Marc Brunel
University of Rennes
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Publication
Featured researches published by Marc Brunel.
IEEE Photonics Technology Letters | 2001
Mehdi Alouini; B. Benazet; Marc Vallet; Marc Brunel; P. Di Bin; Fabien Bretenaker; A. Le Floch; Philippe Thony
An optical source of microwaves with very low phase noise for communications and radar systems is realized and tested. It is obtained by dual-frequency operation of a diode pumped Er,Yb:glass laser. An electrooptic crystal inserted inside the resonator permits both to tune the frequency difference between orthogonally polarized eigenstates, and to turn the laser into a voltage controlled oscillator. An optical phase-locked loop is then implemented in the GHz range, resulting in a measured instrument limited 3 dB-linewidth of 10 Hz. The phase noise is shown to be -100 dBc/Hz at 10-kHz offset.
Optics Letters | 2005
Marc Brunel; Axelle Amon; Marc Vallet
Two-frequency operation of a composite Er,Yb:glass-LiTaO3 monolithic microlaser is demonstrated at 1.53 microm. The thermo-optic effect of the intracavity birefringent crystal makes it possible to control the wavelengths of the two orthogonal linearly polarized eigenstates. It provides a tunable beat note from 0 to 60 GHz. Direct evaluation of the Lamb-type coupling constant C between the two eigenstates is obtained from a single intensity noise spectrum measurement, yielding values from 0.33 to 0.86, depending on transverse and axial distributions of the eigenstates. Applications to radar and telecommunication systems are discussed.
Applied Optics | 2008
Nicolas Verrier; Sébastien Coëtmellec; Marc Brunel; Denis Lebrun
We apply digital in-line holography to image opaque objects through a thick plano-concave pipe. Opaque fibers and opaque particles are considered. Analytical expression of the intensity distribution in the CCD sensor plane is derived using a generalized Fresnel transform. The proposed model has the ability to deal with various pipe shapes and thicknesses and compensates for the lack of versatility of classical digital in-line holography models. Holograms obtained with a 12 mm thick plano-concave pipe are then reconstructed using a fractional Fourier transform. This method allows us to get rid of astigmatism. Numerical and experimental results are presented.
Optics Express | 2010
Nicolas Verrier; Clément Remacha; Marc Brunel; Denis Lebrun; Sébastien Coëtmellec
Digital in-line holography is used to visualize particle motion within a cylindrical micropipe. Analytical expression of the intensity distribution recorded in the CCD sensor plane is derived using the generalized Huygens-Fresnel integral associated with the ABCD matrices formalism. Holograms obtained in a 100microm in diameter micropipe are then reconstructed using fractional Fourier transformation. Astigmatism brought by the cylindrical micropipe is finally used to select a three dimensional region of interest in the microflow and thus to improve axial localization of objects located within a micropipe. Experimental results are presented and a short movie showing particle motion within a micropipe is given.
Optics Express | 2011
Antoine Rolland; Goulc'Hen Loas; Marc Brunel; Ludovic Frein; Marc Vallet; Mehdi Alouini
We propose an optoelectronic phase-locked loop concept which enables to stabilize optical beat notes at high frequencies in the mm-wave domain. It relies on the use of a nonlinear-response Mach-Zehnder modulator. This concept is demonstrated at 100 GHz using a two-axis dual-frequency laser turned into a voltage controlled oscillator by means of an intracavity electrooptic crystal. A relative frequency stability better than 10⁻¹¹ is reported. This approach of optoelectronic down conversion opens the way to the realization of continuously tunable ultra-narrow linewidth THz radiation.
international topical meeting on microwave photonics | 2010
Antoine Rolland; Ludovic Frein; Marc Vallet; Marc Brunel; F. Bondu; Thomas Merlet
An optically-carried microwave synthesis working at 40 GHz is demonstrated by using a two-frequency microchip laser inside a digital phase-locked loop. We report a relative frequency stability better than 2.5!10!11. Different frequency sweeping formats are programmed.
Applied Physics Letters | 1997
G. Ropars; P. Langot; Marc Brunel; Marc Vallet; F. Bretenaker; A. Le Floch; K.D. Choquette
The polarizations and frequencies of the two eigenstates of a vertical cavity surface emitting laser with an external cavity containing a quarter-wave plate are theoretically and experimentally analyzed. It is shown that the polarizations of these eigenstates are fixed by the neutral axes of the quarter-wave plate. The optical pulses at a frequency equal to a half of the free spectral range of the external cavity, observed through a linear polarizer, are due to beats between the two eigenstates. All these features show that such polarization self-modulated lasers oscillate in a single round trip.
IEEE Transactions on Terahertz Science and Technology | 2014
Antoine Rolland; Guillaume Ducournau; Gwennaël Danion; Goulc'Hen Loas; Marc Brunel; Alexandre Beck; Fabio Pavanello; E. Peytavit; Tashin Akalin; M. Zaknoune; J.F. Lampin; F. Bondu; Marc Vallet; Pascal Szriftgiser; D. Bacquet; Mehdi Alouini
A beatnote, tunable from dc to 1 THz, provided by a dual-frequency laser is used to feed an unitravelling carrier photodiode in order to produce a highly coherent THz signal radiated by a transverse-electromagnetic-horn antenna. The THz signal is detected and analyzed by a subharmonic mixer coupled to an electrical spectrum analyzer. All components involved in this experiment operate at room temperature without phase locking the beatnote. So far, the dynamic range evolves from 58 dB at 282 GHz to 15 dB at 1.026 THz, and the measured linewidth is better than 30 kHz. Linewidth narrowing using a Brillouin fiber laser pumped by the dual-frequency laser leads to a beatnote of 500-Hz linewidth at 1 THz.
International Journal of Optics | 2014
Marc Brunel; Huanhuan Shen; Sébastien Coëtmellec; Gérard Gréhan; Tony Delobel
We present a mathematical formalism to predict speckle-like interferometric out-of-focus patterns created by irregular scattering objects. We describe the objects by an ensemble of Dirac emitters. We show that it is not necessary to describe rigorously the scattering properties of an elliptical irregular object to predict some physical properties of the interferometric out-of-focus pattern. The fit of the central peak of the 2D autocorrelation of the pattern allows the prediction of the size of the scattering element. The method can be applied to particles in a size range from a tenth of micrometers to the millimeter.
Optics Letters | 2008
Marc Brunel; Marc Vallet
We demonstrate experimentally the pulse-to-pulse coherence of the beat note produced by a dual-polarization passively Q-switched Nd:YAG laser subjected to a frequency-shifted, polarization-rotated, optical feedback. The reinjection of one laser eigenstate into the other eigenstate ensures the phase-locking of the beat note against an external acoustic reference wave at the onset of each pulse, circumventing the intrinsic memory loss of the optical phase between successive pulses. It opens the possibility to generate optically a coherent pulsed beat note in the radio-frequency range with a subhertz linewidth, i.e., over thousands of pulses. An application to lidar radar is discussed.