一种新型高双折射光子晶体光纤

提出了一种新的高双折射光子晶体光纤结构.应用全矢量频域有限差分方法所做的数值分析表明：该结构光纤基模的两个正交偏振态不再简并，其模式呈现很强的线偏振特性,并且模式双折射与结构参数设置有密切关系.通过选择合适的结构参数，可以使之达到10^-2量级，比传统的D型和熊猫型保偏光纤高出2个数量级.合理设计光纤包层的几何结构，可以取得理想的色散效果.这种结构的光子晶体光纤可用于制作具有适当色散特性或偏振特性的保偏光纤及相关光纤器件. 关键词： 光子晶体光纤 模式双折射 偏振特性 频域有限差分法     

PBG光子晶体光纤的色散特性研究

光子晶体光纤(PCF)是一种具有特殊包层结构的光纤,它是利用光子禁带效应(PBG)来导光的。利用时域有限差分法(FDTD)来分析光波在PCF中传输的色散特性,结果表明,PBG光子晶体光纤的色散值和色散斜率比常规的通信光纤要小。     

菱形纤芯光子晶体光纤色散与双折射特性分析

针对光子晶体光纤多零色散点、高双折射的应用要求, 设计了一种新型结构的光子晶体光纤, 其纤芯由位于菱形四个角上的圆形空气孔组成. 通过有限元数值分析方法对该种结构光子晶体光纤的色散特性和双折射特性进行数值仿真, 得到色散与波长、色散与纤芯圆孔尺寸、双折射与波长、双折射与纤芯圆孔尺寸的关系. 研究结果表明:在满足光纤传输功率要求的条件下, 光纤的双折射在d₁<0.8 μupm 时的性能较好. 同时, 该种结构的光子晶体光纤在芯区直径满足d₁=0.4 μupm或 d     

菱形纤芯光子晶体光纤色散与双折射特性分析

针对光子晶体光纤多零色散点、高双折射的应用要求, 设计了一种新型结构的光子晶体光纤, 其纤芯由位于菱形四个角上的圆形空气孔组成. 通过有限元数值分析方法对该种结构光子晶体光纤的色散特性和双折射特性进行数值仿真, 得到色散与波长、色散与纤芯圆孔尺寸、双折射与波长、双折射与纤芯圆孔尺寸的关系. 研究结果表明:在满足光纤传输功率要求的条件下, 光纤的双折射在d₁<0.8 μupm 时的性能较好. 同时, 该种结构的光子晶体光纤在芯区直径满足d₁=0.4 μupm或 d₁=0.6 μupm时会出现两个零色散点, 这对进一步研制具有多零色散点的光子晶体光纤具有重要的意义.     

八边形结构的双折射光子晶体光纤

提出一种新型的双折射光子晶体光纤,在正八边形的基础上改变纤芯附近的几个空气孔的直径产生双折射.利用多极法对该光纤基模的模场分布、色散、限制损耗及双折射特性进行数值分析,并且分析了一些参数对双折射的影响.计算了具有相同参数的六边形结构光子晶体光纤的色散系数、限制损耗及双折射率.研究表明,具有相同参数的八边形结构光子晶体光纤比六边形结构光子晶体光纤的双折射率明显提高,限制损耗大幅度减小,零色散波长也向短波方向移动. 关键词： 光子晶体光纤 双折射 色散 限制损耗     

基于图像处理的频域有限差分法用于实际光子晶体光纤的研究

提出了一种基于图像处理算法和频域有限差分法相结合研究实际光子晶体光纤的数值分析方法.该方法针对实际光子晶体光纤由于结构不规则难以进行数值分析的缺点.采取首先对光子品体光纤的电镜扫描图像使用阈值分割和维纳滤波等图像处理算法获得光纤截面的几何网像.然后使用图像插值及构造均值移动窗口滤波等方法实现了网格划分和介电系数平均等步骤,最后结合频域有限差分法对光纤特性进行分析计算.结果表明,该方法能够精确分析实际光子晶体光纤的色散特性.模拟得到的实际光子晶体光纤的模场分布与实验结果吻合很好.     

