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1.
为了实现太赫兹波的保偏波导传输,设计了一种含有纤芯缺陷孔和椭圆形包层空气孔的高双折射微结构光纤。通过在包层空气孔中选择性地填充太赫兹近零介电常量(epsilon-nearzero,ENZ)材料,引入了几何结构和材料分布的双重不对称性,破坏了2个偏振基模的简并以获得高双折射特性。应用有限元方法研究了光纤的双折射、损耗和色散等传输特性随结构参数的变化规律。在0.5 THz~2 THz的宽频段范围内获得了大于0.01的高双折射。x和y偏振基模的损耗在0.8 THz附近具有最小值,分别为0.903 dB·cm^(-1)和0.851 dB·cm^(-1)。纤芯缺陷孔可以有效调节色散特性,y偏振基模在1 THz~1.8 THz范围内具有(0±0.054)ps·THz^(-1)·cm^(-1)近零平坦色散特性。光纤的传输特性对ENZ材料的折射率变化不敏感。研究结论为研制太赫兹保偏光纤提供了理论参考。 相似文献
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以太赫兹低损耗聚合物材料Topas环烯烃共聚物为基材,设计了一种带隙型光子晶体光纤.光纤由三角形排列的圆角正六边形空气孔构成包层,缺失四个近邻空气孔构成近菱形的二重对称空气芯.采用有限元法分析了该光纤在太赫兹波段的传输特性.结果表明:在1.5THz附近约0.3THz的宽频范围内存在光子带隙,光纤可以基于光子带隙效应将太赫兹波束缚在空气芯中传输.在1.4~1.6THz范围内具有10-3数量级的高双折射;x偏振基模和y偏振基模的损耗都小于0.1cm-1,分别在1.53THz和1.5THz处达到最小值0.029 1cm-1和0.028 7cm-1.所设计的太赫兹Topas光子带隙光纤具备结构简单、易制备、直径小而易弯曲的特点. 相似文献
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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 相似文献
5.
为了在太赫兹波段实现远距离宽频带传输,设计了一种具有低吸收损耗的环烯烃共聚物(COC)作为基底材料双包层太赫兹光子晶体光纤。利用全矢量有限元法及模式选择理论,数值模拟了该光纤的单模传输范围、限制损耗、色散以及有效模场面积等特性。结果表明:优化结构参数可使在1~10 THz范围内基模限制损耗小于0.1 dB/m,二阶模限制损耗大于1 dB/m。因此可以获得1~10 THz的宽频带单模传输并且在1.5~10 THz内群速度色散可以控制在±0.1 ps/(THz·cm)。 相似文献
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设计了一种新型的六重准晶涡旋光光子晶体光纤,利用矢量有限元分析方法进行了数值模拟.研究结果表明光纤中模式有效折射率差?neff 10-4,实现了7个本征矢量模(10个相位涡旋光)的稳定传输,并以HE21为对象,对光纤模式的传输特性进行了分析研究.研究结果表明,在波段1500—1600 nm内,涡旋光模式的限制性损耗在10–8—10–7量级,模场面积保持在40μm2,非线性系数在10–3量级.通过改变光纤中心空气孔的大小,能够实现特定波段的色散平坦趋势,当中心空气孔为1.9μm时,光纤能够在1500—1800 nm波段保持色散平坦,色散系数维持在63.51—65.42 ps·nm–1·km–1之间. 相似文献
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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
11.
The variation of polarization mode dispersion (PMD) with V-parameter in single mode optical fibers due to core-ellipticity is studied by performing numerical simulations taking into account both geometrical and thermal-stress-induced birefringences as well as the variation of fiber refractive indices with wavelength. Simple empirical relations are given for calculating the mean PMD for any value of core-ellipticity and V-parameter of a standard single mode fiber. It is observed that the mean PMD saturates for V ? 1.8 leading to very small second order PMD. 相似文献
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Dispersion characteristic of MI and MII type single mode optical fibers is analytically investigated. For this purpose modal analysis of these fibers to obtain possible wave vectors for given system parameters are done. Then using numerical evaluation of the presented analytical relations, chromatic and waveguide dispersions are calculated. The effects of geometrical and optical parameters of the fibers on dispersion characteristics are investigated. In this analysis, we show that with increase of Δ (optical parameter) for MI structure the slope of dispersion curve is decreased and the case is reversed for MII structure. Also, with rising of Q (geometric parameter) for MI structure the slope of dispersion curve is decreased and the situation is reversed for MII structure. Finally, we show that with boosting of R2 for MII structure the slope of dispersion is increased. As a final result, our simulations show that small values for optical parameters are better in MII structure for multi-channel optical communications. In MI structure to obtain small dispersion slope, Q can be increased that is easy for fabrication in practice. Finally, Q and R2 are suitable parameters for control of dispersion in the proposed structures. 相似文献
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提出了一种新型双空气孔多芯-双模-大模场面积光纤结构, 计算了其模场分布、基模有效面积及弯曲损耗特性, 分析了各结构参量对其有效折射率及有效面积的影响. 这种结构在增大有效面积的同时使得二阶模的TE01, TM01模截止, 实现双模传输, 基模有效面积约为1044 μm2.调整其结构参量, 甚至可以达到单模传输.这种结构制作简单、设计灵活, 可用于高速大容量无源光纤及有源器件中.合理设计各结构参量, 可以使有效面积达到3512 μm2甚至更高, 从而满足光通信领域中大容量、高功率传输等实际应用的需求.
