Publications by authors named "Antoine Godard"

21 Publications

  • Page 1 of 1

Long-wave infrared multi-wavelength optical source for standoff detection of chemical warfare agents.

Appl Opt 2020 Dec;59(35):11156-11166

We have designed and built a wavelength-tunable optical source for standoff detection of gaseous chemicals by differential absorption spectrometry in the long-wave infrared. It is based on a nanosecond 2 µm single-frequency optical parametric oscillator, whose idler wave is amplified in large aperture Rb:PPKTP crystals. The signal and idler waves are mixed in crystals to produce single-frequency tunable radiation in the 7.5-10.5 µm range. The source was integrated into a direct detection lidar to measure sarin and sulfur mustard inside a closed chamber, in an integrated path configuration with a noncooperative target.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/AO.410053DOI Listing
December 2020

Actively Q-switched tunable single-longitudinal-mode 2 µm Tm:YAP laser using a transversally chirped volume Bragg grating.

Opt Express 2020 Feb;28(4):5013-5021

A pulsed, single longitudinal mode, wavelength-tunable Tm:YAP laser is reported. We demonstrate 1 kHz stable operation with 230 µJ, 50 ns pulses and a spectrum linewidth narrowed below 4 pm (FWHM) close to the Fourier transform limit by use of a volume Bragg grating and a YAG etalon. The output wavelength was tuned from 1940 to 1960 nm owing to a transverse chirp of the period of the Bragg grating.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OE.384499DOI Listing
February 2020

Wavelength tunable, single-longitudinal-mode optical parametric oscillator with a transversally chirped volume Bragg grating.

Opt Lett 2020 Feb;45(3):607-610

We report on single-longitudinal-mode (SLM) operation of a low-threshold optical parametric oscillator, with a 17 nm tunability near 2 µm. The oscillator uses a MgO:PPLN crystal in Type 0 quasi-phase-matching configuration, pumped by a 1.064 µm SLM laser. Despite the huge acceptance bandwidth near-degeneracy of MgO:PPLN, spectral selection down to a SLM is achieved by combining a volume Bragg reflector and Vernier filtering in nested signal and idler cavities. Tunability over 17 nm is demonstrated owing to a transverse chirp of the grating period of the Bragg reflector.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OL.379581DOI Listing
February 2020

Quartz Enhanced Photoacoustic Spectroscopy Based on a Custom Quartz Tuning Fork.

Sensors (Basel) 2019 Mar 19;19(6). Epub 2019 Mar 19.

DPHY, ONERA, Université Paris Saclay, F-91123 Palaiseau, France.

We have designed and fabricated a custom quartz tuning fork (QTF) with a reduced fundamental frequency; a larger gap between the prongs; and the best quality factor in air at atmospheric conditions ever reported, to our knowledge. Acoustic microresonators have been added to the QTF in order to enhance the sensor sensitivity. We demonstrate a normalized noise equivalent absorption () of 3.7 × 10 W.cm.Hz for CO₂ detection at atmospheric pressure. The influence of the inner diameter and length of the microresonators has been studied, as well as the penetration depth between the QTF's prongs. We investigated the acoustic isolation of our system and measured the Allan deviation of the sensor.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/s19061362DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6471020PMC
March 2019

Spectrotemporal dynamics of a picosecond OPO based on chirped quasi-phase-matching: erratum.

Opt Lett 2018 02;43(3):494

This erratum is to correct an error made in our paper [Opt. Lett.40, 280 (2015)OPLEDP0146-959210.1364/OL.40.000280] regarding the sign of the quasi-phase matching chirp rate.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OL.43.000494DOI Listing
February 2018

Atmospheric boundary layer CO remote sensing with a direct detection LIDAR instrument based on a widely tunable optical parametric source.

Opt Lett 2017 Oct;42(20):4044-4047

We report on the capability of a direct detection differential absorption lidar (DIAL) for range resolved and integrated path (IPDIAL) remote sensing of CO in the atmospheric boundary layer (ABL). The laser source is an amplified nested cavity optical parametric oscillator (NesCOPO) emitting approximately 8 mJ at the two measurement wavelengths selected near 2050 nm. Direct detection atmospheric measurements are taken from the ground using a 30 Hz frequency switching between emitted wavelengths. Results show that comparable precision measurements are achieved in DIAL and IPDIAL modes (not better than a few ppm) on high SNR targets such as near range ABL aerosol and clouds, respectively. Instrumental limitations are analyzed and degradation due to cloud scattering variability is discussed to explain observed DIAL and IPDIAL limitations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OL.42.004044DOI Listing
October 2017

Wide and fast dispersion tuning of a picosecond OPO based on aperiodic quasi-phase matching using an axially chirped volume Bragg grating.

