磁光光纤光栅滤波器的全光时钟提取性能研究

研究了磁光耦合强度对磁光光纤布喇格光栅中模式转换光反射光谱特性的影响.根据磁光耦合模理论并结合光纤布喇格光栅的传播特性,数值分析了磁光光纤布喇格光栅的磁控特性,得到了3dB带宽可调的滤波器.采用级联磁光光纤布喇格光栅构造磁控梳状滤波器,实现了40Gbps归零数据信号的全光时钟提取仿真,分析了时钟信号的抖动性能与磁光耦合参量的关系.     

用拉伸和二次曝光法制作基于莫阿光纤光栅的带通滤波器

我们利用一块均匀掩膜版,通过对光纤拉伸和二次紫外曝光的方法制作了一基于莫阿-布喇格光纤光栅的带通滤波器,其带通宽度为0.28nm.我们对这种方法制作的莫阿-布喇格光栅作了理论分析.在此文中,还给出了均匀光纤光栅的拉伸特性.     

使用FBG及更短光纤的高效Er3+-Yb3+共掺双包层光纤放大器

提出在光纤放大器中,使用光纤布喇格光栅作为泵浦光反射镜,所需的双包层光纤可以缩短,同时至少保持了与没有光纤布喇格光栅作为反射镜时光纤放大器相同的性能.基于速率及传输方程,对使用和不使用光纤布喇格光栅的铒、镱共掺双包层光纤放大器的性能进行了数值模拟.结果表明,使用光纤布喇格光栅作为反射镜时光纤放大器可以获得与无光栅时相同的输出功率,但仅仅需要后者长度一半的光纤,无论是前向泵浦还是后向泵浦.对后向泵浦方式并使用光纤布喇格光栅作为反射镜,可获得最高的输出功率及光增益,同时使用了较短的光纤.     

带有布喇格光栅的光纤失配耦合器的传输特性分析

本文利用模式耦合理论,分析了光纤失配耦合器在耦合区带有一个布喇格光栅后两光纤中基模场的传输特性,得到基模场发生耦合现象的条件及满足的方程。采用数值分析方法模拟耦合现象,并得出了带有布喇格光栅的光纤耦合器用于波分复用/解复用的最优化设计方案。     

基于保偏光纤取样光栅的宽频带滤波方法

提出一种新型刻录在保偏光纤上的取样布喇格光纤光栅.利用耦合模方程分析了此种光纤光栅的光谱特性,并利用切趾函数对光栅的输出谱进行了优化处理,最终可以实现高品质的宽频带多波长滤波.频带宽度为普通取样布喇格光纤光栅的2倍,经过切趾处理后,此种光纤光栅的边模抑制比也有显著提高.     

带有布喇格光栅的光纤失配耦合器的传输特性分析(英文 )

本文利用模式耦合理论,分析了光纤失配耦合器在耦合区带有一个布喇格光栅后两光纤中基模场的传输特性,得到基模场发生耦合现象的条件及满足的方程． 采用数值分析方法模拟耦合现象,并得出了带有布喇格光栅的光纤耦合器用于波分复用／解复用的最优化设计方案．     

基于洛伦兹函数微扰的磁光光纤布喇格光栅线性透射谱和非线性双稳特性研究

基于非线性耦合模理论,利用逆向递推龙格-库塔法,数值研究了在磁光耦合系数中引入洛伦兹函数微扰后对磁光光纤布喇格光栅线性透射谱和非线性双稳特性的影响.研究结果表明:给磁光耦合系数引入洛伦兹微扰能在线性透射谱阻带中打开线宽极窄的一个透射窗口,微扰宽度和微扰中心位置可以影响透射窗口的位置、宽度以及峰值大小;当微扰宽度和微扰中心位置发生变化时,光栅的双稳特性表现出明显的差异,合理地选择微扰参量可以实现对其双稳特性的优化.     

聚合物太赫兹光纤布喇格光栅

研究了一种基于聚合物太赫兹光纤的太赫兹光纤布喇格光栅.通过二氧化碳激光器或紫外激光器点对点加工聚合物太赫兹光纤,实现聚合物太赫兹光纤直径的周期性调制,从而实现太赫兹光纤布喇格光栅的周期性折射率调制.基于有限元方法和光纤布喇格光栅相关理论,考虑反射峰波长、反射率、带宽、光纤长度、光纤直径和光纤直径形状变化程度等因素,研究了太赫兹光纤布喇格光栅的特性.理论模拟表明,反射峰波长和光栅周期存在与传统光学波段光纤布喇格光栅不同的非线性关系.     

基于掺铒光纤/喇曼混合放大的光纤激光器布喇格光栅传感系统

提出了一种提高长距离光纤布喇格光栅信噪比以进行准分布测量的新方法.该方法基于掺铒光纤/喇曼混合放大的光纤激光器结构,掺铒光纤和滤波器构成的环形结构产生激光作为光源,喇曼光纤放大器对布喇格光栅信号进行低噪音的双向放大,置于远处的掺铒光纤利用剩余的泵浦功率产生自发辐射光和放大传感信号,为远处掺铒光纤之后的布喇格光栅传感器提供信号光以及补偿由于长距离传输造成的光纤损耗.实验显示,与使用宽带光源的传感方式相比,系统的性能得到显著提高,仅使用小功率泵浦,分布在50 km光纤上的FBG均获得了超过58 dB的优良信噪比.     

基于洛伦兹函数微扰的磁光光纤布喇格光栅线性透射谱和非线性双稳特性研究

基于非线性耦合模理论,利用逆向递推龙格-库塔法,数值研究了在磁光耦合系数中引入洛伦兹函数微扰后对磁光光纤布喇格光栅线性透射谱和非线性双稳特性的影响.研究结果表明:给磁光耦合系数引入洛伦兹微扰能在线性透射谱阻带中打开线宽极窄的一个透射窗口,微扰宽度和微扰中心位置可以影响透射窗口的位置、宽度以及峰值大小;当微扰宽度和微扰中...     

