共查询到20条相似文献,搜索用时 453 毫秒
1.
In this work, the beam splitter with two input ports and two output ports in two-dimensional photonic crystals is studied through the finite-difference time-domain method. The beam splitter consists of two orthogonally cross line defects. The diameter of the two diagonal air holes at the intersection of the two line defects was modified. The input light can be identically divided into the two output ports. The beam splitters can be applied in the photonic crystal Mach-Zehnder interferometers or photonic crystal optical switches. 相似文献
2.
Swift GP Gallant AJ Kaliteevskaya N Kaliteevski MA Brand S Dai D Baragwanath AJ Iorsh I Abram RA Chamberlain JM 《Optics letters》2011,36(9):1641-1643
We demonstrate how micromachined photonic crystals can be used to negatively refract terahertz frequency light. The photonic crystals, which are constructed from conventional dielectric materials, manipulate the incident beam via interaction with their photonic bands. Consequently, we show that different components of a broadband beam incident on the structure may be positively or negatively refracted, depending upon its frequency and that the structure can be used as an effective spectral filter of THz radiation. 相似文献
3.
Yu Qian Ye Jian Qi Shen Yi Jin 《Applied Physics A: Materials Science & Processing》2008,93(2):505-509
The band structures and equifrequency contours of one-dimensional photonic crystals (PCs), which consist of an electromagnetically
induced transparency (EIT) medium and a common dielectric medium, can be dramatically changed by tuning the coupling field
intensity (or coupling Rabi frequency, CRF) of the EIT medium. It is found that for a probe light at a fixed frequency, either
positive or negative refraction in the EIT PC can be realized with a proper CRF. The behavior of a Gaussian beam (probe light)
obliquely incident on such an EIT PC slab is simulated numerically. The probe light beam transmitted from the slab can be
shifted transversely in a large range, and negative refraction enhances this effect. The present scenario can be applied in
some areas such as quantum optical and photonic device designs. 相似文献
4.
Dielectric microspheres can confine light in a three-dimensional (3D) region called photonic nanojet is shown when they are illuminated by different polarized beams. The influence of incident light polarization on photonic nanojet using the finite-difference time-domain (FDTD) method is demostrated. The axial field intensity profiles of photonic nanojets for both the linear and circular polarization incident beams are very similar. Azimuthal polarization incident beam induces a doughnut beam along the optical axis, while the radial polarization incident beam permits one to reach an effective volume as small as 0.7(λ/n) 3 . 相似文献
5.
将石墨烯中赝磁场的产生机理运用于光子石墨烯,通过在光子石墨烯中引入晶格有规律单轴形变的方式,理论分析得到了谷依赖的均匀赝磁场,并通过数值模拟的方法观察到明显的谷霍尔效应.这种谷霍尔效应的显著程度随晶格形变度的增加而加强.在具有一定损耗的电介质材料构成的形变光子石墨烯中仍可观察到明显的谷霍尔效应.随着电介质材料损耗的增加,谷霍尔效应导致的波束转弯效果依然能够保持,只是强度逐渐变弱.类似于自旋电子学中的自旋霍尔效应,这种光子石墨烯中等效赝磁场作用下的谷霍尔效应在未来谷极化器件的设计和应用中具有重要意义. 相似文献
6.
将耦合波导列应用于光子晶体单模波导,提出一种提高光辐射的光子晶体结构. 基于时域有限差分方法的理论研究表明,当将耦合波导列附加到单模光子晶体波导出口端的适当位置,使出射光分成若干强弱不一的光束,这些光束在传播空间通过干涉形成一定程度的汇聚,大大提高了光子晶体波导在水平方向的光辐射效率. 另外,当耦合波导列的行数大于某固定值(2N=8)时,辐射质量基本保持不变,由此可获得最紧凑的器件结构. 这种类型光子晶体在近场光学和集成光学等诸多方面有潜在的应用价值.
关键词:
光子晶体波导
光辐射
波导列
耦合波导 相似文献
7.
