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(122) Production(s) de VACHER R.
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Mécanismes d’atténuation du son dans les verres
Auteur(s): Ruffle B. , Foret M., Vacher R.
(Séminaires)
SAGEM (Paris, FR), 2009-07-16 |
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Boson peaks and elastic properties in glasses
Auteur(s): Ruffle B., Ayrinhac Simon, Courtens E., Vacher R., Foret M., Wischnewski Andreas, Buchenau Uli
Conference: Workshop on Topology, Structure, and Dynamics in Non-Crystalline Solid (Paris, FR, 2009-09-20)
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Optical noise of a 1550 nm fiber laser as an underwater acoustic sensor 
Auteur(s): Orsal Bernard, Hey Tow Keny, Vacher R., Dureisseix David
Conference: 20th International Conference on Noise and Fluctuations - ICNF 2009 (Pisa, IT, 2009-06-14)
Actes de conférence: Noise and Fluctuations, vol. 1129 p.379-386 (2009)
Ref HAL: hal-00413722_v1
DOI: 10.1063/1.3140478
Exporter : BibTex | endNote
Résumé: The goal of this presentation is to provide first results concerning the optical noise of a fiber laser used as an underwater acoustic sensor: hydrophone. The main sensor characteristics are: (1) A sensitivity allowing to detect all noise levels above background sea noise (the so-called deep-sea state 0). Among other applications, one may mention: seismic risk prevention, oil prospection, ship detection, etc. (2) An optical noise reduced to its minimal value: it is the lower bound below which no acoustic pressure variation is detectable.We therefore present here the first results for the expected sensitivity of the acousto-optic sensors, the frequency and amplitude of optical noises induced by the fiber laser and all the devices on the optical line. These results exemplify the possible detection of signal levels as low as the deep-sea state noise 0, especially for low frequency bandwidths, from several Hertz up to several kiloHertz.
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Optical noise of a 1550 nm fiber laser as an underwater acoustic sensor
Auteur(s): Orsal Bernard, Vacher R., Dureisseix David
(Autres publications)
, 2008
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Optical noise of a 1550 nm fiber laser as an underwater acoustic sensor
Auteur(s): Orsal Bernard, Faye N., Hey Tow Keny, Vacher R., Dureisseix David
Conference: 5th International Conference on Unsolved Problems on Noise and Fluctuations in Physics, Biology \& High Technology - UPoN 2008 (Lyon, FR, 2008-06)
Actes de conférence: Proceedings of the 5th International Conference on Unsolved Problems on Noise and Fluctuations in Physics, Biology & High Technology, vol. p.1-4 (2008)
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The vibrational excitations of glasses in the boson-peak region: application to borates
Auteur(s): Vacher R., Ruffle B., Hehlen B., Guimbretiere Guillaume, Simon Guilhem, Courtens E.
(Article) Publié:
European Journal Of Glass Science And Technology: Part B - Physics And Chemistry Of Glasses, vol. 49 p.19-25 (2008)
Ref HAL: hal-00512610_v1
Exporter : BibTex | endNote
Résumé: There exists a special interest in investigating acoustical and optical vibrations of glasses in the one THz frequency region. The main experimental tools that are used to this effect are briefly discussed. The current understanding of the boson-peak vibrations and of their resonance with acoustic branches are explained. Specific new results on the origin of the boson peak and on the end of acoustic branches are presented for borates.
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Nature of the hyper-Raman active vibrations of lithium borate glasses
Auteur(s): Simon Guilhem, Hehlen B., Vacher R., Courtens E.
(Article) Publié:
Journal Of Physics: Condensed Matter, vol. 20 p.155103 (2008)
Ref HAL: hal-00526787_v1
DOI: 10.1088/0953-8984/20/15/155103
WoS: 000254329200005
Exporter : BibTex | endNote
14 Citations
Résumé: Hyper-Raman spectra of two lithium borate glasses, 4B(2)O(3): Li2O and 2B(2)O(3): Li2O, are compared to those of pure boron oxide glass, upsilon-B2O3. A mode analysis is performed using a structural model based on the symmetry of the elementary structural units (ESUs) constituting the glasses. Most spectral components arise from internal vibrations of BO3 triangles, B3O3 boroxol rings, and BO4 tetrahedra. In particular, a mode associated with stretching motions of BO4 units can be assigned to a vibration of F-2 symmetry in the T-d tetrahedral point group. The hyper-Raman scattering intensity of its transverse optic component appears to be proportional to the number of BO4 units in the glass. The boson peak observed in hyper-Raman scattering arises from external modes of rigid ESUs which correspond to librational motions coupled to their translations. The scattering strength of these modes strongly decreases with increasing Li concentration. In pure upsilon-B2O3, external modes of boroxols presumably dominate this scattering. The decrease in the boroxol concentration in lithium borate glasses correlates with the apparent hardening of the boson peak.
Commentaires: 0953-8984
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