltaic Energy (IRDEP), UMR 7174, EDF R&D/CNRS/Chimie ParisTech, 6 quai Watier, 78401 Chatou, France

  We report in this letter the contactless measurement of spatially resolved photocurrent–photovoltage relationship. The method is based on hyperspectral imaging, from which we record cartography of absolute photoluminescence spectra from solar cells. Using the generalized Planck’s law, it is therefore possible to derive the quantitative value of the quasi-Fermi levels splitting, related to the voltage over the junction. It allows us to directly extract optoelectronics properties of the device with a solely optical method. As a proof of concept, we derive saturation currents of a GaAs solar cell and find a good agreement with the standard electrical measurements.

  © 2012 American Institute of Physics

   

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• 2012 Raman spectroscopy hyperspectral imager based on Bragg tunable filters

  ABSTRACT

  A new type of Raman spectroscopy hyperspectral imager based on Bragg tunable filter has been developed by University of Montreal and Photon etc. The technology of Bragg tunable filter significantly reduces the acquisition time by selecting a single wavelength in a full camera field and scanning the wavelength with a high efficiency. The transmission is continuously tunable over 400 nm range with a spectral resolution of 0.2 nm. We here present the principle of this novel Raman imaging system as well as hyperspectral images of Si taken with a spectral resolution of 0.2 nm on the whole field of view of the microscope.

  © 2012 COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

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• 2012 Conic hyperspectral dispersion mapping applied to semiconductor plasmonics

  Conic hyperspectral dispersion mapping applied to semiconductor plasmonics

  Dominic Lepage, Alvaro Jiménez, Jacques Beauvais and Jan J Dubowski

  Department of Electrical and Computer Engineering, Interdisciplinary Institute for Technological Innovation (3IT),Université de Sherbrooke, Québec, Canada.

   

• 2012 Characterization of Solar Cells Using Electroluminescence and Photoluminescence Hyperspectral Images

  ABSTRACT

  A. Delamarre; L. Lombez; J. F. Guillemoles

  We analyze photoluminescence (PL) and electroluminescence (EL) using a hyperspectral imager that records spectrally resolved luminescence images of a GaAs solar cell. Thanks to the absolute calibration, we first investigate the reciprocity relations between Solar Cell and LED and determine the External Quantum Efficiency (EQE) from EL images for a specific range of voltage. Spatial variations are observed due to series resistance effect that we can evaluate. Second, the PL experiment allows us to plot the recombination current at a given spatial location versus the quasi Fermi level splitting at the same location. Indeed, under reasonable assumptions a link can be done with the classical plot of the short circuit current versus the open circuit voltage. We therefore can optically determine optoelectronic properties such as the saturation currents. The assumptions made in this experiment are discussed in order to correctly investigate polycrystalline solar cells in the future where strong lateral variations exist.

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• 2011 A photoluminescence-based quantum semiconductor biosensor for rapid in situ detection of Escherichia coli

  Valérie Duplana, (a,b), Eric Frost (b), Jan J. Dubowskia (a)

  a Laboratory for Quantum Semiconductors and Photon-based BioNanotechnology, Department of Electrical and Computer Engineering, Faculty of Engineering, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada

  b Department of Microbiology and Infectiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec J1H 5N4, Canada

   

  This work describes a novel method of detecting Escherichia coli using photoluminescence (PL) emission from III–V quantum semiconductor (QS) devices functionalized with two different antibody-based architectures. The first approach employed self-assembled monolayers of biotinylated polyethylene glycol thiols to immobilize biotinylated antibody via neutravidin. In the second approach, we used QS microstructures coated with a thin layer of Si₃N₄ allowing direct functionalization with E. coli antibodies through hydrofluoric acid etching and glutaraldehyde-based reticulation. Atomic force, optical and fluorescence microscopy measurements were used to assess the immobilization process. Depending on the biosensing architecture, density of the immobilized bacteria was observed in the range of 0.5–0.7 bacteria/100 μm². The detection of E. coli at 10⁴ CFU/ml was achieved within less than 120 min of the bacteria exposure. It is expected that an even better sensitivity threshold could be achieved following further optimization of the method.