Opt Lett 2016 Sep;41(17):4060-3

We report on a widely tunable synchronously pumped picosecond optical parametric oscillator (OPO) combining an aperiodically poled MgO-doped LiNbO3 crystal as a broadband gain medium and an axially chirped volume Bragg grating as a spectral filtering dispersive element. Translation of the Bragg grating along the beam axis enables wavelength tuning over 215 nm around 3.82 μm and provides spectral narrowing. Rapid continuous tuning over 150 nm in 100 ms is demonstrated.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OL.41.004060DOI Listing
September 2016

Rapidly tunable optical parametric oscillator based on aperiodic quasi-phase matching.

Opt Express 2016 May;24(10):11112-25

A new optical parametric oscillator (OPO) architecture with high tuning speed capability is demonstrated. This device exploits the versatility offered by aperiodic quasi-phase matching (QPM) to provide a broad parametric gain spectrum without changing the temperature, angle, or position of the nonlinear crystal. Rapid tuning is then straightforwardly achieved using a fast intracavity spectral filter. This concept is demonstrated here for a picosecond synchronously pumped OPO containing an aperiodically poled MgO-doped LiNbO3 crystal and a rapidly tunable spectral filter based on a diffraction grating. Tuning over 160 nm around 3.86 μm is achieved at fixed temperature and a fast tuning over 30 nm in 40 μs is demonstrated. Different configurations are tested and compared. The cavity length detuning is analyzed and discussed. This device is successfully used to detect N2O by absorption. This approach could be generalized to other spectral ranges (e.g., visible) and temporal regimes (e.g., continuous-wave or nanosecond).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OE.24.011112DOI Listing
May 2016

Dual-wavelength source from 5%MgO:PPLN cylinders for the characterization of nonlinear infrared crystals.

Opt Express 2013 Nov;21(23):28886-91

We conceived a unique fully parametric source based on two independent cylindrical OPOs simultaneously pumped by the same Nd:YAG laser. Each OPO delivers more than 2 mJ and is continuously tunable between 1.41 µm and 4.3 µm. This source is of particular interest for the study of the generation of infrared parametric light in nonlinear crystals. It was validated by performing difference frequency generation experiments in CdSe crystals with output in the range 8 - 10 µm.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OE.21.028886DOI Listing
November 2013

Tunable optical parametric amplification of a single-frequency quantum cascade laser around 8 μm in ZnGeP2.

Opt Lett 2013 Oct;38(20):4046-9

We demonstrate optical parametric amplification in ZnGeP(2) (ZGP) of the radiation emitted by a single-frequency continuous-wave quantum cascade laser (QCL) in the range 7.8-8.4 μm. The ZGP amplifier is pumped by a single-frequency parametric source at 2210 nm. For a pump energy of 6 mJ, we report an average gain of 50 over this range and a maximum gain of 111 for 7.5 mJ. An exponential trend is observed when changing the pump energy, with very good agreement with theory. These features are of valuable interest for increasing the standoff detection range of hazardous chemicals and explosives by QCL-based backscattering spectroscopy systems.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OL.38.004046DOI Listing
October 2013

Microsecond fiber laser pumped, single-frequency optical parametric oscillator for trace gas detection.

Opt Lett 2013 Jul;38(13):2165-7

ONERA, the French Aerospace Lab, Chemin de la Hunière, 91761 Palaiseau, France.

We report on the first microsecond doubly resonant optical parametric oscillator (OPO). It is based on a nested cavity OPO architecture allowing single longitudinal mode operation and low oscillation threshold (few microjoule). The combination with a master oscillator-power amplifier fiber pump laser provides a versatile optical source widely tunable in the 3.3-3.5 μm range with an adjustable pulse repetition rate (from 40 to 100 kHz), high duty cycle (~10(-2)) and mean power (up to 25 mW in the idler beam). The potential for trace gas sensing applications is demonstrated through photoacoustic detection of atmospheric methane.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OL.38.002165DOI Listing
July 2013

Application of self-regulation theory and motivational interview for improving oral hygiene: a randomized controlled trial.

J Clin Periodontol 2011 Dec 6;38(12):1099-105. Epub 2011 Sep 6.

Université de Rennes 1, Faculté d'Odontologie, Université Européenne de Bretagne, Rennes, Cedex, France.

