Nouvelle méthode de mesure de largeur de raie d'un laser utilisant la rétrodiffusion de Rayleigh dans une fibre optique

Session orale 7 « Instrumentations et capteurs » [Me2.4]National audienceNous proposons une méthode de mesure de largeur de raie d'un laser basée sur une caractérisation du bruit interférométrique causé par la rétrodiffusion de Rayleigh dans une fibre optique du signal avec lui même. Les résultats expérimentaux sont comparés à ceux obtenus par une mesure classique d'auto-hétérodynage. En comparaison à des méthodes classiques, notre technique de mesure est simple à mettre en œuvre et permet d'analyser, pour une grande gamme de longueurs d'onde, des largeurs de raies allant d'une plusieurs dizaines de kHz à plusieurs centaines de MHz sans avoir à modifier le montage expérimental

First demonstration of a 12 DFB fiber laser array on a 100 GHz ITU grid, for underwater acoustic sensing application

International audienceWe report for the first time a multiplexed array of 12 distributed feedback fiber lasers (DFB FLs) on a single optical fiber, separated by only 100 GHz (0.8 nm) in the C-band. These lasers are pumped by a 200 mW laser diode at 1480 nm with no apparent impact on the sensor noise floor despite the fact that the residual reflections from adjacent gratings may be enhanced due to the smaller wavelength separation. Each DFB FL, especially developed for serial multiplexing, exhibits low lasing threshold typically between 1 and 2 mW, low intensity noise and very low frequency noise (less than 30 dB re 1 Hz²/Hz at 1 kHz from optical carrier). From these experimental results, extension to 32 DFB FLs array (on 100 GHz ITU grid) multiplexed on one fiber will be discussed

Effets d'une faible contre-réaction optique sur des lasers à fibre DFB pour applications capteurs

National audienceNous étudions l'effet d'une faible réflection externe sur des lasers à fibre à contre-réaction répartie (DFB FLs). Nous démontrons expérimentalement que la phase optique accumulée sur un aller-retour dans la cavité étendue et la réflectivité associée au miroir externe modifient la puissance de sortie et la fréquence d'émission d'un DFB FL. Comme pour un laser à semiconducteurs (SC) contre-réactionné, à réflectivité externe donnée, l'amplitude des variations est constante pour ces deux paramètres quelle que soit la longueur de la cavité externe

6 mW and 30 mW laser threshold for respectively 1st and 2nd Brillouin Stokes order in a Ge10As24Se68 chalcogenide fiber

International audienceA compact second-order Stokes Brillouin fiber laser made of microstructured chalcogenide glass is reported for the first time. This laser has very low optical pump-power threshold for Stokes conversion: 6 mW for first order and only 30 mW for second order with nonresonant pumping

Lasers Brillouin à fibre microstructurée en verre de chalcogénure à très faibles seuils

National audienceL'utilisation de fibres microstructurées en verre de chalcogénure ouvre la voie à la réalisation des lasers à fibre Brillouin présentant des seuils très bas comparativement aux lasers en fibre silice, de l'ordre du milliWatt en pompage non-résonant. Ces lasers sont compacts et par nature mono-fréquence. Leurs caractéristiques de bruit sont améliorées par rapport à la pompe comme cela a été déjà prédit pour les lasers Brillouin

Brillouin fiber laser using As38Se62 suspended-core chalcogenide fiber

International audienceIn this paper, an all-fiber Brillouin laser ring cavity using a 3-m-long suspended-core chalcogenide As38Se62 fiber is reported for the first time to our knowledge. For a nonresonant ring cavity with no servo-locking, a laser threshold power of 37 mW and an efficiency of 26 % were obtained for a fiber having a core diameter of 5 μm. The linewidth of the Brillouin fiber laser and the pump laser were respectively measured to be below 4 kHz, the resolution of our autocorrelator, and 250 kHz, thus showing the linewidth-narrowing nature of the Brillouin laser. This result paves the way to compact Brillouin lasers with low threshold power and good spectral purity. A full experimental Brillouin characterization is also reported. We measured a Brillouin gain spectrum of 14.2 MHz, a Brillouin gain coefficient of 5.6x10-9 m/W and a Brillouin frequency shift of 7.95 GHz in our fiber

Relative intensity noise and frequency noise of a compact Brillouin laser made of As38Se62 suspended-core chalcogenide fiber

International audienceRelative intensity noise and frequency noise have been measured for the first time for a single-frequency Brillouin chalcogenide As38Se62 fiber laser. This is also the first demonstration of a compact suspended-core fiber Brillouin laser, which exhibits a low threshold power of 22 mW and a slope efficiency of 26% for nonresonant pumping

Phase sensitivity to axial strain of microstrustured optical silica fibers

International audienceWe compare, thanks to a Sagnac interferometer, the phase sensitivity to strain of different microstructured optical silica fibers (MSF) that we design and fabricate. Our results show that when a same elongation is applied to different MSF, the induced phase change is equal or lower than the one obtained for a standard fiber, showing no advantage on this parameter for sensing applications

Towards More Coherent Sources Using a Microstructured Chalcogenide Brillouin Fiber Laser

International audienceUp to 16 dB frequency noise reduction and a linewidth 8 times narrower that of the pump source is reported for the Stokes component in a compact Brillouin fiber laser made of chalcogenide microstructured fiber. Since the pump wave is not resonant in the ring cavity, an active stabilization of the laser is not primordial thus making the system simpler and cheaper. Although only a 3 metre-long microstructured chalcogenide fiber was used as gain medium, a very low laser threshold power of 6 mW was obtained for nonresonant pumping. The linewidth-narrowing effect achieved in our BFL cavity is also discussed

Linewidth-narrowing and intensity noise reduction of the 2nd order Stokes component of a low threshold Brillouin laser made of Ge10As24Se68 chalcogenide fiber

International audienceA compact second-order Stokes Brillouin fiber laser made of microstructured chalcogenide fiber is reported for the first time. This laser required very low pump power for Stokes conversion: 6 mW for first order lasing and only 30 mW for second order lasing with nonresonant pumping. We also show linewidth-narrowing as well as intensity noise reduction for both the 1st and 2nd order Stokes component when compared to that of the pump source