晶体包层型光纤偏振器的理论分析

本文对各向异性晶体包层型光纤偏振器进行理论分析.首先用外插法计算了五硼酸钾晶体在长波长范围的折射率,接着以平面介质波导模型计算一侧包层被晶体包裹的光纤偏振器的消光比,又以W光纤模型计算全部晶体包裹的光纤偏振器.最后将两种偏振器性能作了比较和讨论     

线圈型全光纤偏振器的研究

本文采用等效电流法对线圈型全光纤偏振器进行了分析计算.对应于保偏光纤中两正交传输基模的消光比,提出了一种分析保偏光纤弯曲损耗的新方法,这种方法基于将保偏光纤两个不同偏振模式分别等效为两个普通圆光纤的基模,等效参数通过测量不同偏振模式的模场半径来确定.实验证明这种理论计算方法与实验结果一致.最终,我们研制出的线圈型光纤偏振器在1.31μm工作波长下,实测消光比达30dB以上,工作偏振模式插入损耗≤3dB.     

光纤型偏振器消光比测试方法研究

介绍了单模光纤偏振器和保偏光纤偏振器 (包括研磨型保偏光纤偏振器和线圈型保偏光纤偏振器 )消光比的基本测试方法。单模光纤偏振器的基本测试方法有偏振控制器法和旋转波片法 ;研磨型保偏光纤偏振器的基本测试方法有起偏器 45°法和消偏法 ;线圈型保偏光纤偏振器的基本测试方法有偏振控制器法和消偏法。对每种方法的优点和缺点以及在测试过程中可能会出现的问题进行了详细分析 ,并通过实验进行了验证     

干涉式光纤陀螺光路偏振特性的理论分析

首次采用琼斯矩阵建立了消偏型干涉式光纤陀螺完整光路传输系统的数学模型。在此基础上进行了光路偏振特性的理论分析,讨论了各器件的性能对陀螺偏振噪声的影响,分析了光纤消偏器的消偏作用。通过分析计算,得到了消偏型干涉式光纤陀螺的最大偏振误差表达式。在不同精度级别的消偏型光纤陀螺中,计算出了光纤消偏器应该达到的精度要求,为今后减小零漂打下了理论基础。     

旋转光纤圆起偏器的特性分析

基于旋转光纤耦合模理论,对窄带和宽带旋转光纤圆起偏器的特性进行了计算分析.研究了注入光的偏振态、光纤固有线双折射和旋转速率对窄带圆起偏器最小工作长度的影响,并借助多包层光纤的分析方法,分析了旋转光纤各参量变化对宽带圆起偏器工作带宽的影响.结果表明:窄带圆起偏器的最小工作长度与光纤固有线双折射和光纤旋转速率有关,而与注入光的偏振态无关|改变光纤旋转速率可调节宽带圆起偏器的工作带宽,改变应力区到纤芯的距离可改变宽带圆起偏器的中心波长.     

双偏振结构保偏光纤偏振器的研制

提出了保偏光纤偏振器的一种串联结构,即双偏振结构,报道了研制的结果。并通过对单偏振结构和双偏振结构器件测试结果的比较,得出双偏振结构的保偏光纤偏振器可使器件达到高消光比,并且有稳定的温度特性。     

在线单模光纤偏振控制器研究

利用Ｐｏｉｎｃａｒｅ球理论首次全面分析了在线全光纤偏振控制器。结果发现该偏振器可以有八种不同路径，实现任意偏振态之间的转化，最后通过实验验证了其工作性能。     

旋转光纤圆起偏器的特性分析

基于旋转光纤耦合模理论,对窄带和宽带旋转光纤圆起偏器的特性进行了计算分析.研究了注入光的偏振态、光纤固有线双折射和旋转速率对窄带圆起偏器最小工作长度的影响,并借助多包层光纤的分析方法,分析了旋转光纤各参量变化对宽带圆起偏器工作带宽的影响.结果表明:窄带圆起偏器的最小工作长度与光纤固有线双折射和光纤旋转速率有关,而与注入...     

