共查询到20条相似文献,搜索用时 31 毫秒
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We propose and demonstrate a novel type of bending-insensitive single-mode hole-assisted fiber that has a doped core and two layers of holes with two different airhole diameters. The fiber has a 9.3 microm mode field diameter, a bending loss of 0.011 dB/turn at 1.55 microm for a bending diameter of 10 mm, and a cutoff wavelength below 1.1 microm. The fiber can be fusion spliced to a conventional single-mode fiber with low loss. 相似文献
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We experimentally investigate the spectral characteristics of side-polished endlessly single-mode photonic crystal fibers of different polishing depths and radii of curvature that are important to mode field diameter, evanescent coupling, waveguide losses, higher-order mode excitation, and dispersion slopes of photonic crystal fiber components. A polished photonic crystal fiber with a greater polishing depth or a larger radius of curvature shows a more dispersive characteristic. In contrast to conventional single-mode fibers, in photonic crystal fibers the evanescent field is more strongly localized, and the propagating light can be more efficiently guided within the deformed core. 相似文献
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提出并设计了一种基于电光聚合物的锥形波导,可用于单模光纤与电光聚合物波导器件之间的连接.锥形波导中采用了宽度锥形和折射率锥形结构.宽度锥形采用劈形形状,通过宽度和折射率的缓慢变化实现模场转换.劈形形状的宽度锥形具有较小的损耗且易于制作,折射率锥形可采用灰度掩膜光刻技术制作.研究了锥形波导的传输损耗与锥形波导的长度、波导宽度和厚度、材料吸收损耗等参数的关系及其优化,分析了锥形波导中的功率传输、模场分布与模式转换效率.结果显示锥形波导的传输损耗小于0.37 dB,光纤-波导-光纤的连接损耗优于1.62 dB,对插入损耗的改善达到8.78 dB,模场转换效率达到了83.7%. 相似文献
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We propose the use of subwavelength structures in a waveguide grating to achieve polarization-independent coupling of light between an optical fiber and a silicon-on-insulator (SOI) optical waveguide. The subwavelength structure allows the mode effective indices of the TE and TM modes in the grating section to be precisely engineered. We calculate that coupling efficiency of over 64% is possible using the proposed design for polarization-independent coupling between single-mode optical fibers and SOI nanophotonic waveguides. 相似文献
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We present a new design for beam splitting components employing a silicon-on-insulator rib waveguide structures. In the new design, a high-index thin-film layer is deposited in the rib section to reduce the wave field dispersive tails in the slab section and accordingly render the mode field a confined spot. This in turn improves the beam splitting performance of some conventional waveguide components such as y branches and multimode interference couplers (MMICs), in terms of the excess loss, fiber coupling loss, and compactness of these components. For a 1 x 2 y-branch beam splitter, the excess loss can be as small as 0.43 dB in the new design, which is much lower than that for a conventional rib waveguide structure (which is 1.28 dB). For a 1 x 2 MMIC in our example, the new rib waveguide structure presents an excess loss of 0.064 dB for the TE mode and 0.046 dB for the TM mode, with negligible nonuniformity in dimensions of 30 microm x 1040 microm, whereas its counterpart (i.e., the one with the same dimensions but without a thin-film layer) presents an excess loss of approximately 0.86 dB for both modes. A conventional MMIC must have dimensions larger than 70 microm x 5650 microm to maintain almost the same low excess loss. 相似文献
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采用全矢量有限元法,仿真设计了一种工作在2.5THz频段的中空芯太赫兹光子晶体光纤,用环烯烃聚合物材料(COC)制备了光纤样品,利用CO2激光泵浦气体太赫兹源搭建了测试平台并对光纤的太赫兹波传输性能进行了测试。实测光纤最低损耗0.17dB/cm、平均损耗约0.5dB/cm,在弯曲90°情况下光纤传输损耗波动小于5%,具有良好的可弯曲性;光纤输出端口的模场分布测试结果表明,光纤是以主模进行传输,太赫兹能量很好地被束缚在光纤芯中。 相似文献
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We propose and numerically analyze a novel mode converter based on two-dimensional photonic crystal waveguides with square arrays of cylindrical dielectric rods in air. The mode converter uses small perturbation defects to decouple various modes in the multimode waveguide, thereby permitting propagation of only one mode at any given frequency, which permits one-to-one mode conversion without exciting unwanted modes. The mode converter can efficiently convert a TM0 mode supported in a single-mode photonic crystal waveguide into a TM2 mode supported in the multimode waveguide that is laterally coupled to the single-mode waveguide section for a wide wavelength range. Influences of different sizes and positions of perturbation rods on the band structure of the multimode waveguide are studied. 相似文献
