Academic literature on the topic 'OPO Fibre'
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Journal articles on the topic "OPO Fibre":
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Antipov, O. L., D. B. Kolker, A. A. Dobrynin, Yu A. Getmanovskii, V. V. Sharkov, M. A. Chuvakova, A. R. Akhmatkhanov, V. Ya Shur, I. A. Shestakova, and S. V. Larin. "Mid-IR optical parametric oscillation and second harmonic generation of repetitively pulsed output of a fibre-laser pumped Tm3+ :YAP laser in a fan-out periodically poled MgO:LiNbO3 crystal." Quantum Electronics 52, no. 3 (March 1, 2022): 254–61. http://dx.doi.org/10.1070/qel18006.
Abstract:
Abstract The nonlinear optical frequency conversions of repetitively pulsed output of a 1941-nm Tm3+ : YAP laser pumped by a cw 1670-nm fibre laser are studied experimentally. Both mid-IR optical parametric oscillation (OPO) and second harmonic generation (SHG) are obtained in the same periodically poled MgO : LiNbO3 crystal with a fan-out domain design by tuning the grating period and temperature. The energy conversion efficiency of the degenerate OPO at 3820 – 3970 nm exceeds 43 % at a 0.5 kHz repetition rate, while the energy conversion efficiency of SHG at 970.5 nm reaches 34 %.
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Ashimatey, Bright S., Brett J. King, Stephen A. Burns, and William H. Swanson. "Evaluating glaucomatous abnormality in peripapillary optical coherence tomography enface visualisation of the retinal nerve fibre layer reflectance." Ophthalmic and Physiological Optics 38, no. 4 (March 30, 2018): 376–88. http://dx.doi.org/10.1111/opo.12449.
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Südmeyer, T., J. Aus der Au, R. Paschotta, U. Keller, P. G. R. Smith, G. W. Ross, and D. C. Hanna. "Novel ultrafast parametric systems: high repetition rate single-pass OPG and fibre-feedback OPO." Journal of Physics D: Applied Physics 34, no. 16 (August 7, 2001): 2433–39. http://dx.doi.org/10.1088/0022-3727/34/16/307.
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Ashimatey, Bright S., Brett J. King, and William H. Swanson. "Functional characteristics of glaucoma related arcuate defects seen on OCT en face visualisation of the retinal nerve fibre layer." Ophthalmic and Physiological Optics 41, no. 2 (January 25, 2021): 437–46. http://dx.doi.org/10.1111/opo.12780.
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Cheloni, Riccardo, and Jonathan Denniss. "Depth‐resolved variations in visibility of retinal nerve fibre bundles across the retina in enface OCT images of healthy eyes." Ophthalmic and Physiological Optics 41, no. 1 (November 4, 2020): 179–91. http://dx.doi.org/10.1111/opo.12756.
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Grzegorczyk, Adrian, and Marcin Mamajek. "A 70 W thulium-doped all-fiber laser operating at 1940 nm." Photonics Letters of Poland 11, no. 3 (September 30, 2019): 81. http://dx.doi.org/10.4302/plp.v11i3.928.
Abstract:
An all-fiber thulium-doped fiber laser operating at a wavelength of 1940 nm is reported. A maximum output continuous-wave power of 70.7 W with a slope efficiency of 59%, determined with respect to the absorbed pump power, was demonstrated. The laser delivered almost a single-mode beam with a beam quality factor of < 1.3.Full Text: PDF ReferencesM. N. Zervas and C. A. Codemard, "High Power Fiber Lasers: A Review", IEEE J. Sel. Top. Quantum Electron. 20, 0904123 (2014). CrossRef D. J. Richardson, J. Nilsson, and W. A. Clarkson. "High power fiber lasers: current status and future perspectives [Invited]", J. Opt. Soc. Am. B 27, B63 (2010). CrossRef J. Swiderski, A. Zajac, and M. Skorczakowski, "Pulsed ytterbium-doped large mode area double-clad fiber amplifier in MOFPA configuration", Opto-Electron. Rev. 15, 98 (2007). CrossRef M. Eckerle et al. "High-average-power actively-modelocked Tm3+ fiber lasers", Proc. SPIE 8237, 823740 (2012). CrossRef J. Swiderski, D. Dorosz, M. Skorczakowski, and W. Pichola, "Ytterbium-doped fiber amplifier with tunable repetition rate and pulse duration", Laser Phys. 20, 1738 (2010). CrossRef P. Grzes and J. Swiderski, "Gain-Switched 2-μm Fiber Laser System Providing Kilowatt Peak-Power Mode-Locked Resembling Pulses and Its Application to Supercontinuum Generation in Fluoride Fibers", IEEE Phot. J. 10, 1 (2018). CrossRef S. Liang et al. "Transmission of wireless signals using space division multiplexing in few mode fibers", Opt. Express 26, 6490 (2018). CrossRef J. Swiderski, M. Michalska, and P. Grzes, "Broadband and top-flat mid-infrared supercontinuum generation with 3.52 W time-averaged power in a ZBLAN fiber directly pumped by a 2-µm mode-locked fiber laser and amplifier", Appl. Phys. B 124, 152 (2018). CrossRef F. Zhao et al. "Electromagnetically induced polarization grating", Sci. Rep. 8, 16369 (2018). CrossRef J. Sotor et al. "Ultrafast thulium-doped fiber laser mode locked with black phosphorus", Opt. Lett. 40, 3885 (2015). CrossRef M. Olivier et al. "Femtosecond fiber Mamyshev oscillator at 1550 nm", Opt. Lett. 44, 851 (2019). CrossRef J. Swiderski and M. Michalska, "Over three-octave spanning supercontinuum generated in a fluoride fiber pumped by Er & Er:Yb-doped and Tm-doped fiber amplifiers", Opt. Laser Technol. 52, 75 (2013). CrossRef C.Yao et al. "High-power mid-infrared supercontinuum laser source using fluorotellurite fiber", Optica 5, 1264 (2018). CrossRef J. Swiderski and M. Maciejewska, "Watt-level, all-fiber supercontinuum source based on telecom-grade fiber components", Appl. Phys. B 109, 177 (2012). CrossRef O. Traxer and E. X. Keller, "Thulium fiber laser: the new player for kidney stone treatment? A comparison with Holmium:YAG laser", World J. Urol., 1-12 (2019). CrossRef M. Michalska, et al. "Highly stable, efficient Tm-doped fiber laser—a potential scalpel for low invasive surgery", Laser Phys. Lett. 13, 115101 (2016). CrossRef R. L. Blackmon et al. "Thulium fiber laser ablation of kidney stones using a 50-μm-core silica optical fiber", Opt. Eng., 54, 011004 (2015). CrossRef A. Zajac et al. "Fibre lasers – conditioning constructional and technological", Bull. Pol. Ac.: Tech. 58, 491 (2010). CrossRef C. Guo, D. Shen, J. Long, and F. Wang, "High-power and widely tunable Tm-doped fiber laser at 2 \mu m", Chin. Opt. Lett. 10, 091406 (2012). CrossRef F. Liu et al. "Tandem-pumped, tunable thulium-doped fiber laser in 2.1 μm wavelength region", Opt. Express 27, 8283 (2019). CrossRef H. Ahmad, M. Z. Samion, K. Thambiratnam, and M. Yasin, "Widely Tunable Dual-Wavelength Thulium-doped fiber laser Operating in 1.8-2.0 mm Region", Optik 179, 76 (2019). CrossRef N. M. Fried, "Thulium fiber laser lithotripsy: An in vitro analysis of stone fragmentation using a modulated 110‐watt Thulium fiber laser at 1.94 µm", Lasers Surg. Med. 37, 53 (2005). CrossRef N. M. Fried, "High‐power laser vaporization of the canine prostate using a 110 W Thulium fiber laser at 1.91 μm", Lasers Surg. Med. 36, 52 (2005). CrossRef E. Lippert et al. "Polymers Designed for Laser Applications-Fundamentals and Applications", Proc. SPIE 6397, P639704 (2006). CrossRef N. Dalloz et al. "High power Q-switched Tm3+, Ho3+-codoped 2μm fiber laser and application for direct OPO pumping", Proc. SPIE 10897, 108970J (2019). CrossRef N. J. Ramírez-Martinez, M. Nunez-Velazquez, A. A. Umnikov, and J. K. Sahu, "Highly efficient thulium-doped high-power laser fibers fabricated by MCVD", Opt. Express 27, 196 (2019). CrossRef T. Ehrenreich et al. "1-kW, All-Glass Tm:fiber Laser", Proc. SPIE 7580, 758016 (2010). DirectLink L. Shah et al. "Integrated Tm:fiber MOPA with polarized output and narrow linewidth with 100 W average power", Opt. Express 20, 20558 (2012). CrossRef H. Zhen-Yue, Y. Ping, X. Qi-Rong, L. Qiang, and G. Ma-Li, "227-W output all-fiberized Tm-doped fiber laser at 1908 nm", Chin. Phys. B 23, 104206 (2014). CrossRef
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Gspann, Thurid S., Nicola Montinaro, and Alan H. Windle. "CNT fibres - yarns between the extremes." MRS Proceedings 1752 (2015): 117–23. http://dx.doi.org/10.1557/opl.2015.251.