Aim: Because patient adherence to oral hygiene is essential for periodontal treatment success, the aim of the study was to assess whether a motivational interview addressing the five dimensions of Leventhal's theory performed better than conventional basic instruction on improving compliance with plaque control among patients with periodontitis.

Materials And Methods: A randomized controlled clinical trial design was used in which a group of patients underwent a motivational interview in addition to classical consultation. A control group received only the standard consultation. The O'Leary Plaque Index was used to judge the oral hygiene at baseline and at 1 month follow-up. Patient satisfaction with the dental visit was scored using a specific questionnaire.

Results: At baseline, the mean full mouth plaque score varied between 55% (experimental group) and 58% (control group). Patients in the experimental group had a higher oral hygiene improvement (21 ± 20% versus 4 ± 5%, p < 0.001) 1 month post-treatment. The motivational interview resulted in greater satisfaction scores compared with those of patients in the control group: 10.55 ± 1.53 versus 8.82 ± 2.40, p = 0.014.

Conclusions: This new concept of motivational interview is a promising approach and can be useful for counselling-related periodontal disorders.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/j.1600-051X.2011.01782.xDOI Listing
December 2011

Picosecond tunable mode locking of a Cr2+:ZnSe laser with a nonlinear mirror.

Opt Lett 2011 Mar;36(5):751-3

ONERA-The French Aerospace Laboratory, Palaiseau, France.

We report on a nonlinear mirror (NLM) scheme that enables, for the first time to the best of our best knowledge, tunable mode locking of a Cr2+:ZnSe laser in the picosecond regime. The NLM-used as the output coupler of the laser cavity-consists of a periodically poled lithium niobate (PPLN) crystal with a fan-out grating coupled with a dichroic mirror and a wedged dispersive YAG plate. The Cr2+:ZnSe laser, pumped by a CW thulium-doped fiber laser, delivers 85 ps pulses at a repetition rate of 220 MHz with a 300 mW average power. Thanks to the use of a fan-out PPLN crystal, we benefit from the wide tunability of the Cr2+:ZnSe laser and achieve mode locking over the whole 2.44-2.55 μm range while maintaining a narrow-linewidth emission suitable for time-resolved nonlinear spectroscopy applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OL.36.000751DOI Listing
March 2011

Management of thermal effects in high-repetition-rate pulsed optical parametric oscillators.

Opt Lett 2010 Nov;35(21):3667-9

ONERA-the French Aerospace Lab, Chemin de la Hunière, F-91761 Palaiseau Cedex, France.

We report on the investigation of thermal effects in high-repetition-rate pulsed optical parametric oscillators emitting in the mid-IR. We find that the thermal load induced by the nonresonant idler absorption plays a critical role in the emergence of thermally induced bistability. We then demonstrate a significant improvement of the conversion efficiency (more than 30%) when a proper axial temperature gradient is applied to the nonlinear crystal by use of a two-zone temperature-controlled oven.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OL.35.003667DOI Listing
November 2010

Second order coherence of broadband down-converted light on ultrashort time scale determined by two photon absorption in semiconductor.

Opt Express 2010 Sep;18(19):20401-8

DMPH, Onera-the French Aerospace Laboratory, Palaiseau, France.

We study the photon correlation properties of broadband parametric down-converted light. The measurement of the photon correlation is carried out thanks to a modified Hanbury Brown-Twiss interferometer based on two photon absorption in GaAs detector. Since this method is not affected by the phase matching conditions of the detecting apparatus (so called "final state post-selection"), the detection bandwidth can be extremely large. This is illustrated by studying, with the same apparatus, the degree of second order coherence of parametric light in both degenerate and non-degenerate cases. We show that our experiment is able to determine the coherent as well as the incoherent contributions to the degree of second order coherence of parametric light with a time resolution in the fs range scale.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OE.18.020401DOI Listing
September 2010

Picosecond synchronously pumped ZnGeP2 optical parametric oscillator.

Opt Lett 2010 Jul;35(13):2197-9

ONERA the French Aerospace Lab, Chemin de la Hunière 91761 Palaiseau, France.

We report on the experimental operation of a picosecond, singly resonant, synchronously pumped optical parametric oscillator (SPOPO) based on a ZnGeP(2) (ZGP) crystal. The ZGP SPOPO is pumped with the idler radiation from a diffraction-grating-tuned periodically poled lithium niobate SPOPO emitting a continuous picosecond pulse train (Delta tau approximately 8 ps, f=76 MHz). The noncritically 90 degree phase-matched ZGP SPOPO is tuned in the 3.8-5.6 microm range by tuning the pump wavelength (2.25-2.5 microm). As high as approximately 800 mW of average power is emitted at 4 microm.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OL.35.002197DOI Listing
July 2010

High-energy single-longitudinal mode nearly diffraction-limited optical parametric source with 3 MHz frequency stability for CO2 DIAL.

