共查询到20条相似文献,搜索用时 15 毫秒
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Zhigang Zhang Jian Tang Deng Luo Ming Chen Hui Chen Haiou Li Mingsong Chen Zhiyi He Ning He Qian He 《Optik》2014
A new high birefringence photonic crystal fiber is proposed within the terahertz frequency region. It has two types of claddings, the inner is composed of six ellipse air holes arranged in a honeycomb array and the outer surrounded by circle holes. By using the full vector finite element method with anisotropic perfectly matched layers absorption boundary condition, the birefringence, chromatic dispersion and confinement loss of the fundamental mode are evaluated. The results show that the birefringence can achieve 10−3 when the wavelength increases from 600 μm to 900 μm. This structure will provide some reference value for the designing of high birefringence terahertz photonic crystal fiber. 相似文献
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提出了一种新型高双折射的混合格子太赫兹光子晶体光纤,通过对芯区亚波长尺寸的空气孔进行多种格子组合排列,增加结构的非对称性实现高的模式双折射. 全文仿真建模采用专业的有限元计算软件COMSOL Multiphysics 4.0,结果表明:混合格子太赫兹光子晶体光纤在很宽的频率范围内都具有较高的双折射(达到10-2)和低的限制损耗,且通过改变光纤的某些参数可以灵活地控制其双折射或限制损耗特性. 相比于同类光通信波段光纤,由于太赫兹波波长较大,能够降低芯区微结构加工的难度,具有可行性.
关键词:
双折射
混合格子
太赫兹光子晶体光纤
限制损耗 相似文献
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本文将石墨烯引入到常规光子晶体中构建一种新型光子晶体, 首次从理论上严格导出了决定其能带结构的色散关系, 由于色散关系中石墨烯电导率的存在导致了它具有与常规光子晶体有所不同的特殊光学性质, 我们发现, 随着费米能增大, 低频段能带迅速向高频移动, 而高频段能带移动缓慢, 导致了常规光子晶体没有的能带压缩现象的发生, 究其原因在于石墨烯在低频段电导率迅速变化, 而高频段电导率变化缓慢, 导致能带向高频压缩, 使得光波原先允许频率变成禁止传播, 而禁止频率变成允许传播. 相似文献
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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 相似文献
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S. Li H.-W. Zhang Q.-Y. Wen F.-M. Bai W.-W. Ling Y.-s. Xie Y.-X. Li 《Applied physics. B, Lasers and optics》2010,99(4):709-716
Using the finite-difference time-domain method, the electromagnetic field distribution of terahertz waves in different photonic
crystals Y-splitters were simulated. By continuous wave excitation of the guided mode, the simulation results show that those
different Y-splitters can divide the power in an input wave guide equally between two output waveguides. By pulse excitation
of a Gaussian envelope in time, the different Y-splitters have large different amplitude-frequency characteristics. The improved
Y-splitter with a rod in the junction and without rods in the corners has widest −3-dB bandwidth 0.224 THz, and the amplitude
reaches 0.616. The improved Y-splitter has better performance than other Y-splitters. These results provide a useful guide
and a theoretical basis for the developments of terahertz functional components. 相似文献
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Ultrahigh-quality photonic crystal cavity in GaAs 总被引:3,自引:0,他引:3
Membrane-based photonic crystal GaAs cavities with a double-heterostructure design were investigated. They show the highest quality factors for GaAs photonic crystal cavities to date, exhibiting quality factors higher than 10(5). The resonances of these cavities were fine-tuned in steps smaller than 2 nm by digital etching. 相似文献
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A lateral cavity photonic crystal (PhC) surface-emitting laser is realized on a commercial epitaxial waveguide wafer without a distributed Bragg reflector first. Energy is coupled from the lateral resonance to surface-emitting light through the Γ band edge of the PhC with a square lattice. Electrically driven 1553.8?nm surface-emitting lasing action is observed at room temperature. The threshold current density of 667?A/cm2 is ultralow for the surface-emitting laser. 相似文献
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Highly tunable photonic crystal filter for the terahertz range 总被引:1,自引:0,他引:1
By use of an incipient ferroelectric, SrTiO3, as a defect material inserted into a periodic structure of alternating layers of quartz and high-permittivity ceramic, thermal tuning of a single defect mode over the entire lowest forbidden band was obtained. The tunability of this compact structure reached 60%. 相似文献
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We report an experimental demonstration of the superprism effect in a photonic crystal slab at terahertz frequencies. For a 10% frequency variation around 0.28 THz, the refraction angle at the output facet of a wedge-shaped photonic crystal varies by about 15 degrees. A comparison with the predictions of a band structure calculation demonstrates that a three-dimensional treatment, accurately modeling the finite slab thickness and the metallic boundary conditions, is required for even a qualitative agreement with the experimental observations. 相似文献
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J. Z. Xin K. L. Jim J. Yang X. J. Gong L. Q. Chen F. Gao Y. H. Tsang H. L. W. Chan C. W. Leung 《Applied Physics A: Materials Science & Processing》2012,107(1):109-115
A one-dimensional photonic crystal working in the terahertz (THz) range was designed and implemented. To facilitate the design,
the transmission properties of strontium titanate crystals were characterized by THz-time-domain spectroscopy. Relatively
high refractive index (∼18.5) and transmission ratio (0.08) were observed between 0.2 to 1 THz. A stacked structure of (Si