Abstract:
AbstractThe carbon nanotube community swims in the sea of superlatives. Researchers expect mechanical performance to achieve two extremes, an ultrastrong fibre taking us into space, and a superlubricant saving energy otherwise lost as heat. We examine CNT fibres in the light of traditional yarn science and present an interpretation of properties which combines aspects of these two extremes of performance.
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Teixeira, Flavia, Bruna Aparecida dos Santos, Graziela Nunes, Jaqueline Machado Soares, Luane Aparecida do Amaral, Gabriel Henrique Oliveira de Souza, Juliano Tadeu Vilela de Resende, et al. "Addition of Orange Peel in Orange Jam: Evaluation of Sensory, Physicochemical, and Nutritional Characteristics." Molecules 25, no. 7 (April 4, 2020): 1670. http://dx.doi.org/10.3390/molecules25071670.
Abstract:
Orange is highly nutritious and a source of phytochemical compounds. However, its by-products are usually discarded. In this study, we evaluated the effect of orange peel (OP) addition in orange jam on sensory, physicochemical, and nutritional characteristics. Four jam formulations were elaborated with different OP levels: OP0 (standard), OP4, OP8, and OP12 (Orange Peel 0, 4, 8 and 12%, respectively). All samples were evaluated for sensory acceptability, and physicochemical and nutritional composition. The addition of 12% orange peel in jam reduced (p < 0.05) the acceptability for all evaluated attributes, as well as overall acceptance and purchase intention. However, OP utilization increased (p < 0.05) the levels of water activity, soluble solids, titratable acidity, and sugars. Soluble solids/titratable acidity ratio, luminosity (L*), and yellow content (b*) decreased in all added OP jams, while red content (a*) increased. No change in the pH and moisture values of the product were observed after OP addition. Ash, protein, lipid, dietary fiber, ascorbic acid, carotenoids, phenolic compounds, and antioxidant capacity values increased after OP addition, while carbohydrate and energy content decreased. A texture test showed that adhesiveness decreased, while gumminess, chewiness, and elasticity increased after OP addition. We concluded that the addition of up to 8% orange peel in jam maintains sensory acceptability similar to that of the standard product. OP addition is a viable alternative to improve some of the product’s physicochemical and nutritional characteristics.
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Borshchev, V. Ya, and Yu A. Apporotova. "Organization of Solid Waste Management at an Industrial Company." Voprosy sovremennoj nauki i praktiki. Universitet imeni V.I. Vernadskogo, no. 3(81) (2021): 007–13. http://dx.doi.org/10.17277/voprosy.2021.03.pp.007-013.
Abstract:
The main types of waste in the production of bulk insulation made of polyester fiber are considered. The physicochemical, toxic and fire hazardous properties of materials have been investigated. The paper presents the findings of the study of an industrial waste management enterprise (OOO Kotovsky Zavod Netkanykh Materialov), where the work on waste management is quite clearly and highly efficient.
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Çayıroğlu, H., G. Filik, İ. Coşkun, A. Gül Filik, H. Çayan, and A. Şahin. "Spraying opened sugar beet pulp silage with oregano essential oil helps to sustain quality and stability." South African Journal of Animal Science 50, no. 1 (April 16, 2020): 9–16. http://dx.doi.org/10.4314/sajas.v50i1.2.
Abstract:
This study was conducted to determine the effects of spraying oregano essential oil (OEO) onto sugar beet pulp silage (SBPS) on silage quality and aerobic stability after opening. A factorial experiment with three replicates of three treatments and four time periods was conducted using laboratory-type plastic silos. The treatments were an untreated control, silage sprayed with 10 ml/75 cm2 OEO, and silage sprayed with 20 ml/75 cm2 OEO. The silages were sampled at 0, 72, 120, and 168 hours after spraying. Temperature, L*, a*, and b* colour values, pH, water-soluble carbohydrates, crude nutrient contents, Fleig score, metabolizable energy (ME) value, lactic acid bacteria (LAB), total live bacteria (TLB), yeast, and mould formation were assessed. Spraying OEO onto SBPS did not affect L*, a*, and b* values, pH, water-soluble carbohydrates, and Fleig score values, but decreased temperature. Spraying OEO onto the silage increased organic matter, ether extract, acid detergent fibre, neutral detergent fibre and acid detergent lignin contents without affecting crude protein, crude fibre, nitrogen free extract, and ME contents. Irrespective of treatment, crude protein, ether extract, acid detergent fibre, acid detergent lignin, nitrogen free extract, Fleig score, and ME contents of silages increased with time after spraying. The OEO spraying reduced LAB, TLB, and yeast contents in silages. In conclusion, OEO spraying onto opened SBPS reduced LAB, TLB, and yeast formation and stopped mould growth up to 72 hours without affecting their nutritional properties, suggesting that OEO could be used to ensure the stability of SBPS.
Keywords: aerobic stability, mould growth, silage microbiology, nutrients, feeding management
Dissertations / Theses on the topic "OPO Fibre":
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Ghawas, Muhammad. "Sources picosecondes et femtosecondes à base de fibre dopées Ytterbium et applications." Electronic Thesis or Diss., Bordeaux, 2023. http://www.theses.fr/2023BORD0463.
Abstract:
Les recherches industrielles ou académiques autour laser délivrant des impulsions ultracourtes reposent de plus en plus sur la technologie des lasers à fibre. Elles s’appuient sur les avantages intrinsèques des systèmes à fibre, tels que leur stabilité, compacité, l'excellente qualité modale du faisceau délivré, leur robustesse et leur facilité d'utilisation. Au cours de ce travail, nous avons réalisé l’étude détaillée d’un laser à fibre délivrant des impulsions picosecondes fonctionnant dans un régime de dispersion normale (ANDi). Ce laser a par la suite été déployé pour étudier de la génération paramétrique dans une fibre à cristal photonique. Nous avons tout d’abord développé une source laser à fibre de haute puissance délivrant des impulsions picosecondes dont on peut accorder à la fois la longueur d'onde centrale et la largeur spectrale. La source développée autour d’une cavité en anneau comprend la combinaison d’une fibre d'ytterbium à grande surface modale du type « rod-type », une fente et un réseau de diffraction en transmission. À la longueur d'onde centrale de ∼ 1030 nm et à un taux de répétition de 78 MHz, ce laser délivre des impulsions picosecondes avec une puissance moyenne allant jusqu'à 25 W. La durée des impulsions peut être ajustée en continu entre ∼ 1,8 ps et ∼ 4,5 ps alors que l'énergie des impulsions varie entre ∼ 320 nJ et ∼ 225 nJ. Nous avons également démontré que la longueur d'onde centrale des impulsions laser peut-être finement réglée entre ∼ 1010 nm à ∼ 1060 nm tout en s’assurant que l'énergie de l'impulsion est supérieure ∼ 150 nJ. Nous avons également développé un modèle numérique pour rendre compte de l'ensemble de nos données expérimentales. Nos simulations sont en bon accord avec nos résultats expérimentaux. Les impulsions délivrées par cette source ont été utilisées pour étudier et réaliser un oscillateur paramétrique optique dans une fibre optique. Les ondes signal et idler générées résultent d’un mélange paramétrique à quatre-onde induit dans une fibre à cristal photonique. Cet OPO à fibre est simplement résonnant pour l’onde signal. L'efficacité de conversion pour l’onde signal est proche de 20 %. Le profil de dispersion spectrale de la fibre à cristal photonique et l’accordabilité spectrale de notre laser de pompe nous ont permis de générer des ondes du signal (resp. idler) comprises respectivement entre ∼ 770 nm et ∼ 1000 nm ( ∼ 1130 nm et ∼ 1590nm) lorsque la longueur d'onde des impulsions pompe est ajustée entre ∼ 1024 nm et ∼ 1059 nmUltrashort laser pulses in both industrial and research applications progressively rely on fiber laser technology, guided by its intrinsic benefits, for instance, stability, compact nature, excellent beam quality, robustness, and easy operation. In this work, a detailed study has been done to investigate picosecond fiber laser working in an all-normal-dispersion (ANDi) regime for the application of parametric generation in photonic crystal fiber. In summary, we have developed a high-power fiber laser source delivering picosecond pulses with tunability both in central wavelength and spectral width. It incorporates a combination of a large-mode-area rod-type ytterbium fiber, a slit, and a transmission grating inside the ring laser cavity configuration. At the central wavelength of ∼ 1030 nm and with a repetition of 78 MHz, this laser delivers picosecond pulses with an average power of up to 25 W. The pulse duration can be continuously adjusted from ∼ 1.8 ps to ∼ 4.5 ps and pulse energy from ∼ 320 nJ and ∼ 225 nJ, respectively. Additionally, we have also demonstrated that the central wavelength of the laser pulse can be finely tuned from ∼ 1010 nm to ∼ 1060 nm while keeping the pulse energy above ∼ 150 nJ. We have also proposed a numerical model to account for the ensemble of our experimental data and the simulations are in good agreement with the experimental data. The output of this fiber oscillator is propagated through the photonic crystal fiber for the parametric generation of the signal (higher frequencies than the pump) and idler (lower frequencies than the pump). The fiber OPO singly-resonant cavity was built in such a way that only signal wavelengths are allowed to propagate through it. The conversion efficiency for the signal was close to 20 % in the fiber OPO. Based on the dispersion profile of the photonic crystal fiber and our homebuilt tunable pump laser, the signal wavelength (resp. idler) was tuned from ∼ 770 nm to ∼ 1000 nm (∼ 1130 nm to ∼ 1590nm) for the corresponding pump wavelengths of ∼ 1024 nm to ∼ 1059 nm
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Brieussel, Alexandre. "Mini squeezers towards integrated systems." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066104/document.
