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Search Results: 1 - 10 of 25 matches for " Khelifa Djerroud "
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Lasers for coherent optical satellite links with large dynamics
Nicola Chiodo,Khelifa Djerroud,Ouali Acef,Andre Clairon,Peter Wolf
Physics , 2013, DOI: 10.1364/AO.52.007342
Abstract: We present the experimental realization of a laser system for ground to satellite optical Doppler ranging at the atmospheric turbulence limit. Such a system needs to display good frequency stability (a few parts in 10^{-14}) whilst allowing large and well controlled frequency sweeps of +/- 12 GHz at rates exceeding 100 MHz/s. Furthermore it needs to be sufficiently compact and robust for transportation to different astronomical observation sites where it is to be interfaced with satellite ranging telescopes. We demonstrate that our system fulfills those requirements and should therefore allow operation of ground to low Earth orbit satellite coherent optical links limited only by atmospheric turbulence.
A coherent optical link through the turbulent atmosphere
Khelifa Djerroud,Ouali Acef,Andre Clairon,Pierre Lemonde,Catherine N. Man,Etienne Samain,Peter Wolf
Physics , 2009, DOI: 10.1364/OL.35.001479
Abstract: We describe the realization of a 5 km free space coherent optical link through the turbulent atmosphere between a telescope and a ground target. We present the phase noise of the link, limited mainly by atmospheric turbulence and mechanical vibrations of the telescope and the target. We discuss the implications of our results for applications, with particular emphasis on optical Doppler ranging to satellites and long distance frequency transfer.
First direct determination of the Boltzmann constant by an optical method
Christophe Daussy,Mickael Guinet,Anne Amy-Klein,Khelifa Djerroud,Yves Hermier,Stephan Briaudeau,Christian J. Bordé,Christian Chardonnet
Physics , 2007, DOI: 10.1103/PhysRevLett.98.250801
Abstract: We have recorded the Doppler profile of a well-isolated rovibrational line in the \nu2 band of 14NH3. Ammonia gas was placed in an absorption cell thermalized by a water-ice bath. By extrapolating to zero pressure, we have deduced the Doppler width which gives a first measurement of the Boltzmann constant, kB, by laser spectroscopy. A relative uncertainty of 2x10-4 has been obtained. The present determination should be significantly improved in the near future and contribute to a new definition of the kelvin.
HCOOH high resolution spectroscopy in the 9.18$μ$m region
Franck Bielsa,Khelifa Djerroud,Andrei Goncharov,Albane Douillet,Tristan Valenzuela,Christophe Daussy,Laurent Hilico,Anne Amy-Klein
Physics , 2007, DOI: 10.1016/j.jms.2007.10.003
Abstract: We report on higly accurate absolute frequency measurement against a femtosecond frequency comb of 6 saturated absorption lines of formic acid (HCOOH) with an accuracy of 1 kHz. We also report the frequency measurement of 17 other lines with an accuracy of 2 kHz. Those lines are in quasi coincidence with the 9R(36) to 9R(42) CO$_2$ laser emission lines and are probed either by a CO$_2$ or a widely tunable quantum cascade laser phase locked to a master CO$_2$ laser. The relative stability of two HCOOH stabilized lasers is characterized by a relative Allan deviation of 4.5 10$^{-12}$ $\tau^{-1/2}$. They give suitable frequency references for H$_2^+$ Doppler free two-photon spectroscopy.
Determination of the Boltzmann constant by laser spectroscopy as a basis for future measurements of the thermodynamic temperature
Cyril Lemarchand,Khelifa Djerroud,Beno?t Darquié,Olivier Lopez,Anne Amy-Klein,Christian Chardonnet,Christian J. Bordé,Stephan Briaudeau,Christophe Daussy
Physics , 2009, DOI: 10.1007/s10765-010-0755-3
Abstract: In this paper, we present the latest results on the measurement of the Boltzmann constant kB, by laser spectroscopy of ammonia at 10 ?m. The Doppler absorption profile of a ro-vibrational line of an NH3 gas sample at thermal and pressure equilibrium is measured as accurately as possible. The absorption cell is placed inside a large 1m3 thermostat filled with an ice-water mixture, which sets the temperature very close to 273.15 K. Analysing this profile, which is related to the Maxwell-Boltzmann molecular speed distribution, leads to a determination of the Boltzmann constant via a measurement of the Doppler width (proportional tosqrt(kBT)). A spectroscopic determination of the Boltzmann constant with an uncertainty as low as 37 ppm is obtained. Recent improvements with a new passive thermostat lead to a temperature accuracy, stability and homogeneity of the absorption cell better than 1 ppm over a day.
Measurement of the Boltzmann constant by the Doppler broadening technique at a 3,8x10-5 accuracy level
Khelifa Djerroud,Cyril Lemarchand,Alexandre Gauguet,Christophe Daussy,Stephan Briaudeau,Beno?t Darquié,Olivier Lopez,Anne Amy-Klein,Christian Chardonnet,Christian J. Bordé
Physics , 2009, DOI: 10.1016/j.crhy.2009.10.020
Abstract: In this paper, we describe an experiment performed at the Laboratoire de Physique des Lasers and dedicated to an optical measurement of the Boltzmann constant. With the proposed innovative technique, determining comes down to an ordinary frequency measurement. The method consists in measuring as accurately as possible the Doppler absorption profile of a rovibrational line of ammonia in thermal equilibrium. This profile is related to the Maxwell-Boltzmann molecular velocity distribution along the laser beam. A fit of the absorption line shape leads to a determination of the Doppler width proportional to sqrt(kT) and thus to a determination of the Boltzmann constant. The laser source is an ultra-stable CO2 laser with a wavelength . The absorption cell is placed in a thermostat keeping the temperature at 273.15 K within 1.4 mK. We were able to measure with a relative uncertainty as small as 3.8x10-5, which represents an improvement of an order of magnitude for an integration time comparable to our previous measurement published in 2007 [1]
Small-Force Measurement by Photo-Elastic Transducer  [PDF]
Naceur-Eddine Khelifa
Optics and Photonics Journal (OPJ) , 2014, DOI: 10.4236/opj.2014.41003
Abstract:

The use of stress-induced changes in a crystal of a monolithic solid-state laser by external force as a way for micro-force detection and measurement is described. In fact, the application of an unknown force on the resonator-amplifier crystal of a solid-state laser leads to a measurable change in the frequency of the beat note associated with the orthogonal polarisation components of the oscillating laser mode. Here we report our first measurements of the sensitivity of a photo-elastic force sensor, realised with a monolithic (4 × 4) mm plano-convex cylindrical crystal, and compare them with the results obtained by other authors for different configurations and dimensions of the laser sensor. The reported results are in a good mutual agreement but show notable discrepancies with theoretical predictions, especially for high sensitivities obtained when the dimensions of the laser sensor are small.

Al Wahda Mall
Malika Khelifa
Humanising Language Teaching , 2009,
Abstract:
A completeness result for the simply typed $λμ$-calculus
Karim Nour,Khelifa Saber
Mathematics , 2009,
Abstract: In this paper, we define a realizability semantics for the simply typed $\lambda\mu$-calculus. We show that if a term is typable, then it inhabits the interpretation of its type. This result serves to give characterizations of the computational behavior of some closed typed terms. We also prove a completeness result of our realizability semantics using a particular term model.
A semantics of realisability for the classical propositional natural deduction
Karim Nour,Khelifa Saber
Mathematics , 2009,
Abstract: In this paper, we introduce a semantics of realisability for the classical propositional natural deduction and we prove a correctness theorem. This allows to characterize the operational behaviour of some typed terms.
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