Opt Lett 2009 Jul;34(13):2069-71

ONERA, The French Aerospace Lab, Chemin de la Hunière, Palaiseau, France.

We report on a 2.05 microm nanosecond master oscillator power amplifier optical parametric source for CO2 differential-absorption lidar. The master oscillator consists of an entangled-cavity nanosecond optical parametric oscillator based on a type II periodically poled lithium niobate crystal that provides highly stable single-longitudinal-mode radiation. The signal emission is amplified by a multistage parametric amplifier to generate up to 11 mJ in a nearly diffraction-limited beam with an M2 quality factor of approximately 1.5 while maintaining single-longitudinal-mode emission with a frequency stability better than 3 MHz rms. This approach can be readily applied to the detection of various greenhouse gases.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/ol.34.002069DOI Listing
July 2009

Fresnel phase matching: exploring the frontiers between ray and guided wave quadratic nonlinear optics.

Opt Express 2008 Oct;16(22):18457-78

Office National d'Etudes et de Recherches Aérospatiales, Chemin de la Hunière, Palaiseau, France.

Fresnel phase matching is a convenient and universal way to phase match nonlinear three-wave mixing by total internal reflection in isotropic materials like common semiconductors. This technique makes use of the large relative phase lag between the interacting waves at total internal reflection, and was suggested by the nonlinear optics pioneers in the 70's; it has been worked out by several teams since then but, quite unexpectedly, has never succeeded in producing enough parametric gain to achieve optical parametric oscillation. We show that this failure stems mostly from a basic law of nonlinear reflection, which leads to a spatial walk-off between the pump and the generated parametric waves, resulting in unexpected destructive interference patterns between the waves while bouncing back and forth between the interfaces. Ray tracing or plane wave analysis gives an incomplete representation of the phenomenon while highly multimodal nonlinear guided wave theory reconciles the different views. Very good agreement between the presented theory and experiments is demonstrated in gallium arsenide samples.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/oe.16.018457DOI Listing
October 2008

Passively mode-locked slow pump optical parametric oscillators.

Opt Lett 2008 Jan;33(2):153-5

Johns Hopkins University, Baltimore Maryland 21218, USA.

We predict that employing a Bragg grating to simultaneously phase match and induce large temporal walk-off between the signal and slow propagating pump in a nonlinear crystal can be conducive to development of passively mode locked optical parametric oscillators in which cw near-infrared pump is efficiently converted into short middle-infrared pulses.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/ol.33.000153DOI Listing
January 2008

Generation of mid-infrared radiation by self-difference frequency mixing in chromium-doped zinc selenide.

Opt Lett 2006 Jan;31(2):220-2

Office National d'Etudes et de Recherches Aérospatiales, Chemin de la Hunière, Palaiseau, France.

We report what we believe to be the first demonstration of mid-infrared generation (approximately 9 microm) by self-difference frequency generation in Fresnel birefringence quasi-phase-matched Cr:ZnSe laser slabs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/ol.31.000220DOI Listing
January 2006

Relaxation of the single-mode emission conditions in extended-cavity semiconductor lasers with a self-organizing photorefractive filter.

Appl Opt 2004 Jun;43(17):3543-7

Laboratoire Charles Fabry de l'Institut d'Optique, Centre National de la Recherche Scientifique, Université Paris-Sud, Centre Scientifique d'Orsay, Bâtiment 503, F-91403 Orsay, France.

Commercial 1.55-microm extended-cavity semiconductor lasers provide single-mode operation that can be continuously tuned over a range larger than 100 nm without mode hopping. But such performance requires delicate factory adjustment and high mechanical stability of the external cavity. Furthermore, at high emission power the tuning range is limited to small values because of the annoying multimode operations that sometimes occur. We have shown that the alignment constraints can be relaxed by use of an intracavity photorefractive filter. Here we present new results obtained with a crystal with low absorption and high photorefractive gain. We demonstrate that, without inducing excessive additional loss, we can preserve single-mode emission at an output power higher than the maximum power obtained in the absence of a photorefractive crystal over the full tuning range of the laser.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/ao.43.003543DOI Listing
June 2004
-->