Abstract:
Les états comprimés de lumière sont des états quantiques qui peuvent être utilisés dans de nombreux protocoles pour le calcul quantique et la communication quantique. Leur génération en laboratoire a déja été étudiée au paravant, mais ils manquent en general encore de compacité et de praticitalité pour une intégration facile dans des expériences plus grandes. Cette thèse considère deux expériences: celle menée en France, le miniOPO; et celle menée en Australie, le SquOPO. Les deux sont de nouvelles conceptions de sources compactes d' état de lumière comprimé dans l'optique d'une integration future. Le miniOPO est une cavité linéaire d'une longueur de 5 mm entre l'extrémité d'une fibre et un miroir incurvé avec un cristal de PPKTP de 1 mm à l'intérieur. Le vide comprimé généré dans cette cavité est couplé dans la fibre pour pouvoir être envoyé vers un systeme de mesure, (dispositif homodyne) ou vers une plus grande expérience. La cavité est résonnante pour la frequence de lumiere comprimé et pour celle de la pompe. Le systeme est verrouillé en fréquence en utilisant des effets auto-verrouillant du à l'absorption de la pompe dans le cristal. La double résonance est obtenue en changeant la température du cristal. Deux fibres différentes ont été testées dans cette expérience, une fibre mono-mode standard, et une fibre photonique mono-mode avec un diametre de mode plus important. Le vide comprimé obtenu est encore assez faible (0.5dB avec la fibre standard et 0.9dB pour la fibre photonique), mais un certain nombre d'améliorations sont étudiées pour augmenter ces niveaux dans l'avenir. Le SqOPO est une cavité carrée monolithique dans un cristal de niobate de lithium. En utilisant quatre réflexions total internes sur les quatre faces du crystal, il est possible de definir un mode optique de cavité pour la frequence du vide comprimé et celle du mode de la pompe. La lumière est couplée dans le résonateur en utilisant une frustration de la réflexion interne par des prismes. La distance entre les prismes et le résonateur défini la force du couplage de la lumière, ce qui nous permet de contrôler la la finesse de la lumière dans le résonateur. En utilisant des prismes biréfringents, il est possible de controler indépendamment la finesse des deux fréquences dans le résonateur pour atteindre un régime optimum. Comme pour le MiniOPO, La fréquence de resonance de la cavité est verouillé grace à l' absorption de la lumière de pompage dans le résonateur, ce qui permet d' atteindre l'auto-verrouillage. La double résonance est contrôlée par le réglage de la température du cristal. et la position des prismes. Nous avons démontré 2.6dB de vide comprimé avec ce système. Encore une fois, la quantité de compression est faible, mais des améliorations qui pourraient être mises en œuvre dans l'avenir sont discutéesSqueezed states of light are quantum states that can be used in numerous protocols for quantum computation and quantum communication. Their generation in labora- tories has been investigated before, but they still lack compactness and practicality to easily integrate them into larger experiments. This thesis considers two experiments: one conducted in France, the miniOPO; and one conducted in Australia, the SquOPO. Both are new designs of compact sources of squeezed states of light towards an integrated system. The miniOPO is a linear cavity of 5mm length between the end of a fiber and a curved mirror with a PPKTP crystal of 1mm inside it. The squeezing generated in this cavity is coupled into the fiber to be able to be brought to a measurement device (homodyne) or to a larger experiment. The cavity is resonant for the squeezed light and the pump light, and locked in frequency using self-locking effects due to absorption of the pump in the crystal. The double resonance is achieved by changing the temperature of the crystal. Two different fibers have been tested in this experiment, a standard single-mode fiber and a photonic large core single-mode fiber. The squeezing obtained is still quite low (0.5dB with the standard fiber and 0.9dB for the photonic fiber) but a number of ameliorations are investigated to increase these levels in the future. The SqOPO is a monolithic square cavity made in a Lithium Niobate crystal using four total internal reflections on the four faces of the square to define an optical mode for the squeezed mode and the pump mode. The light is coupled in the resonator using frustrated internal reflection with prisms. The distance between the prisms and the resonator defined the coupling of the light, which allows us to control the finesse of the light in the resonator and by using birefringent prisms it is possible to tune independently the two frequencies in the resonator to achieve an optimal regime. The frequency of the light is locked using absorption of the pump light in the resonator to achieve self-locking, and double resonance is controlled by tuning the temperature of the crystal. We demonstrated 2.6dB of vacuum squeezing with this system. Once again, the amount of squeezing is low, but ameliorations that could be implemented in the future are discussed
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Le, Méhauté Simon. "Étude et réalisation d'un lidar dial cohérent fibré à 1.65 µm pour la mesure simultanée de la vitesse du vent et de la concentration de méthane." Thesis, Littoral, 2020. http://www.theses.fr/2020DUNK0555.
Abstract:
Les fuites de méthane soulèvent à la fois des problématiques environnementales et sécuritaires, particulièrement dans l'industrie pétrolière. Le contrôle de panaches en temps réel permettrait de prévenir d'éventuels drames humains et catastrophes écologiques. Dans ce contexte, un volet du projet NAOMI, impliquant TOTAL E&P et l'ONERA, vise à développer des instruments de télédétection capables de localiser (résolution spatiale de l'ordre de 100 m) et de caractériser les fuites majeures de méthane à une distance de sécurité (1 km) sur le terrain. Pour répondre à ce cahier des charges, ce travail de thèse décrit l'étude, la conception et la caractérisation d'un prototype lidar fibré, émettant dans le domaine proche infrarouge (1.65 µm) : VEGA (VEnt et GAz). L'utilisation d'un schéma de détection hétérodyne permet en effet d'envisager un système bi-fonction, capable de mesurer simultanément la vitesse du vent via le décalage Doppler (utile pour évaluer la dispersion d'un panache) et la concentration de méthane par la technique DIAL. Au laboratoire, des mesures intégrées (cible à 2.2 km) ont démontrée, pour la première fois à notre connaissance avec un lidar hétérodyne, la sensibilité de l'instrument au méthane. L'exactitude de ces estimations du niveau atmosphérique (1.95 ± 0.26 ppm en 1 s d'accumulation) s'avère satisfaisante pour l'application visée (impliquant une concentration très supérieure). La participation à une campagne de mesure en 2018 (à Lacq) a démontré le bon comportement du prototype lidar sur le terrain, justifiant le choix d'une architecture tout-fibré. L'utilisation de plusieurs stratégies de mesures (simples, multi lignes de visée, multi spectrale) a également souligné la capacité de VEGA à identifier et quantifier la concentration au sein de lâchers de méthane contrôlés, à environ 200 (résolution de 30 m) dans une gamme étendue de débit de 0.1 à 300 g.s-¹. Au cours de la campagne, les erreurs aléatoires observées, de l'ordre ± 10 - 100 ppm en 1 sec d'accumulation s'avèrent conformes aux modèles théoriques. Des extrapolations de la précision à des distances supérieures montrent toutefois la nécessité d'améliorer le prototype (au travers de pistes réalistes, identifiées dans ce document) pour atteindre une portée kilométrique. Finalement, les bases pour l'estimation autonome du flux, combinant les mesures gaz et vent , ont été poséesEspecially in the oil and gas industry, methane leaks threaten both safety and environment. The real-time monitoring of such plumes could prevent potential human or ecological disasters. In this context, one part of NAOMI project, involving TOTAL and ONERA, aims to develop remote sensing tools capable of locating (with a spatial resolution of 100 m) and characterize major methane leaks from a safety distance (1 km) on the field. To meet these specifications, the present work describes the study, design and performances assessments of a fiber lidar emitting in the near infrared (1.65 µm) : VEGA ("VEnt et GAz", French for "wind and gaz"). The choice of a coherent detection scheme allows to consider a dual-function system, able to simultaneously measure wind speed with Doppler shift (useful to assess plume dynamic) and methane concentration with the DIAL technique. In the lab, integrated-path measurements (target at 2.2 km) have shown, a first to our knowledge with a coherent lidar, VEGA's sensibility to methane. The accuracy of ambient level measurements (1.95 ± 0.26 ppm for 1 s averaging) is seen to be satisfying for the target application (involving much higher concentration). During a field campaign in 2018 (Lacq, France), the lidar has shown a good thermo-mechanical behaviour, justifying the choice of an all-fibered architecture. The use of several measurement procedures (simple, several laser lines of sight, several wavelengths) allowed VAGA to identify controlled methane leaks at 200 m (30 m resolution) in a wide range of flow rates (from 0.1 to 300 g.s-¹. During the campaign, the observed statistical errors, in the ±10 to 100ppm range for 1 s averaging, are in good agreement with theoretical models. Assessing these errors at greater distances shows, nonetheless, a need to improve the lidar (through mentioned improvement tracks) to reach an adequate precision at 1 km. Eventually, the basis for autonomous flow rate estimation, combining both wind and gas data, had been presented
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Rosolem, João Batista. "Amplificadores ópticos de dupla passagem incorporando fibras compensadoras de dispersão." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/18/18133/tde-31102005-125254/.
