共查询到20条相似文献,搜索用时 109 毫秒
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论述了单模光纤受到弯曲时应力双折射效应的产生。同时探讨了利用这种双折射效应制作多种在线型光纤器件,包括波片,滤波器,声波传感器等。 相似文献
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传感光纤中的残余线性双折射、温度和振动敏感性严重影响着Sagnac 式全光纤电流传感器的精度。设计了一种可用于全光纤电流传感器的扭转高双折射光纤,该光纤由两端变速率扭转部分和中间匀速率扭转部分组成。其中,变速扭转部分能实现线偏振光和圆偏振光之间的相互转化,具有/4 波片功能;匀速扭转部分,具有较小的光纤固有线性双折射和圆保偏功能,从而可更为精确地感应法拉第效应。将这种扭转高双折射光纤绕制成特殊结构传感光纤环, 解决了Sagnac 效应以及电流导体位置对全光纤电流传感器测量结果的影响。理论上建立了扭转高双折射光纤的耦合模方程,模拟了线偏振光入射该光纤时光波偏振状态演化情况。在此基础上设计一种新型的抗振型Sagnac 式电流传感器。 相似文献
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提出了一种光纤光栅传感解调新方法。系统由1个3dB耦合器、1个传感光纤布喇格光栅、1个双折射光纤环镜和1个探测器构成,高双折射光纤环镜作为边缘滤波器。光纤光栅波长的线性解调带宽为3.6nm。对双折射光纤环镜的温度补偿进行了实验研究,实验表明,封装的高双折射光纤环镜能够补偿高双折射光纤环镜的温度漂移。补偿前的高双折射光纤环镜波长随温度漂移为2.3nm/℃,补偿后的双折射光纤环镜波长随温度漂移为0.005nm/℃,远小于未补偿的双折射光纤环镜波长随温度漂移。 相似文献
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本文研究了多包层单模光纤的双折射特性,分析了光纤椭圆偏心率及剖面形状对双折射和群时延差的影响。计算结果表明,改变光纤偏心率或选择适当的工作频率及剖面形状可获得低双折射或高双折射的保偏单模光纤。 相似文献
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一种Sagnac干涉仪结构的光子晶体光纤温度传感器 总被引:4,自引:0,他引:4
采用Sagnac干涉仪结构,设计了一种高双折射光子晶体光纤环镜温度传感器。光子晶体光纤温度稳定性好,通过向高双折射光子晶体光纤空气孔填充热光系数高的液体材料乙醇,从而实现温度传感的目的。采用平面波展开法,分析了高双折射光子晶体光纤的双折射与传输波长和温度的关系。理论分析表明,填充乙醇后,高双折射光子晶体光纤的双折射随着传输波长和温度的增加而增加,且双折射与温度成线性关系。实验中将一段填充乙醇的高双折射光子晶体光纤与3 dB耦合器熔接制作成Sagnac干涉仪结构的光纤环镜,当温度从 45 ℃升至80 ℃时,光谱仪上观察到凹点λi向短波方向漂移了309.280 nm,温度灵敏度高达8.837 nm/℃。 相似文献
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光纤1/4波片是光纤电流传感系统中的关键器件,为此提出并实现了一种1/4波片制作方法。该方法将两段长度近似相等的高双折射光纤(HBF)以轴间夹角90°进行熔接,然后拉伸其中一段光纤使得它们的相位差为π/2,从而制成1/4波片。调节时,将正交熔接的光纤接入到3dB耦合器构成高双折射光纤环镜(Hi-Bi FLP),实时检测环镜的透过率以确定相位差。推导了检测系统的透过率公式,详细分析了调节过程中透过率曲线的变化规律,并根据透过率及透过率曲线的斜率来确定相位差。搭建了调节系统,验证了该方法的可行性。该方法具有准确度高、调节方便等优点。 相似文献
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《Microwave Theory and Techniques》1980,28(7):722-725
Previous analyses of periodically coupled multimoded systems have assumed equal spacing of the coupling points. In this paper, explicit simple formulas are developed to account for randomized variations of a periodically coupled system. This analysis is useful in multimoded transmission systems utilizing circular waveguides or fiber optics and in active systems such as traveling wave tubes and surface acoustic wave devices. 相似文献
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Ming-Yue Fu Wen-Fung Liu Tzu-Chiang Chen Hao-Jan Sheng 《Photonics Technology Letters, IEEE》2003,15(10):1392-1394
The coupling phenomenon between the cladding mode and the core mode in a blazed-superstructure fiber grating is experimentally demonstrated in this letter by applying both transverse and longitudinal acoustic waves. This is based on the difference between the cladding-mode wave vector and the core-mode wave vector, which is equivalent to the acoustic wave vector. By this means, a reflectivity-tunable multiwavelength switchable comb filter would be developed for the applications in fiber optics. 相似文献
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本文根据矩阵光学理论和ABCD定律,导出了高斯光束经锥形发散梯度折射率纤维透镜变换的束腰共轭成像公式在。|l_o—l_f|>>Z_0的球面波近似条件下,本文结果化为几何光学成像公式。 相似文献
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海水盐度光学检测技术研究进展 总被引:2,自引:0,他引:2
在一定温度条件下,海水的盐度与其折射率之间存在线性对应的关系,因此通过测量海水折射率可以推算出其盐度.详细介绍了几种利用光学方法测量液体折射率,从而间接检测海水盐度的技术,主要包括光纤光栅传感检测法、表面等离子波检测技术和利用几何光路折变计算折射率的检测技术,重点分析了各种方案的传感器结构、工作原理、影响测量精确度的因素,以及在实际应用中存在的问题,最后对光学技术在海水盐度实时检测中的可行性进行了展望. 相似文献
