CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab

Grenoble, France

CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab

Grenoble, France
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Herault E.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab | Garet F.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab | Coutaz J.-L.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab
IEEE Transactions on Terahertz Science and Technology | Year: 2016

This paper investigates the limit of detection of the spectral fingerprints of a material to be identified by terahertz (THz) spectroscopy, when the material is bare or concealed by clothes. We propose a theoretical study to determine the minimum observable peak amplitude versus the refractive index and the coefficient of absorption of the sample material. We discuss the case of detecting the absorption peaks from the amplitude or phase of the transmitted or reflected spectra recorded using a THz time-domain spectroscopy system. We experimentally validate our analysis by studying a pellet sample of glutamic acid, bare or hidden under a layer of various fabrics, both in transmission and reflection configuration. This allows us to investigate the influence of various radiometric responses induced by fabrics when spectra are recorded in realistic conditions. In the reflection scheme, interference effects make the identification difficult, if not impossible. © 2015 IEEE.


Oden J.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab | Meilhan J.,CEA Grenoble | Lalanne-Dera J.,CEA Grenoble | Roux J.-F.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab | And 3 more authors.
Optics Express | Year: 2013

We present results of 2D real-time imaging of terahertz (THz) beam generated by a photoconductive antenna driven by a femtosecond oscillator. The detector, operating at room temperature, is a 320 x 240 array of antenna-coupled microbolometers with integrated CMOS read-out electronics delivering 25 images per second. High quality images of broadband THz beams covering the 0.1-2 THz range are recorded while maintaining a signal-to-noise ratio of 10 for detected THz power as low as 25 nW. The compactness of the easy-to-use uncooled camera makes it very useful for the alignment of systems such as THz time-domain spectrometers and for the characterization of emitters, optics and other components. © 2013 Optical Society of America.


Marconcini P.,University of Pisa | Cresti A.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab | Triozon F.,CEA Grenoble | Fiori G.,University of Pisa | And 5 more authors.
ACS Nano | Year: 2012

We report fully quantum simulations of realistic models of boron-doped graphene-based field-effect transistors, including atomistic details based on DFT calculations. We show that the self-consistent solution of the three-dimensional (3D) Poisson and Schrödinger equations with a representation in terms of a tight-binding Hamiltonian manages to accurately reproduce the DFT results for an isolated boron-doped graphene nanoribbon. Using a 3D Poisson/Schrödinger solver within the non-equilibrium Green's function (NEGF) formalism, self-consistent calculations of the gate-screened scattering potentials induced by the boron impurities have been performed, allowing the theoretical exploration of the tunability of transistor characteristics. The boron-doped graphene transistors are found to approach unipolar behavior as the boron concentration is increased and, by tuning the density of chemical dopants, the electron-hole transport asymmetry can be finely adjusted. Correspondingly, the onset of a mobility gap in the device is observed. Although the computed asymmetries are not sufficient to warrant proper device operation, our results represent an initial step in the direction of improved transfer characteristics and, in particular, the developed simulation strategy is a powerful new tool for modeling doped graphene nanostructures. © 2012 American Chemical Society.


Gaeremynck Y.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab | Gaborit G.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab | Duvillaret L.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab | Ruaro M.,Kapteos | Lecoche F.,Kapteos
Applied Physics Letters | Year: 2011

Based on an isotropic electro-optic crystal, a two-port pigtailed electro-optic sensor has been built. The probe allows to measure two orthogonal components of the ambient electric field. The sensor intrinsically presents a temperature-dependent free response. The two measured electric field components are orthogonal to the sensor revolution axis, leading to a transverse electro-optic probe. Magnitude and orientation of the electric field are measured simultaneously with an accuracy of 0.5 dB and 2°, respectively. The rejection of orthogonal components to the electric field vector reaches 30 dB. © 2011 American Institute of Physics.


Franc A.-L.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab | Pistono E.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab | Gloria D.,STMicroelectronics | Ferrari P.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab
IEEE Transactions on Electron Devices | Year: 2012

This paper presents optimized very high performance CMOS slow-wave shielded CPW transmission lines (S-CPW TLines). They are used to realize a 60-GHz bandpass filter, with T-junctions and open stubs. Owing to a strong slow-wave effect, the longitudinal length of the S-CPW is reduced by a factor up to 2.6 compared to a classical microstrip topology in the same technology. Moreover, the quality factor of the realized S-CPWs reaches 43 at 60 GHz, which is about two times higher than the microstrip one and corresponds to the state of the art concerning S-CPW TLines with moderate width. For a proof of concept of complex passive device realization, two millimeter-wave filters working at 60 GHz based on dual-behavior-resonator filters have been designed with these S-CPWs and measured up to 110 GHz. The measured insertion loss for the first-order (respectively, second-order) filter is $-$2.6 dB (respectively, $-$ 4.1 dB). The comparison with a classical microstrip topology and the state-of-the-art CMOS filter results highlights the very good performance of the realized filters in terms of unloaded quality factor. It also shows the potential of S-CPW TLines for the design of high-performance complex CMOS passive devices. © 2012 IEEE.