Abstract:
Amplificadores a fibra dopada com érbio de dupla passagem (DP-EDFA) contendo fibras compensadoras de dispersão (DCF) são estudados nesta tese. Os DP-EDFAs são uma alternativa para amplificadores de baixo custo e bom desempenho, sobretudo para utilização em redes metropolitanas. Devido a sua estrutura de dupla passagem, outras funções podem ser facilmente inseridas em seu circuito óptico, incrementando sua funcionalidade e reduzindo o custo envolvido. Considerando ainda que a compensação da dispersão é crítica para sistemas WDM de alta velocidade, um interessante tópico de investigação, que será bastante explorado nesta tese, refere-se a embutir uma fibra compensadora de dispersão dentro no circuito do DP-EDFA. Estudos experimentais são conduzidos, mostrando as vantagens e os problemas associados a algumas topologias de circuitos de DP-EDFAs. Um circuito original de DP-EDFA contendo DCF é proposto e caracterizado em termos de ganho e figura de ruído para diversas aplicações multicanal e multibanda dentro do espectro de transmissão da fibra óptica. Caracterizações sistêmicas em termos de taxa de erro de bit são também conduzidasDouble pass erbium doped fiber amplifiers (DP-EDFA) with an embedded dispersion compensation fiber are studied in this work. DP-EDFA is a cost-effective alternative for optical amplifiers, yet preserving good optical performance, mainly for use in metropolitan networks. Due to its double pass circuit, others functions beyond amplification can be inserted within the amplification circuit, increasing its capabilities and decreasing the involved cost. Considering that dispersion compensation is very critical for high-speed DWDM systems operating with standard single mode fiber, a timely topic of investigation concerns the embedding of the high insertion loss DCFs (dispersion compensating fibers) into optical amplifier configurations. Experimental studies are conducted first showing the advantages and impairments associated with DP-EDFAs circuits using DCFs. Next, a DP-EDFA proposed in this work is characterized in terms of gain and noise figure for several applications in multichannel and multiband network topologies. Systemic characterization in terms of bit error rate is also conducted, evaluating the performance of the proposed DP-EDFA using DCF
5
Amiard, Hudebine Gabriel. "Développement de sources lasers nanosecondes, picosecondes et femtosecondes et applications." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0024/document.
Abstract:
Cette thèse en deux parties porte sur le développement de sources lasers nano et picosecondes et leurs applications. La première partie présente l'étude, et la réalisation d'une chaîne amplificatrice laser nanoseconde pour l'allumage de turbomoteurs. Après avoir présenté les performances et l'évolution de cette chaîne seront présentes les résultats des campagnes d'essais réalisées sur une chambre de combustion sur un banc d'essai à l'ONERA dans des conditions de basses températures et de basses pressions. La deuxième partie de cette thèse traite du développement d'un oscillateur paramétrique optique (OPO) nécessaire pour accorder en longueur d'onde dans l'infrarouge un laser impulsionnel picoseconde ou femtoseconde à haute cadence et forte puissance moyenne. Après avoir présenté la cavité de l'OPO ainsi que ses performances, nous détaillerons la capacité de cet OPO à générer des impulsions femtoseconde comprimées à partir d'impulsions pompe présentant un étirement temporelThis two-part thesis focuses on the development of nano and picosecond laser sources and their applications. The first part presents the study, and the realization of a nanosecond laser amplifier chain for the ignition of turboshaft engines. After the repport of the performances and the evolution of this amplifier chain will be presented the results of the tests carried out on a combustion chamber on a test bench at ONERA under low temperatures and low pressures conditions. The second part of this thesis deals with the development of an optical parametric oscillator (OPO) in order to tune in the infrared the wavelength of a pulsed picosecond or femtosecond laser at high cadency and high average power. After presenting the OPO cavity and its performance, we will detail the ability of this OPO to generate compressed femtosecond pulses from pump chirped pulses
6
Michel, David Daniel. "Linear-cavity tunable fibre lasers employing an Opto-VLSI processor and a MEMS-based device." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2012. https://ro.ecu.edu.au/theses/520.
Abstract:
This thesis proposes and demonstrates experimentally two novel linear-cavity tunable fibre lasers employing an erbium-doped fibre (EDF) in conjunction with an Opto- VLSI processor and a MEMS-based device for wavelength selection. The Opto-VLSI processor and the MEMS-based device along with an optical collimator, a Bragg grating plate and an optical lens, enable the realisation of an optical filter for continuous tuning of wavelengths over the amplified spontaneous emission (ASE) range of the EDF. We also propose the use of a section of un-pumped EDF as a saturable absorber (SA), which suppresses noise spikes caused by the high optical pumping power. Experimental results show that by optimising a length of the SA a single wavelength, high power laser signal can be achieved. In addition, we experimentally demonstrate that the performance of the proposed linear-cavity tunable fibre lasers is better than that of ring-cavity tunable laser counterparts. Specifically, we show that linear-cavity based tunable fibre lasers can achieve higher output power, a larger side mode rejection ratio (SMRR) and narrower laser linewidth than ring-cavity tunable fibre lasers.
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Bouyge, David. "Systèmes lasers impulsionnels compacts et dispositifs hyperfréquences accordables basés sur l'intégration de composants MEMS." Limoges, 2007. https://aurore.unilim.fr/theses/nxfile/default/ac1d8e2a-01a5-4522-a2a7-f571790878dc/blobholder:0/2007LIMO4054.pdf.
Abstract:
Malgré le grand intérêt suscité par l’intégration de composants opto-électro-mécaniques (MOEMS) dans des systèmes optiques peu d’expérimentations concernant leur capacité à produire des impulsions optiques brèves sont développées. C’est donc dans cette direction que nous avons orienté nos travaux. Ce manuscrit dresse tout d’abord l’état de l’art sur les composants MOEMS puis présente les divers modes de fonctionnement des systèmes lasers impulsionnels. Le développement des MOEMS est exposé à travers les étapes de conception, d’optimisation du procédé de fabrication et de caractérisation. Nous démontrons ensuite le déclenchement actif de lasers à fibre basés sur l’intégration active de MOEMS. Nous présentons la réalisation d’un système laser multilongueur d’onde qui exploite l’achromaticité des micromiroirs pour la génération de radiations accordables dans le spectre visible. Enfin, nous étudions le développement de filtres réjecteurs de bande multipôles accordablesIn spite of the large interest provoked by the integration of Micro-Opto-Electro-Mechanical-System (MOEMS) in optic systems, not enough experimentation concerning their capacity to produce short optic impulsions is developed. It is therefore in this direction that we orientated our jobs. First, this manuscript raises the state of art on MOEMS micro-mirrors and then introduces various kinds of pulsed laser systems regimes. The development of MOEMS is displayed across stages of conception, optimization of technology and characterization. We demonstrate a simple technique to produce active Q-switching in various types of fiber amplifiers by active integration MOEMS. We present the realization of a multiwavelength laser system which exploits the achromaticity of micro-mirrors for the generation of tunable radiations in the visible spectre. Finally, we study the development of tunable multipole reject band filters
8
Audo, Frédéric. "Opto-alimentation et transmission de données par fibre optique pour les observatoires de fond de mer." Phd thesis, Université de Bretagne occidentale - Brest, 2012. http://tel.archives-ouvertes.fr/tel-00782502.
Abstract:
Ce mémoire de thèse est consacré à l'étude d'une liaison tout-optique longue de 10 km dédiée à l'extension d'un observatoire câblé de fond de mer existant afin d'atteindre de nouvelles zones d'exploration. Les travaux de recherche qui y sont rapportés démontrent la faisabilité de cette liaison tout-optique entre un instrument déporté et une station terrestre avec une seule fibre optique longue de 10 km, qui transmet simultanément la puissance, nécessaire à l'alimentation de l'instrument (quelques centaines de milliwatts), et des données bidirectionnelles en temps réel.Le contexte de cette thèse est présenté au travers d'un état de l'art sur les observatoires câblés et sur la puissance sur fibre. Le choix de la fibre unique et la présence de fortes puissances optiques complexifient la mise en oeuvre de cette extension tout-optique, et sont à l'origine de l'apparition d'interactions entre l'énergie optique dédiée à l'alimentation (@1480 nm) et les données échangées (@1550 nm). Tout au long de ce document, les choix technologiques retenus sont argumentés et les effets optiques non linéaires tels que les diffusions Raman, Brillouin, Rayleigh, l'Émission Spontanée Amplifiée (ASE) sont décrits, modélisés et analysés expérimentalement. L'extension tout-optique proposée a été caractérisée à la fois en régimes statique et dynamique par des mesures du bilan de liaison, du rapport signal à bruit (SNR) et du taux d'erreur binaire (BER). Les résultats obtenus montrent la possibilité de fournir 160 mW électrique à l'instrument déporté en utilisant une source optique continue de 33 dBm sans dégrader excessivement les données bidirectionnelles transmises simultanément (BER<10-7).
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Weeda, Jocelyn R. "Cultivating the Fire With(In): Teacher's Resistance in an Age of Corporate Reform." Miami University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=miami1407193226.
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Hallak, Elwan Hamza. "Systèmes optiques dédiés à la 5° génération de réseaux sans fils (5G)." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAT047/document.