关键词:
多芯光纤
双模
大模场面积
弯曲损耗 相似文献
14.
We discuss the applicability of well-established classical optical fiber theories to holey fibers. By appropriately defining the V parameter, we can easily estimate the fundamental properties of holey fibers, such as effective index, group-velocity dispersion, mode field diameter, beam divergence, and splice loss, through simple empirical expressions without the need for heavy numerical computations. We confirm the validity of the V parameter defined here by comparing the calculated results with the earlier experimental and numerical results. 相似文献
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We experimentally investigated the limits to the endlessly single-modeness of large mode area photonic crystal fibers. We analyzed two versions of a commercial large mode area fiber with equal structural parameters but five or seven confining rings, and in both cases we found that the single mode regime becomes critical for short (<1 m) lengths. In these cases we report on the excitation of a second-order mode, whose microphotographed structure is very well reproduced by the results of numerical simulations. The multimodal behavior is further confirmed by polarization measurements. Also we found that the single-modeness is maintained in longer (>1 m) fibers. The same results were observed in large mode area fibers with different core sizes. 相似文献
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报道了利用800nm飞秒激光脉冲在多孔微结构光纤中产生超连续谱展宽的现象,连续谱展宽范围为440—890nm.基于标量波近似理论对微结构光纤包层的有效折射率和基模的有效面积以及光纤的色散特性进行了计算,发现微结构光纤具有特殊的控制色散和波导特性的能力,对超连续谱展宽的机理进行了初步解释.本文的理论分析和实验结果有较好的一致性,认为即使包层由无序填充气线组成的多孔微结构光纤也可以出现超连续谱展宽效应.
关键词:
多孔微结构光纤
超连续谱
有效折射率
色散 相似文献
17.
Modal cutoff in microstructured optical fibers 总被引:5,自引:0,他引:5
We analyze the nature of modal cutoff in microstructured optical fibers of finite cross section. In doing so, we reconcile the striking endlessly single-mode behavior with the fact that in such fibers all propagation constants are complex. We show that the second mode undergoes a strong change of behavior that is reflected in the losses, effective area, and multipolar structure. We establish the parameter subspace in which the fibers are single mode and an accurate value for the limit of the endlessly single-mode regime. 相似文献
18.
Sourabh Roy 《Optics Communications》2011,284(13):3280-3287
In this article, we describe a useful technique for calculating modes of practical optical waveguides having two-dimensional arbitrary transverse refractive index profile. The method uses a finite difference platform for evaluating Helmholtz's equation in scalar and semivectorial forms through a field evolution algorithm. The method is straightforward, easy to handle and does not involve any complex analysis or matrix formulation. We tested the accuracy of our analysis approach by applying it on a large number of realistic waveguide problems having known results or results available in the literature. The formulation has facilitated us to study the modal properties, viz., field distribution, birefringence, dispersion and mode effective area, of a variety of practical two-dimensional structures namely, planar structure, coupler, semiconductor optical waveguides, optical fibers and arbitrary profile microstructured fibers which are uniquely important in photonics and guided-wave devices. The algorithm will therefore be very useful in designing and studying any arbitrary-structure waveguides, and to explore new geometry and properties. 相似文献
19.
Nguyen Hoang Hai Yoshinori Namihira Shubi Kaijage Feroza Begum S. M. Abdur Razzak Kazua Miyagi 《Optical Review》2009,16(3):351-354
This paper proposes and demonstrates a novel type of silica index guiding holey fibers (IGHFs) that has two cladding layers
at the defective innermost structures. The proposed IGHFs exhibit remarkable chromatic dispersion properties such as nearly-zero
and flattened dispersion over a wide spectral range and single mode guidance along with very low confinement loss. The numerical
results indicate that 5 air-hole rings of nearly zero ultra-flattened dispersion single mode IGHFs can be designed with desire
flattened dispersion of over a 340 nm bandwidth including the entire band of interest with low confinement loss of less than
10−6 dB/m. 相似文献
20.
A. S. Abramov I. O. Zolotovskii D. I. Sementsov D. A. Stolyarov 《Optics and Spectroscopy》2014,117(5):792-798
Specific features of the formation of frequency-modulated pulses with large peak powers in amplifier-modulator-compressor cascade schemes based on length-inhomogeneous optic fibers are considered. Optimum profiles of fiber parameters ensuring the most effective amplification and modulation of pico- and subpicosecond frequency-modulated pulses are proposed. It is established that the use of a cascade consisting of active (gain) and passive (modulating) fibers with optimized profiles of the normal group-velocity dispersion and mode area can ensure the formation of pico- and subpicosecond pulses with energies higher than 100 nJ and peak powers above 100 kW. 相似文献