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Abstract A proposal for a new single-mode optical fiber design technique with ultra-low bending loss applicable in fiber-to-the-home operation is presented. The suggested design method is based on reverse problem engineering, which evaluates the refractive index profile. The most remarkable feature of this methodology is designing a bend-insensitive fiber without core radius and mode field diameter reductions. The designed structures exhibit ultra-low bending loss and high effective area simultaneously. Meanwhile, the residual stress of the designed structures is small due to gradual variation of the refractive index in the core region. Simulation results show a bending loss of 4.3 × 10?4 dB/turn at 1.55 μm for a single turn of 5-mm radius. 相似文献
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强激光与气体的长距离相互作用能产生许多新奇的物理效应,而自由空间光束的自聚焦、衍射、散射等问题限制了该科技领域的发展。本文提出了一种新型多孔芯光子晶体光纤,纤芯亚波长、低折射率空气孔可以传光,具有宽带、低损耗、单模传输特性。利用倏逝波耦合效应,研究了纤芯亚波长空气孔束缚光的原理。根据光波传输的电磁场理论,分析了低折射率空气孔中的光强增大效应。强光在空气孔中长距离传输,为光与物质的相互作用提供了新条件,可以用于气体传感、非线性光学、高集成光子技术、原子操控等。由于纤芯空气孔可以传光,改变空气孔的大小,直接影响模场分布,进而可以获得很高的结构双折射。通过光纤结构参数的合理设计,分别获得了B=4×10-2的高双折射、纤芯直径5 μm的大模场高双折射、大模面积单偏振单模特性,在光纤偏振器、光纤滤波器、光开关及光纤传感等领域有广泛的应用前景,为新型光场调控提供了新方法。 相似文献
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本文报导一个单模光纤与单模Ti扩散LiNbO3光波导的端面耦合及固定连接实验研究.利用电弧烧熔法在单模光纤端面上制成了微透镜,改善了模场匹配程度,采用二维硅V形糟,提高了光纤与波导的对准精度。 相似文献
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Starting with two dimensional, scalar wave equation, a variational equation was established for the fundamental TE and TM modes guided in Ti:LiNbO3 waveguides on the basis of assuming a symmetric Gaussian mode field function in the width direction and two-half Gaussian trial functions in the depth direction. The controllable waveguide fabrication parameters, including channel width, diffusion temperature, initial Ti-strip thickness and diffusion time, dependent of fundamental mode size, effective pump area, coupling efficiency between pump and laser modes, and the coupling loss between a Ti:LiNbO3 waveguide and a fiber were numerically calculated for Z-cut Er:Ti:LiNbO3 channel waveguide lasers at three possible emission wavelengths 1532,1563 and 1576 nm and two possible pump wavelengths 1480 and 980 nm. The calculated results were compared with those of Gaussian/Hermite–Gaussian mode field distribution in detail. 相似文献
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Uwe Langbein Udo Trutschel Andreas Unger Michel Duguay 《Optical and Quantum Electronics》2009,41(4):223-233
A rigorous mode solver for multilayer fiber configurations using a Constraint Optimization method is presented. For an arbitrary
number of dielectric or metallic layers the cylindrical wave equations are solved exactly. The transition between the different
layers implies a coupling of all field components. Case examples of three unconventional fiber structures (Air-ARROW-fiber,
metal-coated fiber, core to ring fiber coupler) are presented. Mode dispersions charts and field characteristics are calculated
to demonstrate the performance of the constraints optimization method applied. 相似文献
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We analyze a dielectric waveguide with a photonic crystal core. Using constant frequency contour analysis, we show that the modal behavior of this structure is drastically different from that of a conventional slab waveguide. In particular, at a given frequency the lowest-order guided mode can have an odd symmetry or can have more than one nodal plane in its field distribution. Also, there exist several single-mode regions with a different modal profile in each region. Finally, a single-mode waveguide for the fundamental mode with a large core and strong confinement can be realized. All these behaviors are confirmed by our three-dimensional finite-difference time-domain simulations. 相似文献