Abstract:
Cette thèse concerne le développement de futurs appareils, systèmes et réseaux prenant en charge l’internet haute vitesse, sans fil 5éme g´enération (5G). La demande de débit très élevé nécessite une bande passante suffisante, et ainsi la bande de fréquence millimetrique (mm-wave) a beaucoup d’intérêt. Un certain nombre de technologies devront converger, coexister et interagir, et surtout, coopérer, si cette vision doit être efficace et rentable. Le concept principal de cette de 5G est l’intégration de réseaux de fibre optique et Les réseaux radio grâce à la technologie Radio-sur-Fibre (RoF) aux fréquences d’onde millimetriques, pour fournir des services à large bande passante et permettre des réseaux évolutifs et gérables sans structure d’interface très complexe et multiples protocoles superposés.Dans cette thèse, les systèmes de communication RoF à ondes millimetriques sont théoriquement étudiés et démontrés expérimentalement pour étudier les altérations du système. Le travail présenté dans cette thèse est axé sur le bruit optique représenté par le bruit de phase et d’intensité induit par la source optique et la dispersion chromatique introduite par la fibre optique. Le bruit optique est analysé et mesuré pour différentes techniques de génération optique. Deux dispositifs différents de conversion, un mélangeur et un détecteur d’enveloppe sont, appliqués pour le traitement du signal et pour décorréler la phase et le bruit d’intensité. Nous souhaitons souligner que cette étude et le modèle peuvent s’appliquer à tout type de système de génération optique hétérodyne et à toute gamme de fréquences. La corrélation entre les modes optiques en peigne à fréquence optique est examinée pour montrer l’impact de la dispersion chromatique. Cette thèse présente la distribution d’énergie des ondes millimetriques et son influence sur la portée des fibres et la façon dont l’effet de dispersion chromatique sur le réseau RoF depend des paramètres de dispersion. Ensuite, cette thèse démontre comment la décorrélation de la phase optique induite par la dispersion chromatique entraîne un bruit de partition de modes dans les réseaux de communication RoF à ondes millimétriques.Lors de la transmission de certains types de données sur le système, les résultats démontrent l’impact du bruit optique et de la dispersion chromatique sur le qualité du signal. Les résultats de simulation sont présentés et sont en très bon accord avec les résultats expérimentaux. La grandeur du vecteur d’erreur evaluée par en processus en ligne montre l’impact des altèrations du système sur les performances du système. Le débit de données et l’évolution du système présentée sont en conformité avec les normes de communication comme à ondes millimétriquesThis thesis is for the development of future devices, systems and networks supporting the 5th Generation (5G) high-speed wireless internet. The demand for very high bit rate requires a sufficient large bandwidth, and therefore Millimeter-Wave (mm-wave) frequency band has a lot of interest. Several number of technologies will need to converge, co-exist and interoperate, and most importantly, cooperate, if this vision is to be efficiently and cost-effectively realized. The main concept within this next 5G is the integration of optical fiber networks and radio networks through Radio-over-Fiber (RoF) technology at mm-wave frequencies, to provide high-bandwidth front/backhaul services and enable scalable and manageable networks without a highly complex interface structure and multiple overlaid protocols.In this thesis, the mm-wave RoF communication systems are theoretically studied and experimentally demonstrated to investigate the system impairments. The work presented in this thesis is focused on optical noise represented by phase and intensity noise induced by optical source and chromatic dispersion introduced by optical fiber. The optical noise is analyzed and measured for different optical generation techniques. Two different down-conversion stages, mixer and envelope detector, are applied for signal processing and to decorrelate phase and intensity noise. We would like to highlight that this study and the model can be applicable toany kind of optical heterodyne generation system and any frequency range. The correlation among optical modes in optical frequency comb is examined to show the impact of chromatic dispersion. This thesis also exhibits the mm-wave power distribution over fiber span and how the chromatic dispersion effect on the RoF network is modified by varying dispersion parameters. Then, this thesis demonstrates how the optical phase decorrelation induced by chromatic dispersion results in mode partition noise at mm-wave RoF communication networks.When transmitting some types of data over the system, the results demonstrate the impact of optical noise and chromatic dispersion on the signal quality. The simulation results are presented and are in very good agreement with experimental results. The error vector magnitudethrough online process shows the impact of the system impairments on the system performance. The data rate and system evolution are compliance with communication standards at mm-wave
Books on the topic "OPO Fibre":
1
Zeller, Ludwig. The eye on fire: Poems, September 1998-March 1999 = Imágenes en el ojo llameante : septiembre 1998-marzo 1999. Victoria, B.C: Ekstasis Editions, 2007.
2
W, Smith D., ed. Optical network technology. London: Chapman & Hall, 1995.
3
Saleh, Bahaa E. A. Fundamentals of photonics. 2nd ed. Hoboken, N.J: Wiley Interscience, 2007.
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Ramaswami, Rajiv. Optical networks: A practical perspective. 2nd ed. San Francisco: Morgan Kaufmann Publishers, 2002.
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Translator, Ludwig Zeller; A. F. Moritz;. The Eye on Fire (Imagenes en el ojo llameante. Ekstasis Editions, 2007.
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Steigmann, David J. Fiber symmetry. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198567783.003.0005.
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Gowar, John. Optical Communication Systems (Optoelectronics). 2nd ed. Prentice Hall, 1993.
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Gowar, John. Optical Communication Systems (Optoelectronics). Prentice Hall, 1993.
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Cheng, Russell. Embedded Distributions: Two Numerical Examples. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198505044.003.0007.
Abstract:
This chapter illustrates use of (i) the score statistic and (ii) a goodness-of-fit statistic to test if an embedded model provides an adequate fit, in the latter case with critical values calculated by bootstrapping. Also illustrated is (iii) calculation of parameter confidence intervals and CDF confidence bands using both asymptotic theory and bootstrapping, and (iv) use of profile log-likelihood plots to display the form of the maximized log-likelihood and scatterplots for checking convergence to normality of estimated parameter distributions. Two different data sets are analysed. In the first, the generalized extreme value (GEVMin) distribution and its embedded model the simple extreme value (EVMin) are fitted to Kevlar-fibre breaking strength data. In the second sample, the four-parameter Burr XII distribution, its three-parameter embedded models, the GEVMin, Type II generalized logistic and Pareto and two-parameter embedded models, the EVMin and shifted exponential, are fitted to carbon-fibre strength data and compared.
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Solymar, Laszlo. Getting the Message. 2nd ed. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198863007.001.0001.
Abstract:
Laszlo Solymar’s book is quite unique in the sense that it is the only one that covers all the major developments in the history of telecommunications for the past 4,000 years, like fire signals, the mechanical telegraph, the electrical telegraph, telephony, optical fibres, fax, satellites, mobile phones, the Internet, the digital revolution, the role of computers, and also some long-forgotten technologies like news broadcasting by a devoted telephone network. It tells the technical aspects of the story but also how it affects people and society; e.g.it discusses the effect of the electric telegraph on war and diplomacy, how thanks to the telegraph Kitchener could preserve the Cairo-to-Cape Town red band for the British Empire, or more recent events like the effect of deregulation upon the monopoly of the American Telephone and Telegraph Company (AT&T). A number of anecdotes are told, e.g. how one murderer was caught by telegraphy when he arrived at Paddington Station and how another murderer was caught by wireless telegraphy when tried to escape by boat from Britain to Canada. The last chapter is concerned with the future: how the future was envisaged in the past and how we imagine the future of telecommunications now.
Book chapters on the topic "OPO Fibre":
1
Protopopov, Vladimir. "Fiber Optics." In Practical Opto-Electronics, 219–30. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-04513-9_7.
2
Vickers, Les, Arie van Riessen, and William D. A. Rickard. "Fire Resistance of OPC and Geopolymers." In SpringerBriefs in Materials, 99–110. Singapore: Springer Singapore, 2014. http://dx.doi.org/10.1007/978-981-287-311-8_6.
3
Wu, Teng, Xiang Peng, Jingbiao Chen, and Hong Guo. "Fiber-Coupled OPM in Purely Coil-Shielded Environment." In Flexible High Performance Magnetic Field Sensors, 161–77. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-05363-4_9.
4
Bannister, Sir Roger. "Disorders of muscle." In Brain and Bannister’s Clinical Neurology, 459–84. Oxford University PressNew York, NY, 1992. http://dx.doi.org/10.1093/oso/9780192619891.003.0021.
Abstract:
Abstract A voluntary muscle is composed of muscle fibres, each of which is a multinucleated cell, consisting of contractile substance with a sarcolemma and its nuclei, and a· motor end-plate in which the nerve fibre terminates. The lower motor neuron ends in relation with a bundle of 150 or more muscle fibres. Skeletal muscle fibres are not homogeneous and contain two distinct types of fibre. The type I fibre is smaller and has a high concentration of enzymes which are concerned with aerobic metabolism. The type II fibre is large with coarse myofibrils and has a higher concentration of glycogen and of enzymes which are concerned with anaerobic metabolism.
5
Vincent, Julian F. V. "Composites." In Biomechanics Materials, 57–74. Oxford University PressOxford, 1992. http://dx.doi.org/10.1093/oso/9780199632237.003.0004.