金属覆层保偏光纤偏振器的五层波导模型及理论分析

对金属履层保偏光纤偏振器建立了五层波导变参量物理模型,设计了自适应套孔爬山法的数值计算方法求解含多层波导本征值的复超越方程,计算结果揭示了金属覆层偏光纤偏振器的物理机制,并对器件进行了优化设计,给出了实验结果。     

单模光纤中线偏振皮秒脉冲光的光致多脉冲现象的新解释

结合单模光纤的本征线性双折射与非线性双折射效应，利用二偏振分量的耦合方程对单模光纤中线偏振皮秒脉冲光的光致多脉冲现象作出了解释，得到的计算结果与实验符合得很好。     

10-GHz Optical Comb in L-Band Region With Brillouin/Erbium-Doped Fibre Laser

A multiwavelength Brillouin/erbium fibre laser (BEFL) which operates in the long wavelength (L-band) region is demonstrated for potential applications in an L-band wavelength division multiplexing (WDM) communication system. The laser configuration consists of a long erbium-doped fibre to enable L-band amplification where two 3-dB couplers take a portion of the generated BEFL signal and re-inject it into the single mode fibre to seed a cascaded BEFL line in the same direction as the first BEFL line. A stable and strong laser comb of up to five lines with 10-GHz spacing has been obtained with a Brillouin pump (BP) of 9.2 mW and a 980 nm pump of 92 mW. The BEFL has shown a broad tuning range with a tuning characteristic for line #1 which is flat over a range greater than 9.9 nm.     

Erbium-doped twin-core fibre narrow-band filter for fibre lasers

Theoretical analysis of a recently experimentally demonstrated erbium-doped twin-core (ErTCF) fibre saturable-absorber-based narrow-band tracking filter is presented. Basic qualitative characteristics of the filter are deduced from an analogy with an ideally inhomogeneously broadened saturable absorber while the effect of wide band saturation of absorption due to spatial overlap of individual spectral components of the radiation is studied in detail using a numerical model based on coupled mode theory, resolved in space and frequency. The effect of the input power, twin-core fibre length and laser operating wavelength on the spectral characteristics of the filter is investigated.     

应用于红外跟踪系统的光纤耦合技术

本文介绍了一种解决红外跟踪系统中探测器和致冷器组件位于万向支架机构上各种弊病的方法。利用纤维光束的柔软性，应用光纤耦合技术，可以让探测器和致冷器组件放在离万向支架一定距离上。文中着重论述了光纤与探测器间的光耦合问题，并就一组合透镜耦合方案作了具体设计计算。最后谈了谈光纤耦合技术研究的总体思路和对以后工作的设想。     

Numerical modelling and experimental investigation of double-cladding erbium–ytterbium-doped fibre amplifiers

A comprehensive model for characterising double-cladding erbium–ytterbium-doped fibre amplifiers (EYDFAs) is proposed and experimentally verified for the first time to our knowledge. The model is based on rate and propagation equations in a homogeneous two-level active medium and takes into account the modified pump absorption arising from the double-cladding structure and the presence of ytterbium ions. The influence of the cladding pumping scheme on the multimode pump absorption, radial population inversion and the amplified spontaneous emission are also modelled. The numerical mode is capable to predict amplifier gain, output spectra, gain saturation and amplifier noise. The model has been fully validated in a large number of operating conditions and a fairly good agreement is obtained between the experimental data and the numerical simulations over a wide range of input parameters.     