   

  Full article here.
• 2011 Experimental Investigation of Reciprocity Relations Between Photovoltaic Conversion and Electroluminescence of Solar Cells

   

  A. Delamarre*, L. Lombez, J.F. Guillemoles Institute of R&D on Photovoltaic Energy (UMR 7174, EDF-CNRS-ChimieParisTech)
  6 Quai Watier-BP 49, 78401 Chatou cedex, France  

  OBJECTIVES

  Photoluminescence (PL) and elecroluminescence (EL) are important characterization methods for solar cells, from which we can derive several physical properties [1]. Moreover, for multicrystalline thin films devices, spatial resolution at different scales are useful to monitor local variations. For PL measurement, absolute calibration of the emission allows to optically determine electrical properties such as open circuit voltage VOC. Our work takes profit of a Hyperspectral Imager, an experimental setup that fulfil these requirements. We obtained absolute values of the photon flux emitted by a solar cell, from which we performed a complete investigation of reciprocity relations between Solar Cell and LED [2]. This has been done on GaAs devices and achieve two purposes: validate our experimental setup on well-known solar cells, and get a better understanding of the reciprocity mechanisms.

  [1] P. Würfel, J. Phys. C, 15, 3967 (1982)
  [2] U. Rau, Pys. Rev. B, 76, 085303 (2007)
  [3] www.photonetc.com
  [4] J. Hajjar, Report 3th year Ecole Polytechnique  

  See the poster

• 2011 Luminescence Imaging of Extended Defects in SiC via Hyperspectral Imaging

   ABSTRACT

  Joshua D. Caldwell^1,a,*, Laurent Lombez^2,b, Amaury Delamarre^2,c, Jean-François Guillemoles^2,d, Brice Bourgoin^4,e, Brett A. Hull^3,f, Marc Verhaegen^4,g
  1. Naval Rasearch Laboratory, 4555 Overlook Ave, S.W. Washington, D.C. 20375, USA
  2. Chimie ParisTech, École nationale supérieure, 11, rue Pierre et Marie Curie, 75231 Parie, France
  3. Cree Inc., E. Corwallis Rd., Research Triangle Park, NC 27709
  4. Photon etc., 5795 avenue De Gaspé, #222, Montréal, Québec, H2S 2X3, Canada  

  Over the past decade, improvements in silicon carbide growth and materials has led to the development of commercialized unipolar devices such as Schottky diodes and MOSFETs, however, much work remains to realizing the goal of wide-scale commercialization of both unipolar and bipolar devices such as pin diodes or IGBTs, for high applications requiring high powers, operating in elevated temperatures or radiation environments or for many fast switching applications. Despite the great strides that have been made in reducing extended and point defect densities during this period, such defects still remain and with the push to lower off-cut angle substrates are in many cases seeing increases in prevalence. Thus, spectroscopic and imaging techniques for locating and identifying these defects are in high demand. Luminescence imaging and spectroscopy have both been utilized heavily in such work, yet simultaneously obtaining corresponding spectroscopic and spatial information from such defects is problematic. Here we report on hyperspectral imaging of electroluminescence from SiC pin diodes, whereby a stack of luminescence images are collected over a wide spectral range (400-900 nm), thereby providing the ability to both image distinct features and identify their corresponding spectral properties. This process is also equally applicable to collecting either photo- or electroluminescence from other materials or devices emitting in either the UV-Vis or NIR spectral range, as well as to reflectance, transmission or other imaging techniques.