Abstract:
Abstract Composite materials are composed of stiff strong fibres, plates, or particles (the discontinuous phase) in a relatively compliant matrix (the continuous phase). Composites with ceramic materials (CaCO3, hydroxyapatite, etc.) as the discontinuous phase are covered in Chapter 3. In other biological compo sites the discontinuous phase can be protein (as in skin and keratin) or polysaccharide (arthropod cuticle, plants). The chemical nature is not impor tant for mechanical analysis although bond energy and density are important. In order to provide reinforcement, the fibres have to be sufficiently long: maximum reinforcement is obtained with infinitely long fibres; collagen fibres in echinoderms have an aspect ratio of over 5000. The fibre takes forces from the matrix through shear forces developed at the fibre-matrix interface. This transfer of force occurs along a length of fibre determined by the relative moduli of matrix and fibre, the conditions at the interface, and the diameter of the fibre. In order to reinforce effectively, the length of the fibre has to be at least twice this transfer length. At lesser lengths the fibres reinforce less effectively, acting as filler particles. The aim in testing composite materials should be to integrate the morphology of the material (such as the amount, aspect ratio, and orientation of fibres) with the mechanical properties of the whole material and of the separate phases. Harris (1) and Piggott (2) are good introductions to definitions and analysis. Although not strictly composites, cellular materials have been included in this chapter because they are often constructed of composite materials (3).
6
Solymar, Laszlo. "Optical Fibres Revisited." In Getting the Message, 295–300. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198863007.003.0018.
Abstract:
A history of the use of single- and multimode fibres in optic fibres is provided. Wavelength division multiplex is introduced, The same fibre can carry hundreds of wavelength bands. The longest stretch of optical fibre line is about 10,000 km. The greatest capacity achieved has been in the petabit/s range for a single cable with 32 cores, each one having 16 wavelength channels capable of carrying 680 Gb/s each. The ‘last mile’ problem still has not been solved in Britain. The relative advantages of satellites and optical fibres are discussed. Fibres working on different physical principles, e.g. holey fibres, have also been invented.
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Solymar, Laszlo. "Optical Communications: The Beginning." In Getting the Message, 211–24. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198863007.003.0012.
Abstract:
The first efforts by Alexander Graham Bell at optical communications by incoherent light are discussed. Those were very inefficient at the time but after the invention of the laser it was only a question of time when coherent optical communication will dominate the communications scene The beginning was slow because propagation both in air and in fibre waveguide was too large. Enormous efforts by the Corning Glass Works brought down the attenuation to a figure as low as a few dbs per kilometre making some further applications feasible. The next break-through was the invention of the fibre amplifier enabling the erection of long relay-free lines (maybe up to 10,000 km) possible range of applications was greatly extended by the invention of the fibre amplifier. Coherent light propagation in thin, single-mode fibres is discussed a very thin fibre is discussed. It is shown that an optical fibre can carry an enormous number of communication channels. The laser was invented just in time to help produce the signals, and it also became possible to produce pure enough glass fibres in which an optical signal could propagate with low attenuation. The invention of erbium-doped fibre amplifiers allowed them to be spread all over the world, including large number of lines under the oceans.
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Brooker, Geoffrey. "Optical fibres." In Modern Classical Optics, 311–23. Oxford University PressOxford, 1992. http://dx.doi.org/10.1093/oso/9780198599647.003.0014.
Abstract:
Abstract The main application of optical fibres (now) is in optical communication. Telephone traffic between exchanges is almost all carried by optical fibre, and in many towns and cities a fibre passes every house entrance.When a signal is to be conveyed, it must be encoded in some way (modulated) onto light or some other wave. There is a range of frequencies, the bandwidth Δν, that is required for transmission of the signal; and that bandwidth is proportional to the rate at which information is to be transmitted. Conversely, the rate at which information may be carried along an optical fibre is determined by the range of frequencies that it is practical to transmit along the fibre, given the properties of the fibre and of the associated light sources and detectors.
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Hasegawa, Akira, and Yuji Kodama. "Reshaping Of Solitons And Concept Of Guiding Centre (Average) Solitons." In Solitons in Optical Communications, 110–29. Oxford University PressOxford, 1995. http://dx.doi.org/10.1093/oso/9780198565079.003.0007.
Abstract:
Abstract A major unsatisfactory feature of the long-distance propagation of a soliton in fibres is the effect of fibre loss. The authors have proposed several methods to compensate for this effect (Hasegawa and Kodama 1982; Kodama and Hasegawa 1982, 1983; Hasegawa 1983, 1984). Among these, the concept of Raman amplification using the fibre Raman gain itself (Hasegawa 1983, 1984) was found to reshape the soliton successfully in experiments by Mollenauer et al. (1985). The effect of repeated Raman amplification was further studied numerically by Mollenauer et al. (1986) and the first successful long distance all optical transmission was demonstrated by Mollenauer and Smith (1988). However, the original idea of simple optical amplification (Kodama and Hasegawa 1982) became feasible because of the discovery of the erbium doped fibre amplifier (Mears et al. 1987; Desurvire et al. 1987). Reshaping solitons by the erbium-doped fibre amplifier was first tested and successfully demonstrated by Nakazawa et al. (1989). As a possible alternative to the erbium-doped amplifier, the use of lumped parametric amplifier has been also proposed by Yuen (1992) (see also Kutz et al. (1993)).
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Schedl, Paul, and Frank Grosveld. "Domains and boundaries." In Chromatin Structure and Gene Expression, 172–96. Oxford University PressOxford, 1995. http://dx.doi.org/10.1093/oso/9780199635764.003.0009.
Abstract:
Abstract The very large genomes found in many higher eukaryotes must be condensed into a relatively small volume inside the nucleus. This is accomplished by packaging the DNA into a complex, multi-level nucleoprotein structure, chromatin. At the first level of organization the DNA is assembled into a beads-on-a-string nucleosome array, the 10 nm fibre visualized by electron microscopy (see Chapter 1). In the second level of organization, the 10 nm fibre is coiled into a 30 nm fibre. While this transition is thought to be facilitated by Hl binding (1), the precise organization of the nucleosomes is not completely resolved. In one widely accepted model (2, 3) they are coiled into a fairly homogeneous solenoid-like structure, six nucleosomes per turn. Recently, some electron microscopy studies have suggested that the principle building block of the 30 nm fibre is a di-nucleosomal unit that appears to zigzag across the fibre axis, giving a much more irregular and potentially dynamic structure (4). Whichever model is correct, the 10 nm and 30 nm fibres most certainly coexist in the interphase nucleus, with specific regions of the chromosome undergoing transitions from one state to the other, presumably as a consequence of transcriptional activity or DNA replication and recombination (see 5-9). Additional levels of organization above the 30 nm fibre are required to fit the DNA inside the interphase nucleus and to achieve the even higher levels of DNA compaction observed in mitotic chromosomes. This higher order folding of the 30 nm fibre is very poorly understood, and there is still a great deal of controversy about the principles governing the 3-D orgnization of chromatin inside the nucleus.
Conference papers on the topic "OPO Fibre":
1
Van der Westhuizen, Gys J., and Johan Nilsson. "All-fibre OPO system for visible wavelengths." In 2011 International Quantum Electronics Conference (IQEC) and Conference on Lasers and Electro-Optics (CLEO) Pacific Rim. IEEE, 2011. http://dx.doi.org/10.1109/iqec-cleo.2011.6194084.
2
Date, Aditya, Sourabh Mukhopadhyay, and Prasanta K. Datta. "Stability of Passive Mode-locking of OPO with Temporal Walk Off." In International Conference on Fibre Optics and Photonics. Washington, D.C.: OSA, 2012. http://dx.doi.org/10.1364/photonics.2012.tpo.9.
3
A, Aadhi, Varun Sharma, Apurv Chaitanya Nellikka, and G. K. Samanta. "Multi GHz Repetition Rate Airy Beam Radiation In Higher-harmonic Fractional Cavity OPO." In International Conference on Fibre Optics and Photonics. Washington, D.C.: OSA, 2016. http://dx.doi.org/10.1364/photonics.2016.tu2d.4.
4
Mahnke, Peter, Martin Wirth, and Andreas Fix. "OPO resonator length stabilisation for injection seeding using fibre coupled heterodyne detection." In 2008 Conference on Lasers and Electro-Optics (CLEO). IEEE, 2008. http://dx.doi.org/10.1109/cleo.2008.4552303.
5
O'Driscoll, Elizabeth J., and Malcolm A. Watson. "Design and construction of a photonic-fibre-pumped OPO for active sensor systems." In European Symposium on Optics and Photonics for Defence and Security, edited by David H. Titterton. SPIE, 2004. http://dx.doi.org/10.1117/12.578260.
6
Persijn, S. T., A. K. Y. Ngai, F. J. M. Harren, I. D. Lindsay, P. Gross, B. Adhimoolam, and K. J. Boller. "Fast-Scanning Fibre-Amplified Diode Laser Pumped cw OPO for Sensitive, Multi-Component Trace Gas Detection." In 2007 European Conference on Lasers and Electro-Optics and the International Quantum Electronics Conference. IEEE, 2007. http://dx.doi.org/10.1109/cleoe-iqec.2007.4386078.
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Reid, D. T., P. Loza-Alvarez, M. Ebrahimzadeh, W. Sibbett, H. Karlsson, and F. Laurell. "Femtosecond Pulse Compression by Second-Harmonic Generation in Aperiodically-Poled KTP." In The European Conference on Lasers and Electro-Optics. Washington, D.C.: Optica Publishing Group, 1998. http://dx.doi.org/10.1364/cleo_europe.1998.cwh5.
