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1.
Yang Yue Guiyun Kai Zhi Wang Yan Li Chunshu Zhang Yunfei Lu Tingting Sun Long Jin Jianguo Liu Yange Liu Shuzhong Yuan Xiaoyi Dong 《Optics Communications》2006,268(1):46-50
In this paper, we propose a novel photonic crystal fibre (PCF) with high phase birefringence and very low group birefringence. It is composed of a solid silica core and a cladding with helix-pattern air holes. Using a full-vector finite-element method, we study the phase and group modal birefringence of such PCF at various air-hole sizes, pitches and wavelengths. Owing to this innovative structure of air holes, a high phase to group modal birefringence rate is obtained. Its phase modal birefringence is as large as 10−4 magnitude; however, the group modal birefringence of this PCF is at 10−7-10−6. The phase birefringence is 2 orders of magnitude larger than group birefringence over a broad wavelength span, which means that the light with different polarization and effective index has almost a same group velocity. As a result, the group modal birefringence that closely relates to the polarization modal dispersion is negligible. 相似文献
2.
高双折射光子晶体光纤研究 总被引:6,自引:2,他引:4
设计了一种高双折射光子晶体光纤(Photonic Crystal Fiber,PCF),即增大两个与纤芯相邻的空气孔直径,使光纤只具有二重对称性,呈现出较高的双折射.通过压缩x轴方向孔间距,进一步增大双折射度.采用全矢量有限单元法(Finite-element Method,FEM),研究了该光子晶体光纤基模对应的相双折射和群双折射,给出了该高双折射PCF双折射随输入光波长的变化曲线.结果获得了10-3量级的高双折射.具有设计参量的该光子晶体光纤结构的相双折射在1 550 nm处可以达到5.0×10-3,在更长的波长处,这一值会更高. 相似文献
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本文提出了一种对普通三角晶格多孔光纤隔行分层填充匹配材料, 实现超高模式双折射的方法. 首先, 采用全矢量有限元法对多孔度为43.08%的三角晶格多孔光纤的传输特性进行了详细研究. 随后, 为增强结构非对称性对纤芯空气孔隔行填充折射率为1.4的液体, 发现光纤的模式双折射显著提高, 在峰值处(1.1 THz)由填充前的1.05×10-3增大到1.36×10-2; x, y两偏振模式基模的吸收损耗系数分别由0.16 dB/cm增大到0.25 dB/cm和0.28 dB/cm; 光纤的工作带宽由1.1 THz增大到1.9 THz. 研究发现通过增大填充材料的折射率能够显著提高光纤的模式双折射; 当n=2, f=2.2 THz时, 光纤能够达到8.03×10-2的超高模式双折射. 进一步, 采用隔行分层填充的方式, 在不同层填充不同折射率的液体, 实现折射率的梯度分布, 从而增强光纤对导模的限制能力. 结果显示, 采用该填充方法, 光纤的模式双折射在工作频段内没有峰值, 呈现单调递增的趋势. 当f=2.2 THz时, 模式双折射达到7.19×10-2. 该设计不仅实现了超高的模式双折射, 同时还具备可调谐的特性, 对实际应用具有重要意义. 相似文献
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A modified hexagonal index guiding photonic crystal fiber made of pure silica with high birefringence and a low effective modal area is proposed, and properties, including birefringence and effective modal area, are numerically analyzed using the multipole method. Numerical results show that high birefringence of 1.362 × 10−2 and a low effective modal area of 3.435 μm2 are achieved at 1.55 μm, simultaneously. Moreover, impacts of hole spacing and hole size on birefringence and effective modal area are also investigated in detail. 相似文献
6.