Characteristics of light polarization in magneto-optic fiber Bragg gratings with linear birefringence

The coupling between guided optical waves in magneto-optic fiber Bragg gratings(MFBGs) with linear birefringence is investigated using the eigen-mode and coupled-mode approaches.The relationship between the polarization-dependent loss(PDL) and the eigen states of polarization(SOPs) in the MFBGs is discussed.Only the MFBGs with low linear birefringence are applied to the peak PDL-based magnetic field measurement,after which the linear dynamic range is determined using the relative magnitude of linear and mag...     

Longitudinal coupling effect in microfiber Bragg gratings

We theoretically present longitudinal coupling effect (LCE) in air-cladding microfiber Bragg gratings (MFBGs). Distinct from conventional weakly-guiding optical fibers, large longitudinal electric field (E_z) exists in wavelength-scale microfibers. Due to LCE, MFBG reflectivity can be reduced by more than 30% within the band-gap and the full width at half maximum (FWHM) is obviously narrowed. This theoretical analytical work is instructive to precisely design and fabricate MFBGs that are promising in the areas of optical sensing and nanophotonics.     

磁光光纤Bragg光栅中圆偏振光的非线性传输特性

提出了磁光光纤Bragg光栅的理论模型,给出了圆偏振光在磁光光纤光栅中传播的非线性耦合模方程. 研究表明,在磁光光纤Bragg光栅中,光栅引起正反传播方向的导波光发生耦合,法拉第效应引起磁圆双折射效应,而非线性效应则将左旋和右旋圆偏振光耦合在一起,它们的共同作用可使双稳态状态发生反转、非线性光控光开关阈值功率降低. 与传统光纤光栅相比,利用左旋和右旋磁圆偏振光之间的交叉相位调制实现的脉冲整形具有磁光偏置可调特性,为基于磁光光纤光栅的动态灵活全光3R再生器的研制提供了理论基础. 关键词： 磁光光纤Bragg光栅 圆偏振光 脉冲整形     

Diffraction of light from a stripe domain structure with tilted domain walls

The intensity and polarization parameters of light waves diffracted from a stripe domain structure with tilted domain walls and the magnetic moment in domains oriented parallel to the walls are determined in the approximation of thin layers and linear magnetooptical coupling.     

Magneto-Optic Fiber Gratings Useful for Dynamic Dispersion Management and Tunable Comb Filtering

Intelligent control of dispersion management and tunable comb filtering in optical network appfications can be performed by using magneto-optic fiber Bragg gratings （MFBGs）. When a nonuniform magnetic field is applied to the MFBG with a constant grating period, the resulting grating response is equivalent to that of a conventional chirped grating. Under a linearly nonuniform magnetic field along the grating, a linear dispersion is achieved in the grating bandgap and the maximal dispersion slope can come to 1260ps/nm2 for a l0-mm-long fiber grating at 1550nm window. Similarly, a Gaussian-apodizing sarnpled MFBG is also useful for magnetically tunable comb filtering, with potential application to clock recovery from return-to-zero optical signals and optical carrier tracking.     

The possibility of measuring linear and quadratic magnetooptical effects in magnetic field under conditions of magnetomechanical resonance

We have considered the possibility of measuring the linear and quadratic (in magnetic field) magnetooptical effects in magnetooptical crystals that are simultaneously exposed to a constant (polarizing) magnetic field and to an alternating magnetic field under conditions of magnetomechanical resonance. The use of a Mueller polarimeter in combination with spectral analysis of the intensity of the light wave at the output of the polarimeter makes it possible to selectively determine elements of the Mueller matrix and minimize the amount of measurements. We have shown that there is a possibility of solving the inverse problem on finding two components of the alternating magnetic field in which a magnetooptical crystal is placed.     

基于长周期光纤光栅的磁场传感方案的实现

长周期光纤光栅是近几年出现的一种新型光纤器件。其耦合机理是前向传输的纤芯基模与前向传输的各阶包层模式之间的耦合 ,这与光纤布喇格光栅明显不同。它对温度、应力、弯曲及外部折射率的变化具有相当高的灵敏度 ,是一种理想的光纤型敏感结构。提出利用长周期光纤光栅谐振波长的移动或移动变化量进行磁场强度的测量 ,并进行了理论推导、仿真实验及分析研究。得出了谐振波长变化量与外界磁场强度的关系模型。分析了设计中应该考虑的因素。     

Coupling between spin and orbital degrees of freedom in KCuF3

We present the results of resonant x-ray scattering experiments on KCuF3. Structurally forbidden reflections, corresponding to magnetic and 3d-orbital long-range order, have been observed. Integrated intensities have been measured as a function of incident energy, polarization, azimuthal angle, and temperature. The results give evidence for a strong coupling between orbital and spin degrees of freedom. The interplay between magnetic and orbital order parameters is revealed by the temperature dependence of the intensity of orbital Bragg peaks.     

记录结构对体光栅各向异性衍射选择特性研究

以静态体光栅各向异性衍射理论分析模型为基础，将与体光栅厚度有关的记录光强调制度引入到各向异性耦合波方程中.利用耦合波理论分析了光折变晶体中体光栅的各向异性衍射性能，研究了在不同初始记录光强比的条件下，记录光入射角的改变对光折变体光栅各向异性布喇格衍射性能的影响.结果表明：记录光入射角和记录光初始光强比均对体光栅的各向异性衍射具有选择性；与此相比，记录光入射角和记录光初始光强比对于体光栅各向同性衍射不具备选择性.