Abstract:
By fabricating a periodically-poled frequency-doubling crystal with a linearly-varying grating period one can define the position in the crystal at which any frequency is converted to its second harmonic. Using this method stretched pulses from an erbium-doped fibre laser were recompressed in aperiodically-poled lithium niobate [1]. In our work we describe the use of an aperiodically-poled crystal of KTP [2] to frequency-double and compress the chirped femtosecond output pulses from an optical parametric oscillator (OPO) running at a wavelength of 1.25 µm.
8
Köhler, B., J. Dörring, A. Nebel, and R. Wallenstein. "Noncritically phase-matched femtosecond and picosecond CsTiOAsO4 (CTA) optical parametric oscillator." In The European Conference on Lasers and Electro-Optics. Washington, D.C.: Optica Publishing Group, 1996. http://dx.doi.org/10.1364/cleo_europe.1996.cthn2.
Abstract:
Optical parametric oscillators (OPOs) are known to be powerful devices for the generation of tunable ultrashort light pulses. The Ti:sapphire laser pumped CTA-OPO allows noncritical phase matching in the near infrared (1.32.3 µm) and thus generates ps- or fs pulses at the two important wavelengths for optical fiber applications.
9
Südmeyer, T., J. Au Aus der, R. Paschotta, U. Keller, P. G. R. Smith, G. W. Ross, and D. C. Hanna. "Femtosecond fiber-feedback OPO." In Advanced Solid State Lasers. Washington, D.C.: OSA, 2001. http://dx.doi.org/10.1364/assl.2001.mf6.
10
Jin, Yan, Jizhao Zang, Travis Briles, David Carlson, and Scott Papp. "Parametric Oscillators and Soliton Combs in Bandgap-detuned Nanoresonators." In Optical Fiber Communication Conference. Washington, D.C.: Optica Publishing Group, 2024. http://dx.doi.org/10.1364/ofc.2024.w3d.3.
Abstract:
We report controllable generation of OPO lasers and soliton microcombs by manipulating nonlinear dynamics with nanophotonic bandgaps. By excitation detuned from bandgap modes, we realize wide-tunability, low-threshold-power and high-conversion-efficiency lasers.
Reports on the topic "OPO Fibre":
1
Cuello, Xavier. ¿Fiebre del oro en el Ripollés (Gerona)? ILUSTRE COLEGIO OFICIAL DE GEOLOGOS, January 2017. http://dx.doi.org/10.21028/xcv.2017.01.30.
2
Nevøy, Anne, and Stein Erik Solbø Ohna. Spesialundervisning – bilder fra skole-Norge: En studie av spesialundervisnings dynamikk i grunnopplæringen. University of Stavanger, June 2014. http://dx.doi.org/10.31265/usps.226.
Abstract:
Formålet med denne studien er å utforske dette sammensatte og motstridende nåtidsbildet. Vi er på jakt etter spesialundervisningens dynamikk i grunnskolen og i videregående opplæring. Det overordna forskningsspørsmålet er: Hvordan kan spesialundervisningens dynamikk i grunnopplæringen forklares og forstås? To delspørsmål leder inn i studien: • Hvordan beskriver faggruppene i skolen økningen i spesialundervisning, og hvilke forhold mener de bidrar til økningen? • Hvilke mønstre framkommer i beskrivelsene av skolens spesialundervisning, hvilke krefter er i spill og hvilken innvirkning har disse på omfanget av spesialundervisning? Studiens empiriske materiale er framkommet gjennom intervju med fire faggrupper i skolen; lærere, rektorer, PPT og skoleeier. Disse intervjuene er gjennomført høsten 2011 i seks kommuner og to fylkeskommuner. Erfaringer og synspunkt fra faggruppene i disse kommunene og fylkeskommunene representerer et variert bilde av skole-Norge, fra nord til vest og øst, og faggruppenes meninger gir et bredt grunnlag for å utvikle kunnskap om spesialundervisningen i grunnopplæringen. Studien er konsentrert om faggruppene i skolene sine perspektiv på spesialundervisning. Spørsmål om hva elever og foreldre mener om spesialundervisning, inngår ikke i denne sammenhengen. For-målet her er å få del i meninger og refleksjoner til skolens faggrupper og det er derfor valgt en kvali-tativ tilnærming basert på fokusgruppeintervju og kvalitative analyser. Siktemålet er å forstå en kompleks del av skolens virksomhet. Studien tar derfor ikke opp kvantitative størrelser ved skolens spesialundervisning, som effekt av spesialundervisningen for enkeltelever eller omfang av spesialun-dervisning for ulike «vanskegrupper». Presentasjonen av studien er strukturert i seks delkapitler. Innledningsvis, i kapittel 1 presenteres studiens formål og forskningsspørsmålene. I kapittel 2, Inkluderende opplæring og spesialundervis-ning utdypes studiens teoretiske innramming. I kapittel 3 presenteres Forskningsprosessen. Studiens empiriske del består av to analyser. Disse presenteres i kapittel 4 og 5. I kapittel 4, Skolens spesialun-dervisning – et innenfra perspektiv fra fagfolk i åtte kommuner/fylkeskommuner presenteres en em-pirinær analyse av datamaterialet. I kapittel 5, Spesialundervisning – skolens svar på samtidens ut-fordringer vendes blikket fra et innenfra til en utenfra perspektiv. Analysen henter fram generelle forhold ved skolens spesialundervisning og hvordan disse former et samvirkende mønster. I kapittel 6, Spesialundervisning i den inkluderende fellesskolen, sammenfattes studiens svar på spørsmålet om hvordan spesialundervisningens dynamikk i grunnopplæringen kan forklares og forstås.
3
Njå, Ove, and Kirsti Russell Vastveit. Norske kommuners planlegging, gjennomføring og bruk av risiko- og sårbarhetsanalyse i forbindelse med samfunnssikkerhetsarbeidet. University of Stavanger, October 2016. http://dx.doi.org/10.31265/usps.164.
Abstract:
I prosjektet; «Helhetlig ROS-analyse i norske kommuner» analyserer vi hvordan kommuner utvikler, bruker og oppdaterer ROS-analyser og risikoforestillinger i sitt samfunnssikkerhetsarbeid. Det legges vekt på hvordan kommuner integrerer ROS-arbeidet og risikoforestillinger i eksisterende plan- og arbeidsprosesser. Hvilke utfordringer opplever kommunene i dette arbeidet? Etter å ha jobbet med risiko og sikkerhet i mer enn 20 år, og en vesentlig del av disse opp mot kommuner, er det etter vårt syn et gjennomgående trekk at kommunalt ansatte som jobber med sikkerhet og beredskap har stor skepsis til akademikere på dette feltet. Den teoretiske «verden» er ikke i stand til å kommunisere med den praktiske og vice versa. Denne utfordringen mener vi står sterkt også i dag, og dermed ble det i prosjektet viktig å finne ut hvordan begrepene ble brukt i kommunene. Hvor kritiske er begrepene for omfanget av bruken av analysene? Står vi ved et markant skille nå med innføring av ny veileder for helhetlig ROS-analyse i kommuner? Eller, er arbeidet omkring samfunnssikkerhet og beredskap fastnet i en praksis uten påvirkning fra ROS-analyse? Datamateriale fra 26 kommuner er inkludert i studien. Kommunene dekker alle landsdelene og de har varierte demografiske og geografiske profiler. Blant deltagerne er kommuner med storulykkesindustri, større bykommuner, mindre øykommuner og grensekommuner. Opptil fem personer med ulikt ansvar for samfunnssikkerhets- og beredskapsarbeidet er intervjuet i hver kommune. En viktig del av prosjektet er forholdet mellom ROS-analyser på ulike forvaltningsnivåer, hvordan ROS-analysene kommuniserer risikoforestillinger og hvordan kommunene kan bygge på og hente innspill fra hverandre i ROS-analysearbeidet. Siden 2010 har Lov om kommunal beredskapsplikt, sivile beskyttelsestiltak og Sivilforsvaret (sivilbeskyttelsesloven) og underliggende Forskrift om kommunal beredskapsplikt stilt krav til kommunenes ROS-analyse og samfunnssikkerhetsarbeid i stort. Likevel er det ikke opplagt hva det innebærer. Forskriften snakker om begreper og konsepter som; - Jobbe systematisk og helhetlig med samfunnssikkerhet; - Forankring i kommunestyret; - Eksisterende og fremtidige risiko- og sårbarhetsfaktorer; - Særlige utfordringer; - Langsiktige mål, strategier, prioriteringer og plan for oppfølging av samfunnssikkerhets- og beredskapsarbeidet; - Vurdere forhold som bør integreres i planer og prosesser; og - Overordnet beredskapsplan. Det stiller store krav til kommunens ansattes kunnskap og kompetanse til å fortolke hva alle disse konseptene skal bety for kommunen og hvordan ansatte skal jobbe med kravene. Her ligger kjernen av vår studie. Studien vår viser at det legges betydelig med ressurser og arbeid ned i kommuners helhetlige ROS-analyser, samfunnssikkerhets og beredskapsarbeid. Risikoinformert styring og risikotenkning er en krevende filosofi, hvor det forutsettes at de ansatte med ansvar for kommunens systemer og samfunnssikkerhets- og beredskapsarbeidet har høy kompetanse på området. I kommunene som deltok i studien synes det å være enklere for kommunene å konkretisere hvordan de arbeidet med beredskap enn med samfunnssikkerhet. Kommunene hadde i varierende grad oversikt over hvordan