Modes Hybrides dans les Fils Quantiques Réalisés sur Niobate de Lithium en Coupe X

Dans ce papier, nous nous concentrerons sur l'influence des contraintes induites dans le cristal par le processus de fabrication des fils quantiques. Ces tensions sont responsables d'un couplage fort entre les polarisations qui confère une nature hybride aux modes se propageant et qui doit être prise en considération dans la conception des dispositifs

Near-infrared active polarimetric and multispectral laboratory demonstrator for target detection

International audienceWe report on the design and exploitation of a real-field laboratory demonstrator combining active polarimetric and multispectral functions. Its building blocks, including a multiwavelength pulsed optical parametric oscillator at the emission side and a hyperspectral imager with polarimetric capability at the reception side, are described. The results obtained with this demonstrator are illustrated on some examples and discussed. In particular it is found that good detection performances rely on joint use of intensity and polarimetric images, with these images exhibiting complementary signatures in most cases

Slow light fiber systems in microwave photonics

Slow light systems are particularly attractive for analog signal processing, since their inherent limitation to a delay-bandwidth product of 1 is less critical for analog systems such as those used in microwave photonics. We present here the implementation of two basic functions - phase shifting and true time delaying - fully optically controlled using stimulated Brillouin scattering in optical fibers. The combination of these two functions makes possible the implementation of true time delays without limitation on the microwave carrier frequency using the separate carrier tuning technique. This is illustrated by the implementation of the delaying system for the realization of a microwave tunable notch filter

Dynamic saturation in semiconductor optical amplifiers: accurate model, role of carrier density, and slow light

We developed an improved model in order to predict the RF behavior and the slow light properties of the SOA valid for any experimental conditions. It takes into account the dynamic saturation of the SOA, which can be fully characterized by a simple measurement, and only relies on material fitting parameters, independent of the optical intensity and the injected current. The present model is validated by showing a good agreement with experiments for small and large modulation indices.Comment: 9 pages, 5 figure

Theoretical Study of the Spurious-Free Dynamic Range of a Tunable Delay Line based on Slow Light in SOA

We developed a predictive model describing harmonic generation and intermodulation distortions in semiconductor optical amplifiers (SOAs). This model takes into account the variations of the saturation parameters along the propagation axis inside the SOA, and uses a rigorous expression of the gain oscillations harmonics. We derived the spurious-free dynamic range (SFDR) of a slow light delay line based on coherent population oscillation (CPO) effects, in a frequency range covering radar applications (from 40kHz up to 30GHz), and for a large range of injected currents. The influence of the high order distortions in the input microwave spectrum is discussed, and in particular, an interpretation of the SFDR improvement of a Mach-Zehnder modulator by CPOs effects in a SOA is given.Comment: 12 pages, 5 figures (8 attached figures

Broadband true time delay for microwave signal processing, using slow light based on stimulated Brillouin scattering in optical fibers

