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1.
Electrically tunable dispersion compensator with fixed center wavelength using fiber Bragg grating 总被引:1,自引:0,他引:1
Ngo N.Q. Li S.Y. Zheng R.T. Tjin S.C. Shum P. 《Lightwave Technology, Journal of》2003,21(6):1568-1575
We present the design and development of a novel tunable dispersion compensator with fixed center wavelength that is based on the electrical adjustment of the chirp of a fiber Bragg grating (FBG). Both temperature gradient and strain gradient are employed to adjust the chirp of the FBG jointly. The electrical current flowing through the taper on-fiber thin-film heater will introduce a temperature gradient on the FBG. The shrinkage of a negative thermal expansion coefficient (NTEC) ceramic due to the temperature rise will compress the tapered FBG mounted inside it, and this will introduce a strain gradient on the FBG. The center wavelength of the FBG will be kept fixed because the effect of temperature rise on the FBG and the effect of compression of the FBG will offset each other. Applying an electrical power of less than 0.68 W, we demonstrate a linearly chirped FBG whose dispersion can be continuously adjusted from -178 ps/nm to -302 ps/nm with a central wavelength shift of as small as 0.16 nm. 相似文献
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Bo Dong Shiya He Shuyang Hu Dawei Tian Junfeng Lv Qida Zhao 《Photonics Technology Letters, IEEE》2006,18(24):2620-2622
A novel time-division-multiplexing fiber Bragg grating (FBG) sensor with a tunable pulsed laser is proposed and demonstrated. A tunable pulsed fiber laser based on a matched FBG is applied. The wavelengths of the sensing FBGs are obtained by detecting maximum voltages with a photodiode, which avoids a complex demodulation process. The advantages of the sensor include simple structure, high signal-to-noise ratio, and the sensing signals obtained by detecting the maximum voltages 相似文献
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室温稳定多波长光纤激光器技术的研究新进展 总被引:2,自引:1,他引:2
室温稳定的多波长光纤激光器( MWFL)中最关键的技术是如何有效抑制掺杂光纤的均匀展宽效应。综述了国际上近年来提出的实现室温稳定多波长光纤激射的主要技术。介绍了近几年我们在该领域的一些创新性研究工作:提出了多种基于多谐振峰的光纤布拉格光栅(FBG) ,如多模光纤布拉格光栅、保偏光纤布拉格光栅、取样光纤布拉格光栅等的可开关多波长光纤激光器的新方法和新结构,实现了多种波长间隔小于2 nm,室温工作稳定性好、波长及波长间隔可调的可开关多波长光纤激光器;提出了基于非线性光纤环镜( NOLM)和非线性偏振旋转(NPR)效应的两种多波长掺铒光纤激光器(EDFL)实现技术,实现了室温稳定、功率谱分布平坦的宽带多波长激光输出,3 dB带宽内的波长个数可达50个,每个波长的功率波动在2 h内小于0 .1 dB。 相似文献
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为了进一步提高光纤光栅解调系统的性能,提出和研究了一种新颖的基于可调谐F-P(Fabry-Perot)滤波器的光纤光栅解调技术,并以此为基础构建了探测系统。系统使用一个固定波长的参考光纤光栅作为波长参考元件,通过对传感光纤光栅与参考光纤光栅的波长测量与差值运算,消除了可调谐FP滤波器腔长漂移对测量精度的影响。给出压电陶瓷电压对应的伸长量,有效地减小了压电陶瓷非线性对测量的影响,提高了光纤光栅波长的测量精度。在测量范围内,最大非线性偏差为0.5%。 相似文献
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Metallic and other type of coatings on fiber Bragg grating (FBG) sensors alter their sensitivity with thermal and mechanical stress while protecting the fragile optical fiber in harsh sensing surroundings. The behavior of the coated materials is unique in their response to thermal and mechanical stress depending on the thickness and the mode of coating. The thermal stress during the coating affects the temperature sensitivity of FBG sensors. We have explored the thermal response of FBGs coated with Al and Pb to an average thickness of 80 nm using flash evaporation technique where the FBG sensor is mounted in a region at room temperature in an evacuated chamber having a pressure of 10?6 Torr which will minimize any thermal stress during the coating process. The coating thickness is chosen in the nanometer region with the aim to study thermal behavior of nanocoatings and their effect on FBG sensitivity. The sensitivity of FBGs is evaluated from the wavelengths recorded using an optical sensing interrogator sm 130 (Micron Optics) from room temperature to 300 °C both during