B.M.A. Rahman A.K.M.S. Kabir M. Rajarajan K.T.V. Grattan V. Rakocevic 《Applied physics. B, Lasers and optics》2006,84(1-2):75-82
Modal solutions of photonic crystal fibers with equal and unequal circular air holes in a hexagonal matrix are presented,
by using a rigorous full-vectorial finite element-based approach. The effective indices, mode field profiles, spot-sizes,
modal hybridness, modal birefringence and group velocity dispersion values have been determined and presented. The effects
of the pitch-distance, hole diameter, structural asymmetry, air hole arrangement and the operating wavelength on the modal
birefringence are also reported. It is shown that a significant value of birefringence can be achieved by using only circular
air holes, which would be easy to fabricate, and by operating it close to its modal cutoff.
PACS 42.81.Qb; 42.81.Gs; 42.25.Bs; 31.15.Pf 相似文献
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Based on a full-vector model, a theoretical study on a kind of high birefringence photonic crystal fibre is presented. Due to introducing air holes of two different sizes into the cladding, twofold rotational symmetry was obtained. We demonstrate the possibility of achieving high birefringence that is at least one order of magnitude higher than that of conventional polarization-maintaining fibres. The dependences of modal birefringence, modal field and differential group delay on the structure parameter of the fibres are discussed in detail. The numerical results are in very good agreement with the experimental results in the literature. 相似文献
9.
Rafal Kotynski Maciej Antkowiak Francis Berghmans Hugo Thienpont Krassimir Panajotov 《Optical and Quantum Electronics》2005,37(1-3):253-264
In this paper we are modeling the interplay of material and form birefringence in photonic crystal fibers. We introduce an efficient numerical method for the calculation of the modal structure. Our approach relies solving the fully vectorial wave equation for the transverse magnetic field and the respective propagation constants using a plane wave expansion. The method accounts for a simple form of material anisotropy. Our analysis is relevant to certain application areas, and in particular to fiber sensing, where material birefringence arises for instance due to transversally applied mechanical stress. We analyze the influence of material birefringence on the modal birefringence and the state of polarization of the fundamental mode. 相似文献
10.
基于超格子构造法,采用全矢量模型研究了具有中心缺陷孔的椭圆光子晶体光纤的传输特性。着重讨论了中心缺陷孔对光纤中基模的模场分布、双折射特性和色散特性的影响。研究表明:与椭圆孔光子晶体光纤相比。由于中心椭圆缺陷孔的引入,使该光纤具有更高的模式双折射。光纤的传输特性对光纤的结构参量和波长具有较强的依赖关系。随着波长和中心缺陷孔的增加。双折射将增大,其模式双折射在10^-3量级。改变光纤的结构参量,可以获得超宽带的色散平坦或异常的色散特性。分析结果显示,当中心孔的尺寸de/D=0.4时。在波长1.55μm附近,可获得近400nm的色散平坦区。 相似文献
11.
矩形点阵微结构聚合物光纤偏振特性研究 总被引:3,自引:0,他引:3
采用全矢量平面波方法,以聚合物为基材,研究了矩形点阵微结构聚合物光纤的传输模场和偏振性质.结果发现,矩形点阵微结构聚合物光纤基模两个正交偏振态不再简并,模场呈现类矩形且具有较强的线偏振特性;该光纤模式双折射产生于包层孔结构分布的不对称性,减小包层纵向孔间隔和横向孔间隔之比η值,双折射明显增强,适当调节η,可在更宽频带范围内实现高双折射单模运行. 相似文献
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偏振保持光纤是单模光纤的一种特殊类型,其模式双折射与温度、芯和皮折射率差及椭圆度、热膨胀系数、光纤直径、弹性模量、泊松比、频率、波长、拉丝张力等诸多因素有关,对与偏振保持光纤模式双折射相关的上述因素进行分析,指出光纤模式双折射越高,光纤的偏振态保持就越好,为更好地设计新型保偏光纤或合理选择保偏光纤类型奠定了基础. 相似文献
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A novel hole-assistant microstructured optical fiber with a rectangle-like core and four elliptical holes as cladding is proposed. By employing a full-vector finite element method, the modal birefringence and confinement loss are numerically investigated, and the results show that in such a structure, an ultrahigh modal birefringence of 2.91×10−2 and a low confinement loss (<1 dB/km) can be simultaneously obtained at excited wavelength of 1.55 μm. It is significant that such a microstructured optical fiber is easily fabricated with its simple structure and exhibits improved performance. 相似文献
15.