d
Si/STO d
STO)
N
/Si d
Si was then designed, with transmission spectra calculated by the transfer matrix method. The effects of the filling ratio (d
STO/(d
Si+d
STO)), periodicity (d
Si+d
STO) and the number of repeats N on the transmission of PC were investigated. The effect of introducing a defect layer was also studied. Based on these, Si/STO
multilayers with STO defect thickness of 125 μm and 200 μm were measured. The shift of the defect mode was observed and compared
with the calculations. 相似文献
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A novel high birefringence polymer photonic crystal fiber (PCF) is proposed in this work. This PCF is composed of a polymer core and a cladding with elliptical air holes and squeezed triangular lattice. The high birefringence is introduced on the combined effect of elliptical air holes and the squeezed lattice. Our numerical results based on the supercell lattice method indicate that the birefringence can reach as high as 0.0018 at 650 nm wavelength with a properly designed cladding structure. We also analyze the dependence of the birefringence on structure parameters. And we design a PCF that has high and flattened birefringence. 相似文献
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设计了一种缺陷模迁移光子晶体微腔全光开关. 两条二维三角晶格空气孔光子晶体波导由一个光子晶体微腔连接, 在微腔的点缺陷中填充掺有少量偶氮聚合物的苯乙炔类液晶. 通过调节控制光的偏振态, 使偶氮聚合物发生顺-反异构化反应, 带动液晶分子重新取向, 从而改变光子晶体微腔的谐振波长, 进而实现光的通过与截止. 运用时域有限差分法和平面波展开法分析 了二维光控液晶光子晶体微腔全光开关的光学特性. 数值计算结果表明: 对于1.55 μ通信波段通过外界偏振光控制所填充的向列相液晶 的折射率可以实现对光波的导通与截止. 分析结果显示, 此开关具有阈值低, 消光比较大, 体积小等优点.
关键词:
二维光子晶体微腔
波导
时域有限差分(FDTD)
液晶 相似文献
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Jiu-sheng Li 《Optik》2014
We design an ultra-fast terahertz wave switch based on T-shape photonic crystal waveguide. The polymer rod is added in the junction as a point defect, the refractive index of which can be varied by adjusting the external pump laser intensity. The transmission spectrum is calculated by finite-difference time-domain method, which shows that the output energy of the two output ports is closely related to the refractive index of the polymer rod. By continuous wave excitation of the guided mode, the simulation results show that the T-shaped photonic crystal waveguide can flexibly tune the power in two output ports. The tuning rate of the device is about 0.3 ns. These results provide a useful guide and a theoretical basis for the developments of terahertz wave functional components. 相似文献
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Zhaolu Diao Christopher Bonzon Giacomo Scalari Mattias Beck Jrme Faist Romuald Houdr 《Laser \u0026amp; Photonics Reviews》2013,7(5):L45-L50
Compact semiconductor light sources with high performance continuous‐wave (CW) and single mode operation are highly demanded for many applications in the terahertz (THz) frequency range. Distributed feedback (DFB) and photonic crystal (PhC) quantum cascade (QC) lasers are amongst the leading candidates in this field. Absorbing boundary condition is a commonly used method to control the optical performance of a laser in double‐metal confinement. However, this approach increases the total loss in the device and results in a large threshold current density, limiting the CW maximum output power and operating temperature. In this letter, a robust surface emitting continuous‐wave terahertz QC laser is realized in a two‐dimensional PhC structure by a second order Bragg grating extractor that simultaneously provides the boundary condition necessary for mode selection. This results in a 3.12 THz single mode CW operation with a 3 mW output power and a maximum operation temperature (Tmax) of 100 K. Also, a highly collimated far‐field pattern is demonstrated, which is an important step towards real world applications. 相似文献
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We present a way to selectively tune the properties of the degenerated modes confined in a single point defect two-dimensional photonic crystal cavity based on a triangular lattice of air holes. We investigate the dependence of the modal properties of the resonator on the position of the first neighbor holes, showing that it is possible to finely tune the resonant frequency of only one of these two modes and to increase the quality factor of the mode that has no frequency shift. This is achieved by controlling the wavevector components inside the cavity. This approach is a viable strategy for the development and the optimization of several innovative devices based on bi-modal cavity arrays, such as arrays of integrated optical filters and optical read-out sections for biosensing applications. 相似文献
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A high quality-factor (Q) cavity based on a one-dimensional (1D) photonic crystal with gradated elliptical holes was designed using FDTD simulation. Different gradient profiles of the mirror holes were found to correspond to different Q- values of the cavities. A simple strategy is proposed to construct high-Q cavities by using an S-shaped gradient profile for the elliptical holes' minor axes, such as a cosine function or Gaussian function. Using such a strategy, a Q value exceeding two million is obtained with only ten mirror holes in a cavity. 相似文献