[EN] We experimentally demonstrate a novel technique to process broadband microwave signals, using all-optically tunable true time delay in optical fibers. The configuration to achieve true time delay basically consists of two main stages: photonic RF phase shifter and slow light, based on stimulated Brillouin scattering in fibers. Dispersion properties of fibers are controlled, separately at optical carrier frequency and in the vicinity of microwave signal bandwidth. This way time delay induced within the signal bandwidth can be manipulated to correctly act as true time delay with a proper phase compensation introduced to the optical carrier. We completely analyzed the generated true time delay as a promising solution to feed phased array antenna for radar systems and to develop dynamically reconfigurable microwave photonic filters. (C) 2010 Optical Society of AmericaWe acknowledge the support from the Swiss National Science Foundation through project 200020-121860 and the support from the European Union FP7 project GOSPEL.Chin, S.; Thevenaz, L.; Sancho Durá, J.; Sales Maicas, S.; Capmany Francoy, J.; Berger, P.; Bourderionnet, J.... (2010). Broadband true time delay for microwave signal processing, using slow light based on stimulated Brillouin scattering in optical fibers. Optics Express. 18(21):22599-22613. https://doi.org/10.1364/OE.18.022599S22599226131821Capmany, J., & Novak, D. (2007). Microwave photonics combines two worlds. Nature Photonics, 1(6), 319-330. doi:10.1038/nphoton.2007.89Dolfi, D., Joffre, P., Antoine, J., Huignard, J.-P., Philippet, D., & Granger, P. (1996). Experimental demonstration of a phased-array antenna optically controlled with phase and time delays. Applied Optics, 35(26), 5293. doi:10.1364/ao.35.005293Yunqi Liu, Jianliang Yang, & Jianping Yao. (2002). Continuous true-time-delay beamforming for phased array antenna using a tunable chirped fiber grating delay line. IEEE Photonics Technology Letters, 14(8), 1172-1174. doi:10.1109/lpt.2002.1022008Mørk, J., Kjær, R., van der Poel, M., & Yvind, K. (2005). Slow light in a semiconductor waveguide at gigahertz frequencies. Optics Express, 13(20), 8136. doi:10.1364/opex.13.008136Su, H., Kondratko, P., & Chuang, S. L. (2006). Variable optical delay using population oscillation and four-wave-mixing in semiconductor optical amplifiers. Optics Express, 14(11), 4800. doi:10.1364/oe.14.004800Shi, Z., & Boyd, R. W. (2009). Discretely tunable optical packet delays using channelized slow light. Physical Review A, 79(1). doi:10.1103/physreva.79.013805Morton, P. A., & Khurgin, J. B. (2009). Microwave Photonic Delay Line With Separate Tuning of the Optical Carrier. IEEE Photonics Technology Letters, 21(22), 1686-1688. doi:10.1109/lpt.2009.2031500Song, K. Y., Herr�ez, M. G., & Th�venaz, L. (2005). Observation of pulse delaying and advancement in optical fibers using stimulated Brillouin scattering. Optics Express, 13(1), 82. doi:10.1364/opex.13.000082Thévenaz, L. (2008). Slow and fast light in optical fibres. Nature Photonics, 2(8), 474-481. doi:10.1038/nphoton.2008.147Nikles, M., Thevenaz, L., & Robert, P. A. (1997). Brillouin gain spectrum characterization in single-mode optical fibers. Journal of Lightwave Technology, 15(10), 1842-1851. doi:10.1109/50.633570Loayssa, A., & Lahoz, F. J. (2006). Broad-band RF photonic phase shifter based on stimulated Brillouin scattering and single-sideband modulation. IEEE Photonics Technology Letters, 18(1), 208-210. doi:10.1109/lpt.2005.861307González Herráez, M., Song, K. Y., & Thévenaz, L. (2006). Arbitrary-bandwidth Brillouin slow light in optical fibers. Optics Express, 14(4), 1395. doi:10.1364/oe.14.001395Weiqi Xue, Sales, S., Mork, J., & Capmany, J. (2009). Widely Tunable Microwave Photonic Notch Filter Based on Slow and Fast Light Effects. IEEE Photonics Technology Letters, 21(3), 167-169. doi:10.1109/lpt.2008.2009468Sagues, M., García Olcina, R., Loayssa, A., Sales, S., & Capmany, J. (2008). Multi-tap complex-coefficient incoherent microwave photonic filters based on optical single-sideband modulation and narrow band optical filtering. Optics Express, 16(1), 295. doi:10.1364/oe.16.00029

Correction des aberrations et mise en forme spatiale d'un faisceau laser par contrôle de phase intracavité

VERSAILLES-BU Sciences et IUT (786462101) / SudocSudocFranceF

Spatial mode control of a diode-pumped Nd:YAG laser by use of an intracavity holographic phase plate

International audienceWe present a new method of realizing phase plates by phase-volume holography on a photopolymer film. We implement such a component in a diode-pumped Nd:YAG oscillator to control the output spatial beam profile. Flattop super-Gaussian and square-shaped beams are obtained