A novel highly flat elliptical-hole holey fiber with a squeezed lattice is introduced for achieving extremely high birefringence. The fiber consists of two kinds of elliptical holes with the same major axis length and different minor axis lengths for the core and cladding regions. Numerical results demonstrate a modal birefringence exceeding 0.065. 相似文献
16.
Using the finite element method, this paper investigates lateral
stress-induced propagation characteristics in a photonic crystal
fibre of hexagonal symmetry. The results of simulation show the
strong stress dependence of effective index of the fundamental
guided mode, phase modal birefringence and confinement loss. It also
finds that the contribution of the geometrical effect that is
related only to deformation of the photonic crystal fibre and the
stress-related contribution to phase modal birefringence and
confinement loss are entirely different. Furthermore,
polarization-dependent stress sensitivity of confinement loss is
proposed in this paper. 相似文献
17.
Eliminating the birefringence in silicon-on-insulator ridge waveguides by use of cladding stress 总被引:2,自引:0,他引:2
Xu DX Cheben P Dalacu D Delâge A Janz S Lamontagne B Picard MJ Ye WN 《Optics letters》2004,29(20):2384-2386
We propose and demonstrate the use of the cladding stress-induced photoelastic effect to eliminate modal birefringence in silicon-on-insulator (SOI) ridge waveguides. Birefringence-free operation was achieved for waveguides with otherwise large birefringence by use of properly chosen thickness and stress of the upper cladding layer. With the stress levels typically found in cladding materials such as SiO2, the birefringence modification range can be as large as 10(-3). In arrayed waveguide grating demultiplexers that were fabricated in a SOI platform, we demonstrated the reduction of the birefringence from 1.2 x 10(-3) (without the upper cladding) to 4.5 x 10(-5) when a 0.8-microm oxide upper cladding with a stress of -320 MPa (compressive) was used. Because the index changes induced by the stress are orders of magnitude smaller than the waveguide core-cladding index contrast, the associated mode mismatch loss is negligible. 相似文献
18.
通过在纤芯附近引入两个直径较大的空气孔诱导纤芯局部双折射,在包层减小x方向的孔间隔诱导包层双折射,设计实现了一种高双折射随波长可调效应的微结构光纤.采用全矢量平面波方法,以聚合物甲基丙烯酸甲酯为基材,对其偏振特性和基模模场进行了研究.结果发现,该光纤基模双折射在光通信波段呈现两个最大值,且最大双折射大小和位置随光纤结构和波长的变化可以进行调节.通过调节光纤结构参数,模拟得到了该光纤具有高双折射和零偏振模色散的最佳设计参数.
关键词:
导波与光纤光学
双折射可调
聚合物
全矢量平面波法 相似文献
19.
Improved high birefringence photonic crystal fibres with dispersion flattened and single mode operation
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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. 相似文献
20.
Three different types of photonic crystal fibers have been investigated which promise very large birefringence. The first type fiber is band gap guiding, the second index guiding, while the third type is index guiding with high refractive index circular and elliptical regions in the innermost ring. The birefringence, group velocity dispersion, modal effective index and mode field area of these fibers have been numerically estimated by employing finite difference time domain method. When elliptical regions are introduced in the first and second rings with the combination of small circular regions, each of these proposed fibers exhibits large birefringence with shifted zero dispersion point. Among these three different types of fibers, the band gap guiding photonic crystal fiber promises the largest birefringence (~5.45×10?2) reported so far. The value of the birefringence and group velocity dispersion of these fibers can be controlled by controlling the hole pitch. Largest birefringence is achieved with a specific value of hole pitch. 相似文献