南强讲座490期 我院主办

讲座时间：2012年4月28日周六 下午3：00

讲座地点：海韵园教学楼104

讲座教授：鲍晓毅教授

鲍晓毅教授是加拿大渥太华大学物理系教授，2002年当选加拿大光纤光学与光电子学首席科学家（终身），2009年当选为加拿大科学院数理部院士，目前是国际光学工程师学会(SPIE)院士和美国光学学会(OSA)院士，国际上光纤布里渊散射分布式传感器的领军人物。

鲍晓毅于1987年获中国科学院安徽光学精密机械研究所光学专业博士学位后，赴国外深造，分别在美国堪萨斯州立大学、德国马普量子光学研究所与雷根斯堡大学、英国斯特拉斯克莱德大学、英国肯特郡大学工作和学习过。现任加拿大渥太华大学物理系教授。取得的国际公认学术成就主要：基于布里渊损耗机制的分布式光纤传感器，同时测量应变和温度的高空间分辨率检测技术，保障结构安全的分布式布里渊传感器，利用布里渊散射使光变慢的方法及光通信系统性能劣化的补偿技术。

讲座题目：Optical Fiber Sensors based on Brillouin scattering（基于布里渊散射的光纤传感系统）

讲座摘要：Brillouin scattering in optical fiber describes the interaction of an electro-magnetic field (photon) with a characteristic density variation of the fiber. When the electric field amplitude of an optical beam (so-called pump wave), and another wave is introduced at the downshifted Brillouin frequency (namely Stokes wave), the beating between the pump and Stokes waves creates a modified density change via the electrostriction effect, resulting in so-called the stimulated Brillouin scattering. The density variation is associated with a mechanical acoustic wave; and it may be affected by local temperature, strain, and vibration which induce changes in the fiber effective refractive index and sound velocity. Through the measurement of the static or dynamic changes in Brillouin frequency along the fiber one can realize a distributed fiber sensor for local temperature, strain and vibration over tens or hundreds of kilometres. This paper reviews the progress on improving sensing performance parameters like spatial resolution, sensing length limitation and simultaneous temperature and strain measurement. These kinds of sensors can be used in civil structural monitoring of pipelines, bridges, dams, electrical power generator, an railroads for disaster prevention. Analogous to the static Bragg grating, one can write a moving Brillouin grating in fibers, with the lifetime of the acoustic wave. The length of the Brillouin grating can be controlled by the writing pulses at any position in fibers. Such gratings can be used to measure changes in birefringence, which is an important parameter in fiber communications. Applications for this kind of sensor can be found in aerospace, material processing and fine structures.

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