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A slight deviation from the resonant condition virtually stops the exchange of energy between two parallel fibers. When one fiber is birefringent, and the other isotropic and lossy, the energy of only one polarization mode swaps back and forth between two fibers and is eventually absorbed. The scalar wave equation is used to investigate the resonant effect. It is found that energy conservation is an intrinsic property of the solution of the scalar wave equation for any trial function, and that standard coupled mode equations obtained from Maxwell's equations can be derived from the scalar wave equation in an exact way. The resonant effect discussed can provide very high extinction ratio at extremely low penalty of additional loss. For example, an extinction ratio of 1.2×104 dB with a penalty of 0.2 dB can be expected after 1-km transmission for waveguide parameters common in fiber optics 相似文献
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An analysis is presented for calculating the backscattered fields of an electromagnetic plane wave by lossless dielectric spheres of arbitrary density. This method involves the Watson transformation which serves to split the exact Mie solution, given as an infinite series, into the geometrical optics fields and the diffracted fields. The former comes from the illuminated region of the sphere and may be obtained from the geometrical optics method. The latter comes from the shadow region and consists of two different types of surface waves. One is a "creeping wave" analogous to that of perfectly conducting spheres. The other is a wave which enters the sphere and emerges as a surface wave in the shadow region. This wave is unique to dielectric spheres and is the stronger of the two surface waves. In the widely used geometric optics methods it is assumed that the optics fields are the dominant contributors even though stationary rays which are not in the direction of backscatter must be added in to give a degree of agreement with the exact Mie series results. In this paper we derive the optics fields and show that they differ in some respects from those obtained by the geometric optics method. They are smaller than heretofore assumed and contribute negligibly to the backscatter in this particular range ofka (4-20). Using our rigorous approach we can show the diffracted fields to be the major contributors to the total backscatter. Numerical results for the backscattering cross sections using diffracted and optics fields, and optics fields alone will be presented for relative index of refraction of 1.6. The agreement between our results (diffracted and optics) and exact results from the Mie series is excellent. A subsequent paper will be concerned with the diffracted fields. 相似文献
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Technological improvements in free space optical communication systems have reduced the cost and alternatives to fiber optic transmission. The advantages of the free space optical link over fiber optic cabling are primarily economic. In line with the demand for gigabyte link from 10 Mbit/s to 10 Gbit/s in the market, the uses of free space optical communication systems have increased exponentially from 1995 to 2008. However, free space optics is subject to atmospheric effects such as attenuation and scintillation which can reduce link availability and may introduce errors not seen in fiber transmission. In this paper we argue that optical wireless communication is an alternative to fiber optic transmission in short and medium range wireless communications and we discuss that the liability and availability of the free space optical link is mainly determined by the local atmospheric condition, this is to say that the transmission quality may be affected by weather conditions. For the evaluation we constructed an experimental communication network with a free space system. One way to characterize the strength of the turbulence fluctuation is by examining the Rytov variance for a plane wave. This Rytov variance physically represents the intensity fluctuation induced by atmospheric turbulence. 相似文献