A microwave photonic filter(MPF) with variable coefficient is proposed and demonstrated, which is constructed by a multi-wavelength fiber laser and Mach-Zehnder interferometer(MZI). Through changing the slope characte...A microwave photonic filter(MPF) with variable coefficient is proposed and demonstrated, which is constructed by a multi-wavelength fiber laser and Mach-Zehnder interferometer(MZI). Through changing the slope characteristics of Mach-Zehnder interference spectrum adjusted by optical variable delay line(OVDL), the conversion from phase modulation(PM) to intensity modulation(IM) is realized. The multi-wavelength fiber laser with Lyot-Sagnac optical filter has variable wavelength spacing. So the designed filter has a variable number of taps and tap weights. As a result, the tunable range of passband center frequency is 2.6 GHz. The reconfigurability of MPF can be also realized by adjusting the output of fiber laser.展开更多
为解决扰动监测系统定位精度低的问题,基于对光纤马赫-曾德尔干涉的研究,设计了改进型双马赫-曾德尔分布式光纤扰动监测系统。利用双马赫-曾德尔光纤传感系统光程差定位原理,通过互相关算法估算光程差导致的时间差确定扰动点。淹没于高...为解决扰动监测系统定位精度低的问题,基于对光纤马赫-曾德尔干涉的研究,设计了改进型双马赫-曾德尔分布式光纤扰动监测系统。利用双马赫-曾德尔光纤传感系统光程差定位原理,通过互相关算法估算光程差导致的时间差确定扰动点。淹没于高频噪声的扰动信号经自主设计的信号预处理电路,采用低通巴特沃斯滤波器滤除3.3 k Hz以上高频噪声,通过嵌入式采集与处理模块对得到的数据进行平滑滤波,提高了扰动信号的相关性,有效减小了定位误差。通过多次重复测试和数据分析结果表明,系统定位误差约为10 m,可用于扰动实时监测。展开更多
Recent developments in spectral white-light interferometry(WLI)are reviewed.Firstly,the techniques for obtaining optical spectrum are introduced.Secondly,some novel measurement techniques are reviewed,including the im...Recent developments in spectral white-light interferometry(WLI)are reviewed.Firstly,the techniques for obtaining optical spectrum are introduced.Secondly,some novel measurement techniques are reviewed,including the improved peak-to-peak WLI,improved wavelength-tracking WLI,Fourier transform WLI,and 3×3 coupler based WLI.Furthermore,a hybrid measurement for the intensity-type sensors,interferometric sensors,and fiber Bragg grating sensors is achieved.It is shown that these developments have assisted in the progress of WLI.展开更多
A multi-wavelength erbium-doped fiber laser （MEDFL） with simple line structure is experimentally demonstrated by using a Sagnac interferometer as a comb filter. It is shown that the multi-wavelength lasing is quite ...A multi-wavelength erbium-doped fiber laser （MEDFL） with simple line structure is experimentally demonstrated by using a Sagnac interferometer as a comb filter. It is shown that the multi-wavelength lasing is quite stable at room temperature due to the four-wave mixing （FWM） effect among different laser channels in the dispersion-shifted fiber cooperated in the laser cavity.展开更多
基金supported by the National High Technology Research and Development Program of China(No.2013AA014200)the National Natural Science Foundation of China(No.61107052)+1 种基金the Natural Science Foundation of Tianjin in China(No.14JCYBJC16500)the Science and Technology Development Fund Project of Tianjin University(No.2012)
文摘A microwave photonic filter(MPF) with variable coefficient is proposed and demonstrated, which is constructed by a multi-wavelength fiber laser and Mach-Zehnder interferometer(MZI). Through changing the slope characteristics of Mach-Zehnder interference spectrum adjusted by optical variable delay line(OVDL), the conversion from phase modulation(PM) to intensity modulation(IM) is realized. The multi-wavelength fiber laser with Lyot-Sagnac optical filter has variable wavelength spacing. So the designed filter has a variable number of taps and tap weights. As a result, the tunable range of passband center frequency is 2.6 GHz. The reconfigurability of MPF can be also realized by adjusting the output of fiber laser.
文摘为解决扰动监测系统定位精度低的问题,基于对光纤马赫-曾德尔干涉的研究,设计了改进型双马赫-曾德尔分布式光纤扰动监测系统。利用双马赫-曾德尔光纤传感系统光程差定位原理,通过互相关算法估算光程差导致的时间差确定扰动点。淹没于高频噪声的扰动信号经自主设计的信号预处理电路,采用低通巴特沃斯滤波器滤除3.3 k Hz以上高频噪声,通过嵌入式采集与处理模块对得到的数据进行平滑滤波,提高了扰动信号的相关性,有效减小了定位误差。通过多次重复测试和数据分析结果表明,系统定位误差约为10 m,可用于扰动实时监测。
基金This work was supported by the National Natural Scientific Foundation of China(51075037)the Program for New Century Excellent Talents(NCET)at the University of China and Chinese 863 Project(2008AA04Z406).
文摘Recent developments in spectral white-light interferometry(WLI)are reviewed.Firstly,the techniques for obtaining optical spectrum are introduced.Secondly,some novel measurement techniques are reviewed,including the improved peak-to-peak WLI,improved wavelength-tracking WLI,Fourier transform WLI,and 3×3 coupler based WLI.Furthermore,a hybrid measurement for the intensity-type sensors,interferometric sensors,and fiber Bragg grating sensors is achieved.It is shown that these developments have assisted in the progress of WLI.
基金the Science and Technology Department of Zhejiang Province(No.R104154 and 2004C31095)Science and Technology Bureau of Hangzhou Municipal Government(No.20051321B14).
文摘A multi-wavelength erbium-doped fiber laser （MEDFL） with simple line structure is experimentally demonstrated by using a Sagnac interferometer as a comb filter. It is shown that the multi-wavelength lasing is quite stable at room temperature due to the four-wave mixing （FWM） effect among different laser channels in the dispersion-shifted fiber cooperated in the laser cavity.