  See poster

• 2011 Characterisation of Solar Cells Using Hyperspectral Imager

   

  A. Delamarre^1*, L. Lombez¹, J.F. Guillemoles¹, M. Verhaegen², B. Bourgoin²
  1- Institute of R&D on Photovoltaic Energy (UMR 7174, EDF-CNRS-ChimieParisTech), 6 Quai Watier-BP 49, 78401 Chatou cedex, France
  2- Photon etc, 5795 avenue de Gaspé, #222, Montréal, Québec, H2S 2X3, Canada  

  OBJECTIVES

  We develop a new characterization method based on a hyperspectral imager recording spectrally resolved images. We are able to cartography electroluminescence (EL) and photoluminescence (PL) spectra of solar cells with an absolute calibration. This will allow to study spatial variations of cell properties, like open circuit voltage and transport mechanisms [1,2]. The hyperspectral imager is compared to a classical confocal microscope.  

  CONCLUSIONS & PERSPECTIVES

  Hyperspectral imager produces spectrally resolved images of luminescence from multicristalline CIS solar cell, from which we can study its spatial inhomogeneities. On high efficiency GaAs solar cells, we got absolute measurements of EL and successfully investigated reciprocity relations. Our next step is to record quantitative maps of CIGS physical properties from PL and EL images, such as V_OC , transport parameters…  

  See poster

• 2010 High performance resonance Raman spectroscopy using volume Bragg gratings as tunable light filters

   Matthieu Paillet¹, François Meunier², Marc Verhaegen³, Sébastien Blais-Ouellette³, and Richard Martel¹

  1 Département de Chimie, Regroupement Québécois sur les Matériaux de Pointe (RQMP), Université de Montréal, Montréal, Québec H3C 3J7

  2 Département de Physique, Université de Montréal, Montréal, Québec H3C 3J7

  3 Photon etc., 5795 Avenue de Gaspé, Montréal, Québec H2S 2X3
  (Received 18 September 2009; accepted 31 March 2010; published online 20 May 2010)

  
  
  ABSTRACT

  We designed a near infrared tunable resonance Raman spectroscopy system based on a tandem of thick volume Bragg gratings (VBGs). VBGs are here the constituents of two light filtering units: a tunable laser line filter (LLF) and a tunable notch filter (NF). When adapted in a micro-Raman setup with a single stage monochromator (1800 gr/mm grating), the tandem of LLF and NF allowed measurements of Raman signals down to ±20 cm−1. The good performance and fast tunability of the VBG Raman system was demonstrated on a sulfur powder and on a bulk single-walled carbon nanotube sample through a series of 22 Stokes and anti-Stokes spectra recorded at excitation wavelengths between 800 and 990 nm. The main drawbacks of the setup are the limited spectral range to the near infrared and the small angular acceptance of the filters ( ≈ 1 mrad), which causes mainly attenuation problems with the NF. The impact of the main limitations is discussed and solutions are provided.

  
  © 2010 American Institute of Physics

   

  Review of Scientific Instruments

• 2010 Photoluminescence and Electroluminescence Mapping of CIGS Solar Cells

   

  L.Lombez*, M. Paire, A. Le Bris, J. Hajjar, A. Delamarre, L. Ribeaucourt, Z. Jehl, N. Naghavi, E. Chassaing, D. Lincot, J.F. Guillemoles  

  Institute of R&D on Photovoltaic Energy (UMR 7174, EDF-CNRS-ENSCP)
  6 Quai Watier-BP 49, 78401 Chatou cedex, France

  OBJECTIVES

  We show how the mapping of photoluminescence (PL) and electroluminescence(EL) are powerful tools to determine optoelectronic properties of thin film CIGS solar cell at the micron scale.  

  [1] P. Würfel, J. Phys. C, 15, 3967 (1982)
  [2] L. Gütay, G.H. Bauer, Thin Solid Films, 487, 8 (2005)
  [3] L. Gütay, G.H. Bauer, Thin Solid Films, 515, 6212 (2007)
  [4] M. Paire, L .Lombez, J. F. Guillemoles, D.LincotJ. Appl. Phys108, 034907 (2010)
  [5] M. Paire, L .Lombez, J. F. Guillemoles, D.Lincot Thin Solid Films, in press
  [6] J. Hajjar, Report 3th yearEcole Polytechnique  