Liu C.,Japan International Center for Materials Nanoarchitectonics | Xu Y.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab | Li Y.,Nanjing University | Scheideler W.,Duke University | And 2 more authors.
Journal of Physical Chemistry C | Year: 2013

Extensive research on organic field-effect transistors (OFETs) performed to date investigated separately the electronic contact and the gate dielectric interfaces but rarely probed the relation between the two. In this report, the strong impact of the gate dielectric on the contact resistance (Rc) is revealed. With the same semiconductor dioctylbenzothienobenzothiophene (C8-BTBT) and the same device configuration, the Rc value varies greatly from 10 to 66 kΩ·cm depending on the gate dielectric interfaces. Also, the gate-voltage dependency of Rc exhibits an unexpectedly large discrepancy when different dielectrics are used. Intuitive comprehension points to the possibility that the gate dielectric interface affects the morphology of semiconductor and thus the charge injection. However, from microstructure study, albeit the semiconductor film exhibits structural defects on certain dielectrics, the impact on the injection is not crucial. Instead, bias-stress test correlates well with the contact resistance on different dielectric interfaces. At a quantitative level, gate-voltage-dependent Rc can be described by taking into account the different charge trapping induced by the gate dielectrics. The origin of the varied Rc is thus attributed to the trapped charges, which screen the gate field and reduce the carrier mobility simultaneously. A general method is proposed to examine whether the charge injection is significantly influenced by the charge trapping effect due to the gate dielectrics. © 2013 American Chemical Society.


Bernier M.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab | Garet F.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab | Coutaz J.-L.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab
IEEE Transactions on Terahertz Science and Technology | Year: 2013

In this paper, we propose a method to determine the refractive index and the absorption coefficient of samples showing spectral bands of very low transmission. The method, takes advantages of both transmission and reflection terahertz time-domain spectroscopy (THz-TDS) to obtain more precise optical constants than when only reflection measurement is used. It has been then validated using pellets made of maltose, which exhibits resonant lines within the THz spectral range. © 2011-2012 IEEE.


Charlet B.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab | Bastard L.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab | Broquin J.E.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab
Optics Letters | Year: 2011

Embedded optical sensors always require more compact, stable, and powerful laser sources. In this Letter, we present a fully integrated passively Q-switched laser, which has been realized by a Ag+=Na3+ ion exchange on a Nd+-doped phosphate glass. A BDN-doped cellulose acetate thick film is deposited on the waveguide, acting as an upper cladding and providing a distributed saturable absorption. At λ = 1054nm, the device emits pulses of 1:3 ns FWHM with a repetition rate of 28 kHz. These performances, coupled with the 1kW peak power, are promising for applications such as supercontinuum generation. © 2011 Optical Society of America.


Herault E.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab | Hofman M.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab | Garet F.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab | Coutaz J.-L.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab
Optics Letters | Year: 2013

The structure of most of fabrics is an almost periodic network of interlaced yarns or threads, whose periodicity is of the order of the terahertz wavelength. We report here on the diffraction of terahertz electromagnetic waves by the yarn network in common cloths. In the case of linen, this effect could lead to overestimating (by a factor as large as 3) the absorption when determined from the classical terahertz time-domain experiment. Our results are confirmed by a HFSS numerical simulation. © 2013 Optical Society of America.


Nazarov M.,Moscow State University | Coutaz J.-L.,CNRS Institute for Microelectronics, Electromagnetism, and Photonics: Hyperfrequency and Characterization lab
Journal of Infrared, Millimeter, and Terahertz Waves | Year: 2011

Due to their long propagation length at a metal surface in the far infrared, surface plasmons make potentially feasible the design and realization of 2D integrated terahertz systems over ametallic substrate. In this article, we present a review of recentworks dedicated to surface plasmon properties on structured metallic surfaces.We study excitation,propagation, diffraction and reflection of terahertz surface plasmon on shallow gratings and of spoof plasmons on deep sub-wavelength structures. The analysis of the experimentaldata supplied by terahertz timedomain spectroscopy allows us to point out the main parameters that govern this diffraction process and the propagation of a surface plasmon over aflat or corrugated metal surface. © Springer Science+Business Media, LLC 2011.

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