heating and cooling. It is observed that the sensitivity of the metal coated fibers is better than the reference FBG with no coating for the entire range of temperature. For a coating thickness of 80 nm, Al coated FBG is more sensitive than the one coated with Pb up to 170 °C and it reverses at higher temperatures. This point is identified as a reversible phase transition in Pb monolayers as the 2-dimensional aspects of the metal layers are dominant in the nanocoatings of Pb. On cooling, the phase transition reverses and the FBGs return to the original state and for repeated cycles of heating and cooling the same pattern is observed. Thus the FBG functions as a sensor of the phase transitions of the coatings also. 相似文献
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Buric M. Tong Chen Maklad M. Swinehart P.R. Chen K.P. 《Photonics Technology Letters, IEEE》2009,21(21):1594-1596
A palladium-coated fiber Bragg grating (FBG) inscribed in high attenuation fiber (HAF) capable of measuring hydrogen concentration at -150 degC, well below the 4% explosion limit, is presented. The low-temperature performance of the sensor was improved by heating the gratings as much as 300 K above the ambient temperature with highly attenuated infrared laser light. The sensitivity and response time of the FBG hydrogen sensor were studied as functions of fiber temperature. Through the selection of length and the loss per meter of the HAF, the self-heating scheme demonstrated here enables numerous FBG hydrogen sensors to be multiplexed in a single fiber for multipoint hydrogen sensing using a single fiber feedthrough. 相似文献
7.
聚合物封装光纤布拉格光栅传感器温度压力特性研究 总被引:9,自引:2,他引:7
分析了聚合物封装光纤布拉格光栅(FBG)传感器温度与压力响应特性。通过实验对某种特殊聚合物封装光纤光栅的温度与压力响应进行研究,发现当温度变化范围较大时.由于温度对材料弹性模量的影响.光纤光栅的压力响应灵敏度不再为常数,而是随温度变化的。当温度在30℃时.其压力响应灵敏度为0.036nm/MPa.在180℃时则变为0.175nm/MPa,且灵敏度系数随温度的变化呈分段线性变化。因此在使用聚合物封装实现光纤光栅传感器增敏以及大范围温度和压力的同时测量时,需要将弹性模量作为温度的函数.代入光纤光栅温度与压力响应灵敏度系数矩阵公式中以消除大范围温度变化对聚合物力学特性的影响。 相似文献
8.
Union self-compensated packaging of FBG strain sensor 总被引:1,自引:0,他引:1
To solve the cross-sensitivity to temperature of fiber Bragg grating(FBG)strain sensor,an effective method is firstly proposed for the discrimination of strain and temperature by using a single FBG adopting a special compensated structure,which is based on the thermal stress.The relationship of strain and temperature responses of FBG is analyzed theoretically.The experimental results are in agreement with the obtained theoretical analyses.This sensor structure has excellent characteristics,such as simple structure,easy manufacture and higher strain sensitivity. 相似文献
9.
《Photonics Technology Letters, IEEE》2006,18(19):2038-2040
Four$pi$ -phase shifts are introduced in a uniform fiber Bragg grating (FBG) structure to realize a quadruple-transmission-band filter with ultranarrow 40-pm wavelength spacing. Four separate single-wavelength lasings at 1552.60, 1552.63, 1552.67, and 1552.71 nm, and three pairs of dual-wavelength lasings among above four wavelengths, are achieved stably by incorporating the quadruple-transmission-band FBG filter in a fiber ring cavity with a tunable uniform FBG acting as coarse frequency selection. This new kind of laser will be very useful in applications requiring closely spaced and tunable single- or dual-wavelength components. 相似文献
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In this paper, we propose and experimentally demonstrate a series of new all-fiber, tunable, and highly selective filters based on fiber gratings and Fabry-Perot's. The structures combine high fiber Fabry-Perot (FFP) selectivity and fiber Bragg grating (FBG) bandpass nature and presents high flexibility in the response by using nonuniform gratings. An ultraselective filter (a few MHz in range) is also addressed by cascading two FFP 相似文献
13.