  See the poster

• 2010 Molecular self-assembly and passivation of GaAs (001) with alkanethiol monolayers: a view towards bio-functionalization
  J.J. Dubowski^a, O. Voznyy^b and G.M. Marshalla^c
  
  a Department of Electrical and Computer Engineering, Université de Sherbrooke
  
  b Institute for Microstructural Sciences, National Research Council of Canada
  
  c Institute for Chemical Process and Environmental Technology, National Research Council of Canada
  
  ABSTRACT
  
  Properties of as prepared or nanoengineered III-V semiconductor surfaces provide attractive means for photonic detection of different adsorbants from surrounding gaseous or liquid environments. To be practical, this approach requires that the surface is made selectively sensitive (functionalized) to targeted species. In addition, such surface has also to stay stable over extended period of time to make it available for rapid testing. Numerous reports demonstrate attractive properties of GaAs for sensing applications. One of the most fundamental issues relevant to these applications concerns the ability to functionalize chemically, or biologically, the surface of GaAs. The most studied method of GaAs surface functionalization is based on formation of self-assembled monolayers (SAMs) of various n-alkanethiols, HS-(CH2)n-T (T = CH3, COOH, NH2, etc.). In spite of multi-year research concerning this issue, it has only been recently that a comprehensive picture of SAMs formation on GaAs and an understanding of the natural limitation of the SAM-GaAs interface in some bio-chemical sensing architectures has begun to emerge.

   

  Applied Surface Science
• 2009 Formation Dynamics of Hexadecanethiol Self-Assembled Monolayers on (001) GaAs Observed with Photoluminescence and Fourier Transform Infrared Spectrosc

  Chan-Kyu Kim¹, Gregory M. Marshall^1,2, Matthieu Martin¹, Michel Bisson-Viens¹, Zbigniew Wasilewski³, and Jan J. Dubowski¹
  
  1 Department of Electrical and Computer Engineering, Université de Sherbrooke 
  2 Institute for Chemical Process and Environmental Technology, National Research Council of Canada 
  3 Institute for Microstructural Sciences, National Research Council of Canada

  ABSTRACT

  The dynamics of hexadecanethiol (HDT) [HS(CH2)15CH3] chemisorption and the formation of a self-assembled monolayer (SAM) on the GaAs(001) surface was studied in situ by monitoring the photoluminescence (PL) intensity over a 20 h period. Comparing the PL time series in HDT solution with that of the bare GaAs surface similarly exposed to the ethanol solvent, we observed a two-phased evolution of the associated PL enhancement. Time-commensurate changes in the absorption frequency and intensity of the C–H stretching mode vibrations were then recorded using Fourier transform infrared spectroscopy, supporting that the PL enhancement corresponds directly with known mechanisms of ordered SAM formation. These results highlight the sensitivity with which in situ PL monitoring can reflect surface processes and underscores its potential for use in sensor applications.

  Journal of Applied Physics

• 2006 The imaging Bragg Tunable Filter: a new path to integral field spectroscopy and narrow band imaging

  Sébastien Blais-Ouellette a, Olivier Daigle a, b, Keith Taylor c

  a Photon etc

  b Université de Montréal

  c California Institute of Technology

  ABSTRACT

  An entirely new type of imaging tunable filter has been developed by Photon etc. and the California Institute of Technology. The Volume Bragg Grating based device is able to select a single wavelength for each pixel in a full camera field. The demonstration tabletop prototype was able to select images with a 2 nm bandwidth from 400 to 750 nm. Data cubes were produced through a wavelength scan from which a spectrum per pixel can be extracted. The prototype showed no image distortion, a very stable instrument profile, and high efficiency. The compact and robust tunable filter can operate from 350 nm to 2.5 mm with bandwidths from 3 Ǻ to 200 nm, showing a great potential for both ground based and space astronomy.

  Keywords: Astronomical instrumentation, Tunable filter, Volume Bragg Grating, Integral field spectroscopy, Narrowband imaging, Fabry-Perot, VBG, VPH, VHG

  spie_ibtf_2006.pdf