高双折射纳米结构光子晶体光纤特性研究

设计了一种高双折射高非线性纳米结构光子晶体光纤,利用电磁场散射的多极理论研究了这种光纤的双折射、基模模场、色散以及非线性特性.数值研究发现,加大纤芯及包层空气孔的非对称程度,可使双折射变大,其双折射最大值可达1.918×10-2.通过调节孔节距大小,可将双折射最大值调至所需波长处,孔节距为400nm的纳米光子晶体光纤在800nm波长处非线性系数高达0.2m-1.W-1,同时在750—1000nm的波段有较大的双折射值,高双折射和高非线性在纳米结构光子晶体光纤中实现了完美的结合.对新型纳米光子器件的研制和集成光学的发展具有重要意义.     

一种高双折射高非线性多零色散波长光子晶体光纤

设计了一种高双折射高非线性多零色散波长的全内反射光子晶体光纤,采用有限元法研究了这种光纤的有效模面积、非线性、色散和双折射特性.计算结果表明,通过设置合适的结构参数,该光纤可在波长1.55μm处获得2.54×10-2的双折射,也可在X,Y偏振方向分别获得50.22 W-1·km-1和54.61 W-1·km-1的高非线性系数.另外,该光纤在近红外波段出现了两个零色散波长,其中的一个零色散波长出现在1.55μm附近.本设计为获得高双折射高非线性多零色散波长的光子晶体光纤提供了一种新的结构,其在偏振控制、非线性光学、色散管理和超连续谱传输方面具有广泛的应用前景.     

新型高双折射光子晶体光纤特性分析

将单模光子晶体光纤的空气孔设计成椭圆形增加其结构的不对称性,可以破坏模式中两偏振态的简并,达到实现双折射特性的目的.据此,提出了一种新型的高双折射光子晶体光纤.该模型通过在纤芯引入两个小空气孔以及将包层的第一环和中间一行变为椭圆空气孔来造成光纤模式的不对称性,获得了高双折射特性.之后对该结构的色散特性及模场面积等特性进行了数值模拟,并且讨论了外包层空气孔的几何参数改变对于该模型色散特性的影响.采用全矢量平面波展开法,并且以完美匹配层作为边界条件对该结构光子晶体光纤的上述特性进行分析.结果表明,该结构光子晶体光纤可以在较宽的波长范围内产生10-3量级的模式双折射,并且从1 100～1 800nm范围内具有平坦色散特性,同时具有小模场面积特性.为基于超平坦色散、高双折射和高非线性光子晶体光纤的光纤器件的制作和应用提供理论基础.     

高非线性光子晶体光纤色散特性的研究

采用矢量光束传输法对不同结构参量的高非线性光子晶体光纤的非线性特性和色散特性进行了数值分析,计算得出高非线性光子晶体光纤的物理参量基模有效面积Aeff 、非线性系数γ和色散系数D.分析了Aeff 、γ和D与高非线性光子晶体光纤结构参量空气孔间距Λ、空气孔直径d之间的关系.分析结果表明,通过调节光子晶体光纤的结构参量可以灵活地调整高非线性光子晶体光纤的非线性特性和色散特性.     

Analysis of high birefringence photonic crystal fiber with octagonal and squarely lattice

Aiming at the requirement of high birefringence, a new kind of photonic crystal fiber (PCF) with octagonal and squarely lattice is proposed. In this structure, squarely lattices are added in the inner layer to obtain high birefringence. Birefringence and dispersion as a function of wavelength and size of PCF are analyzed by using Finite Element Method (FEM). Simulation results show that this kind of PCF exhibits high birefringence with a magnitude of 10^?3, and one zero dispersion point is obtained simultaneously. In addition, the characteristics of PCF can be tuned by changing the size of fiber.     

复合四边形空气孔格点光子晶体光纤的色散特性分析

提出了一种复合四边形空气孔格点光子晶体光纤,其包层是由两种不同大小的空气孔组合而构成的.利用时域有限差分法(FDTD)对其色散特性进行了分析.结果表明,通过调节包层中两种不同尺寸的空气孔的大小以及孔间距这三个参量,可以得到不同水平的平坦色散曲线,甚至超平坦的色散曲线.     

Improved high birefringence photonic crystal fibres with dispersion flattened and single mode operation

A kind of improved high birefringence photonic crystal fibre (PCF) is proposed in this paper. The characteristics of birefringence, dispersion and leakage loss are studied by the multipole method. Numerical results show that the improved PCF possesses the properties of a flat dispersion and single mode operation. Moreover, with the operating wavelength λ = 1.55μm, the modal birefringence increases greatly in comparison with that of the original PCF, and the leakage loss is about 10⁴ times smaller than that of the original PCF because the modification gives rise to the strong confinement of guided modes. It is expected that the improved PCF can be used as high birefringence and dispersion flattened fibres.     