Optical microfiber passive components

Optical microfiber waveguides with diameters close to the wavelength of light possess an intriguing combination of properties, such a tight modal confinement, tailorable dispersion, and high nonlinearity, which have been utilized in many passive applications. Here, the key fabrication techniques and optical properties of microfibers are introduced, followed by a discussion of the various passive microfiber devices and sensors. Applications exploiting their strong confinement are reviewed, including harmonic generation, supercontinuum sources, gratings, tips for optical trapping and intracellular sensing and subwavelength light sources, as well as devices based on large evanescent fields such as couplers, interferometers, optical manipulators, sensors, and resonators. Furthermore, the properties and practical intricacies of manufacturing various microfiber resonators are evaluated, with a focus on their applications in sensing ranging from temperature monitoring to current, pressure, refractive index and chemicals detection.     

Polymer optical fibre Bragg gratings based fibre laser

For the first time the fibre laser constructed from a polymer optical fibre Bragg grating is reported. The single frequency laser with the peak power of −5 dBm and signal to noise ratio greater than 45 dB has been achieved. Further examination demonstrates the excellent characteristics of the fibre laser. First, the fibre laser can be easily tuned over 35 nm by the simple axial tension method. Second, the fibre laser has the high strain sensitivity of 1.48 pm/με with the dynamic measurement range as large as 2.37%.     

Multi-wavelength generation of L-band brillouin/erbium fibre laser

In this paper, the operation of the Brillouin/erbium fibre laser (BEFL) in the long wavelength band (L-band or 1565–1625 nm) is experimentally demonstrated. The Stokes frequency is shifted 10 GHz from its Brillouin pump (BP) from 1598 to 1612 nm for the single wavelength BEFL. Multiple wavelength generation in the BEFL is realised by adding two 3-dB couplers, which are joined in a reverse-S arrangement to take a portion of the generated BEFL signal and re-inject it into the single-mode fibre (SMF) to seed a cascaded BEFL line in the same direction as the first BEFL line. Twenty lines including the anti-Stokes are obtained with a maximum BP and 980-nm pump power of 8.8 and 92 mW, respectively. The L-band BEFL has the potential to be used in future wavelength division multiplexing (WDM) communication system.     

Theoretical analysis on double Rayleigh backscattering noise in optical fibreRaman amplifiers and its suppression

In this paper, amplified double Rayleigh backscattering noise (DRB) in the optical fibre Raman amplifier is analysed. Expressions are presented for both forward pumping and backward pumping schemes. Calculation is performed to show the effective suppression of DRB noise by employing an optical isolator. The optimal position for the isolator is determined and is found to be insensitive to the power levels of the signals and pumps. The results show that a reduction of the DRB noise by almost 2 to 3 orders can be reached.     

单模光纤布拉格反射滤波器

采用非对称五层光波导模型，分析了光纤布拉格反射滤波器特性，讨论实现窄带和宽带高反射滤波器的结构参数。文中报道关于光纤布拉格反射滤波器的实验研究，包括制作工艺和测试方法。典型的光纤布拉格反射滤波器在１．５μｍ波段的反射率达８０％，带宽１．５ｎｍ。     

Comprehensive research on self phase modulation based optical delay systems

This paper comprehensively investigates the properties of self phase modulation based optical delay systems consisting of dispersion compensation fibre and highly nonlinear fibres.It researches into the impacts of power level launched into highly nonlinear fibres,conversion wavelength,dispersion slope,modulation format and optical filter bandwidth on the overall performance of optical delay systems.The results reveal that,if the power launched into highly nonlinear fibres is fixed,the time delay generally varies linearly with the conversion wavelength,but jumps intermittently at some conversion wavelengths.However,the time delay varies semi-periodically with the power launched into highly nonlinear fibres.The dispersion slope of highly nonlinear fibres has significant influence on the time delay,especially for the negative dispersion slope.The time delay differs with modulation formats due to the different combined interaction of nonlinearity and dispersion in fibres.The bandwidth of the optical filters also greatly affects the time delay because it determines the bandwidth of the passed signal in the self phase modulation based time delay systems.The output signal quality of the overall time delay systems depends on the conversion wavelength and input power level.The optimisation of the power level and conversion wavelength to provide the best output signal quality is made at the end of this paper.