beredskapsarbeidet var satt i system på tvers av etater. Materialet ble analysert ut fra fire forhold: - Begrepsforståelser og bruk av begreper for å uttrykke samfunnssikkerhet - Planlegging og gjennomføring av ROS-analyseprosesser - Presentasjon av resultater fra ROS-analysearbeidet - Implementering av analyseresultatene i kommunens aktiviteter Datamaterialet viser at kommunene og de fleste respondentene våre er i liten grad bekymret over begrepene de bruker. I hovedsak er det risiko, ROS-analyse (eller andre koplinger av ROS), hendelser, akseptkriterier, beredskap, kriseplaner og tiltak som er konseptene i bruk. Usikkerhet var et begrep som fulgte med, men det var i liten grad reflektert over utover at det var en egenskap med hele ROS-analyseprosessene. Samfunnssikkerhet, ytelse av beredskapstiltak, sårbarhet, resiliens, barrierer, system er begreper som får lite eller ingen omtale i kommunenes befatning med samfunnssikkerhet og beredskap. Kommunene er veldige instrumentelle i arbeidet med å utvikle produktene (helhetlig) ROS-analyse og beredskap- og kriseplaner. Beslutningsprosessene som den helhetlige ROS-analysen er en del av, trekkes ikke frem som førende for hvordan ROS-analyser og samfunnssikkerhetsarbeidet gjøres. Fylkesmannen sin rolle som pådriver, rådgiver og tilsynsmyndighet var for de aller fleste kommunene beskrevet med positive fortegn. Alle analysene vi har hatt tilgang til er utført som grovanalyser (hazid-gjennomganger, scenariobeskrivelser, gruppediskusjoner), men med relativt små variasjoner innenfor hvordan risiko måles og uttrykkes. Enkelte kommuner inspireres av innholdet i FylkesROS-analyse eller Nasjonalt Risikobilde, mens andre har et større fokus på lokale forhold og hendelser. I forbindelse med bruk av tiltak fra helhetlig ROS-analyse var det en klar trend at kommunene synes det var vanskelig å sikre implementering av tiltak. Dette skyldes blant annet at det var utfordrende å sikre at den ansvarlige etat tok ansvar for tiltak, at beredskapskoordinatorer ikke anså tiltak som skulle implementeres i enkeltetater som sitt ansvar og at kommunene i mange tilfeller ikke hadde midler til gjennomføring av tiltak. Problemet kan trolig også spores til at helhetlig ROS-analyse ikke var et dokument som var i aktiv bruk i hverdagen til kommunenes ansatte, og som det i de fleste tilfeller ikke ble laget aksjonsplaner for å følge opp. På tiltakssiden var det også tydelig at flere kommuner gjorde det vanskelig for seg selv, ettersom de beskrev svært generelle tiltak i rapportene sine, tiltak som egentlig var på plass i den ansvarlige etat og som var dekket av andre internkontrollrutiner, eller som andre offentlige etater var ansvarlige for. Kommunene i prosjektet hadde i varierende grad koblet beredskapsplanene sine opp mot de helhetlige ROS-analysene. En annen utfordring i forbindelse med «bruk» til beredskapsplanlegging var at kommunene ikke var sikre på hvordan dette skulle tolkes. Skulle man lage øvelser basert på hendelsene som var brukt i helhetlig ROS-analyse, skulle det lages tiltakskort som passet til scenarioene i helhetlig ROS-analyse? Enkelte kommuner hadde inkludert hendelser fra helhetlig ROS-analyse i beredskapsplanverket sitt, mens andre hadde fokusert mer på felles kapasiteter i helhetlig ROS-analyse. Å se sammenhengen mellom helhetlig ROS-analyse og beredskapsplanlegging var et vanskelig tema for kommunene. Beredskapsanalyse og vurdering av «godheten» av beredskapstiltak er også en stor utfordring. Den største utfordringen og det viktigste funnet som har kommet fram gjennom studiet er at prinsippene i risikobasert styring er nærmest fraværende i kommunene. Funksjonelle krav til sikkerhet mangler, en levende diskusjon om samfunnssikkerhet og beredskap mangler, og analysene brukes i svært liten grad. ROS-analyse og intensjoner om risikobasert styring har vært i norske kommuner i mer enn 20 år, og basert på dette mener vi at det er kompetanse og reguleringsregimet det må gjøres noe med, heller enn å innføre nye veiledere og tilsynsaktiviteter. Ansvaret for kommunens samfunnssikkerhets- og beredskapsarbeid må knyttes opp mot spesifikk kompetanse. Det krever at kommunene endrer praksis på i den administrative ledelsen og virksomhetene som eier systemene, tjenestene og aktivitetene, så vel som i kommunikasjonen mellom administrativ og politisk ledelse når det gjelder samfunnssikkerhet og beredskap. Vi mener at politikeren fra bykommune 1 langs kysten i Nord-Norge illustrerer behovet på en betegnende måte: «Veldig få i beredskapsrådet har lest dokumentene. I vårt fylke tror jeg vi er noen av de som har kommet lengst, og det sier etter mitt skjønn sitt». «Vi må involvere oss på et mye tidligere stadium. Skaffe oss oversikt over hva som er beredskapsplanene, og hvor flaskehalsene er. Det tror jeg at jeg deler med veldig mange. Vi strykes med hårene i alt for stor grad. Vi får for mye ros.»
4
Johansson, Eva, Elisabeth Ianke Mørkeseth, Monika Röthle, Berit Tofteland, Berit Zachrisen, and Kristin Fugelsnes. Verdier i barnehagen: Mellom ideal og realiteter. University of Stavanger, March 2014. http://dx.doi.org/10.31265/usps.228.
Abstract:
Denne rapporten er skrevet på bakgrunn av prosjektet «Verdier i barnehagen» (2010-2013), et samarbeidsprosjekt om utvikling og forskning i syv barnehager. Målet har vært å studere kommunikasjon av verdier mellom voksne og barn, og samtidig å støtte opp under og utfordre de voksnes arbeid med verdier i barnehagen. De syv barnehagene i prosjektet kommer fra to ulike kommuner i Rogaland. Den ene er en bykommune, den andre en landkommune. Initiativet kom fra Universitetet i Stavanger (UiS) som våren 2010 inviterte de to kommunene til å delta i prosjektet. Prosjektet har blitt finansiert dels av kommunene og den enkelte barnehage, dels av UiS og senere NordForsk. Fem forskere, universitetslektor Kristin Fugelsnes, førstelektorene Elisabeth Ianke Mørkeseth og Monika Röthle samt universitetslektor Berit Tofteland har medvirket i alle faser av studien. De fire forskerne hadde ansvar for én eller to barnehager hver. De fulgte barnehagen ”sin” gjennom hele prosjektperioden, både i utviklingsdelen og i forskningsdelen. De har også intervjuet personalet på den avdelingen de har filmet. Professor Eva Johansson står for prosjektidé og har vært leder av prosjektet. Hun har utført de fleste intervjuene i studien. Forskergruppen har sammen kontinuerlig arbeidet med å utvikle og gjennomføre prosjektet. Ytterligere en forsker, førsteamanuensis Berit Zachrisen, kom inn høsten 2013, og har deltatt i forskergruppen og arbeidet med rapporten. Prosjektet hviler på et nært samarbeid mellom barnehageansatte og forskere. Respekt for de ansattes kunnskap har vært sentralt gjennom hele prosjektet. Det betyr at det er de ansatte i barnehagene som selv har utarbeidet mål og arbeidsmåter i forhold til de verdier som de mener er viktige i forhold til sin gruppe av barn. Forskernes rolle har vært å støtte og utfordre prosessen uten å komme med ferdige løsninger. Slik bygger prosjektet som sådan på verdier som tillit, respekt og medvirkning. Prosjektet startet høsten 2010. Arbeidet i barnehagene, både med utviklingsprosjektet og med konstruksjon av data til forskningsprosjektet, foregikk frem til våren 2012, det vil si i til sammen to barnehageår. I denne perioden arbeidet de ansatte i barnehagene med verdier på ulike måter, og forskerne støttet dette arbeidet ved å arrangere seminarer og inspirasjonsdager. Én barnegruppe i hver barnehage ble i de to årene fulgt systematisk ved hjelp av forskjellige forskningsmetoder. Denne avdelingen kaller vi heretter forskningsavdelingen. Forskernes arbeid med analyse av data og rapportskriving foregikk i hovedsak etter at prosjektet i barnehagene var avsluttet, mellom 2012 og våren 2014. I mars 2013 holdt forskerne et tilbakemeldingsseminar der foreløpige funn fra prosjektet ble presentert. Prosjektet ble i 2013 utvidet til et nordisk prosjekt, «Values education in Nordic preschools: Basis of education for tomorrow», finansiert av NordForsk og deltakende universiteter i alle de nordiske landene. Den nordiske delen av prosjektet kommer til å pågå ut 2015. Denne rapporten pretenderer ikke å fremstille sannhet, men å gi et bilde av det komplekse arbeidet med verdier som pågår i hverdagens mange møter mellom voksne og barn. Vår forhåpning er at rapporten skal leses for å gi kunnskap, inspirasjon, refleksjon og støtte i det videre arbeidet med verdier. Den er ikke en vurdering av den enkelte pedagog eller barnehage. Arbeidet med verdier er, som flere av deltakerne har sagt, et arbeid som ikke avsluttes når prosjektet gjør det; det blir aldri ferdig!