Novel single-mode and polarization maintaining photonic crystal fiber

In this paper, we present and propose a novel structure for improved birefringence and single-mode propagation condition photonic crystal fiber (PCF) in a broad range of wavelength. The birefringence of the fundamental mode and single mode property in such a PCF is numerically estimated by employing full vector finite element method (FVFEM) and anisotropic perfectly matched layers (APML). The simulation results illustrate that we can achieve a high birefringence and perfect single-mode condition by employing silica-filled into one-line elliptical air holes parallel to x-axis and rotated by an angle. Obviously, the proposed PCF is quite useful for optical devices.     

用于液体传感的高双折射新型光子晶体光纤结构

提出一种用于液体传感的光子晶体光纤的结构和设计方法。将六边形光子晶体光纤的纤芯区域设计成2个椭圆空气孔，分别填充水和乙醇，进而比较两种光子晶体光纤结构的传播特性。采用全矢量有限元法对所设计光子晶体光纤结构的双折射、相对灵敏度、限制损耗、非线性系数进行数值分析，对光纤各项参数的优化及纤芯椭圆结构参数进行调整，结果表明:当椭圆率为0.6时，纤芯填充乙醇的光子晶体光纤PCF2在波长1.55 nm处相对敏感度可达到72.506 7%，同时限制损耗可以降至10?8级。所设计的模型可用于传感和生物传感研究及应用。     

Mid-infrared high birefringence bow-tie-type Ge20Sb15Se65 based PCF with large nonlinearity by using hexagonal elliptical air hole

A high birefringence Ge₂₀Sb₁₅Se₆₅ based photonic crystal fiber (PCF) is proposed. It consists of a central defect core surrounded by two kinds of elliptical air holes with different size. The Finite Difference Time Domain method (FDTD) is used to simulate the guided modes of the designed PCF. The properties of this PCF are investigated including the birefringence, nonlinearity, and polarization mode dispersion in the mid-infrared range. The results show that for the optimized structure parameters, the highest birefringence of 0.1176 is obtained. The maximum nonlinearity coefficients of 38390 w^?1km^?1 and 49760 w^?1km^?1 for x- and y-polarization modes are achieved.     

Modeling photonic crystal fiber for efficient soliton pulse propagation at 850 nm

We numerically investigate the dynamics of soliton propagation at 850 nm in chloroform filled liquid core photonic crystal fiber (LCPCF) by using both finite element method (FEM) and split step Fourier method (SSFM). We propose a novel chloroform filled PCF structure that operates as a single mode at 850 nm featuring an enhanced dispersion and nonlinearity for efficient soliton propagation with low input pulse energy and low loss over small distances. We adopt the projection operator method (POM) to derive the pulse parameter equations which clearly describes the impact of fourth order dispersion on the pulse propagation in the proposed PCF. To analyse the quality of the pulse, we perform the stability analysis of pulse propagation numerically and compare our results of the newly designed chloroform filled PCF with that of standard silica PCF. From the stability analysis, we infer that the soliton pulse propagation in modified chloroform filled PCF is highly stable against the perturbation.     

Design of highly birefringent chalcogenide glass PCF: A simplest design

In this article, a new simplified structure of a highly birefringent chalcogenide As₂Se₃ glass photonic crystal fiber (PCF) is designed and analyzed by using fully vectorial finite element method. The effective indices, confinement loss, birefringence, and chromatic dispersion of fundamental polarized mode are calculated in the proposed PCF for a wide wavelength range. To maintain the polarization in chalcogenide As₂Se₃ glass PCF, we enlarged two of the central air holes and reduced two transverse air holes for achieving high birefringence. This helps in creating an effective index difference between the two orthogonal polarization modes. It is also shown that As₂Se₃ glass PCF provides lower chromatic dispersion and less confinement loss compared to silica PCF of the same structure in wavelength range 1.3 to 1.8 μm and hence such chalcogenide As₂Se₃ glass PCF have high potential to be used in dispersion compensating and birefringence application in optical communication systems. In addition to this, the polarization mode dispersion (PMD) result of the proposed PCF is also reported.