Recently, a tunable fiber Bragg grating (FBG) was developed by using stress-responsive colloidal crystals. In this paper, we have simulated the application of these nanoparticles into the super-structured fiber Bragg grating (SSFBG) written with perfect sequences derived from a short maximal-length sequence. A tunable SSFBG will be available to overcome the prohibitive temperature variation of the optical codecs. Nevertheless, we presented a method to implement coherent time spreading optical code-division multiple-access (OCDMA) where a unique code (or perfect sequence) can be reused and mixed with different wavelengths to obtain a tunable wavelength-division multiplexing (WDM) system. In order to maximize the binary throughput, we have selected a unique short maximal-length sequence composed of 7 chips that can be tuned with 7 different optical wavelengths. We found thousands of different tunable combinations that presented power contrast ratios (P/C) higher than 12 dB. When a WDM-OCDMA system used 2 different combinations simultaneously, the perfect binary detection with error correction codes was achieved successfully. The tunable SSFBG with colloidal crystals will be a simple and good alternative choice for fiber-to-the-home (FTTH) communications. 相似文献
14.
Metal coating of fiber Bragg grating and the temperature sensing character after metallization 总被引:2,自引:0,他引:2
In this study, the fiber Bragg grating (FBG) was metallized with a nickel coat using an electroless-electro plating method. Under the optimum conditions, the surface of chemical plating and electroplating coat are smooth and compact, there is not any visible defect in the cross-section. The effects of the nickel coat on the properties of the fiber sensor were studied. With this plating method, the FBG can be well protected and its sensing properties can be changed. When the temperature is changed, a thermal stress between the metal coat and the fiber will be induced because of the thermal expansion coefficients difference. The thermal stress influence on the temperature sensing properties of the metalized FBG was analyzed, and a physical-mathematical model for FBG temperature sensing was presented. Experimental results show the mathematical model is feasible to explain the mechanism of temperature sensitivity enhancement for metalized FBG. 相似文献
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为满足光纤光栅传感技术在高真空热环境下的应用,分析了丙烯酸酯和聚酰亚胺2种不同涂覆层单模紧套光纤作为传输光纤,在高真空热环境下对FBG峰值功率的影响,并进行了实验验证。首先,设计了高真空热环境下传输光纤等效模型;接着,设计了不同涂覆层光纤传输损耗特性影响实验方案,搭建了硬件在环检测平台;最后,进行了实验验证,探索了在高真空热环境条件下,不同涂覆层单模传输光纤随着温度、真空度变化对FBG反射谱功率峰值影响规律。实验结果表明:真空度从常压降至10-4 Pa水平再恢复至常压,丙烯酸酯和聚酰亚胺2种不同涂覆层单模传输光纤温度从常温降至-196℃再恢复至常温,历经224 h,FBG反射谱功率峰值均不发生变化,为光纤传感技术在高真空(压力约为10-4 Pa水平)、热环境(-196~25℃循环)中应用提供理论及实验依据。 相似文献
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进行了液氦温度(4.2 K)到室温(298 K)温区内光纤Bragg光栅(FBG)温度传感性能的实验研究.重点分析了液氦温度(4.2 K)到液氮温度(77 K)FBG的温度传感特性.实验表明:FBG传感特性与温度相关.在50 K以下,温度响应基本没有变化;50 K-77 K,波长偏移量随温度上升变化不规律;150 K-298 K传感特性近似成线性.对比裸光栅与涂敷光栅,涂敷光栅的温度灵敏度远大于裸光栅的温度灵敏度.选用外加热膨胀系数大的聚合物封装,可以显著提高FBG的温敏系数和线性度. 相似文献
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Measured results from a microwave photonic traversal filter exploiting fiber Bragg grating (FBG) arrays and achieving a high-performance tunable bandpass microwave response are presented. Tuning is affected by changing the optical carrier wavelength to select the operating gratings, and the high-quality frequency response is obtained by weighting the reflections of the gratings. This experiment demonstrates that sophisticated passive signal processing functionality can be achieved practically using FBGs 相似文献
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《Optical Fiber Technology》2013,19(2):121-125
A new method for fine control of the group delay of a fiber Bragg grating (FBG) is presented. It is based on an acoustic wave applied to the fiber. The standing acoustic wave imposes a periodic chirp to the uniform FBG. Tunability is obtained through adjustment of the intensity and/or frequency of the acoustic wave. A fast switching time of ∼17 μs was achieved. The experimental results were verified by theoretical simulation showing a good agreement between them. It can be used for different applications such as tunable narrow dispersion compensator for independent coarse wavelength division multiplexing (CWDM) channels or optical delay lines. 相似文献