Berrier A Mulot M Swillo M Qiu M Thylén L Talneau A Anand S 《Physical review letters》2004,93(7):073902
We report on the first experimental evidence of negative refraction at telecommunication wavelengths by a two-dimensional photonic crystal field. Samples were fabricated by chemically assisted ion beam etching in the InP-based low-index constrast system. Experiments of beam imaging and light collection show light focusing by the photonic crystal field. Finite-difference time-domain simulations confirm that the observed focusing is due to negative refraction in the photonic crystal area. 相似文献
8.
Yongjin Wang Yoshiaki Kanamori Hongbo Zhu Kazuhiro Hane 《Photonics and Nanostructures》2012,10(1):146-152
We present here the fabrication and characterization of single layer silicon photonic crystal mirror on a silicon-on-insulator wafer. By a combination of electron beam lithography, fast atom beam etching with deep reactive ion etching, silicon photonic crystal slabs are achieved on 260 nm freestanding silicon membrane and sandwiched with air on the top and bottom. Their high refractive index contrasts enable photonic crystal slabs function as dielectric mirrors for externally incident light. The optical performances of fabricated photonic crystal slabs can be tuned by varying the width of separation grooves or the air-hole size, which represents a significant advantage of offering various approaches for optical response control. 相似文献
9.
10.
Xiaoliang Ma Yinghui Guo Mingbo Pu JinJin Jin Ping Gao Xiong Li Xiangang Luo 《Annalen der Physik》2020,532(1):1900396
Optical hook, a kind of curved high-intensity light beam, has aroused tremendous interests during the past several years, and its experimental observation has been reported in the terahertz band. The existing approaches to generate such beams depend on the effect of “curved photonic nanojet” stemming from transparent and symmetry breaking high-index dielectric slab, and thus are restricted by the limited material selection, large device footprint, and fixed trajectory. Herein, the generation of photonic hooks in the visible band based on ultra-thin metalenses is reported. The strategy can overcome the limitations mentioned above and the photonic hook can be easily tuned by changing the incidence angle or wavelength. Such flexibility is likely to widen the future applications of such unique beam in particle trapping, optical tweezers, and superresolution imaging. 相似文献
11.
12.
LIU Sheng ZHANG Peng XIAO FaJun YANG DeXing&ZHAO JianLin Institute of Optical Information Science Technology Shaanxi Key Laboratory of Optical Information Technology School of Science Northwestern Polytechnical University Xi’an China 《中国科学G辑(英文版)》2009,52(5):747-754
The diffraction and refraction of light beam in optical periodic structures can be determined by the photonic band-gap structures
of spatial frequency. In this paper, by employing the equation governing the nonlinear light propagations in photorefractive
crystals, we study the photonic band-gap structures, Bloch modes, and light transmission properties of optically induced planar
waveguide arrays. The relationship between the photonic band-gap structures and the light diffraction characteristics is discussed
in detail. Then the influence of the parameters of planar waveguide arrays on the band-gaps structures, Bloch modes, and linear
light transmissions is analyzed. It is revealed that the linear light transmission properties of waveguide arrays are tightly
related to the diffraction relationships determined by band-gap structures. And the Bloch modes corresponding to different
transmission bands can be excited by different excitation schemes. Both the increases of the intensity and the period of the
array writing beam will lead to the broadening of the forbidden gaps and the concentration of the energy of the Bloch modes
to the high-index regions. Furthermore, the broadening of the forbidden gaps will lead to separation and transition between
the Bloch modes of neighboring bands around the Bragg angle. Additionally, with the increase of the intensity of the array
writing beams, the influences from light intensity will tend to be steady due to the saturation of the photorefractive effect.
Supported by the Youth for Northwestern Polytechnical University (NPU) Teachers Scientific and Technological Innovation Foundation,
the NPU Foundation for Fundamental Research, and the Doctorate Foundation of NPU (Grant No. CX200514) 相似文献
13.
Kuramochi E. Notomi M. Kawashima T. Takahashi J. Takahashi C. Tamamura T. Kawakami S. 《Optical and Quantum Electronics》2002,34(1-3):53-61
We propose two photonic crystal structures that can be created by combining nanolithography with alternating-layer deposition. Photonic band calculations suggest that a drilled alternating-layer photonic crystal combining two-dimensional (2D) alternating multilayers and an array of vertically drilled holes may achieve a full photonic bandgap. In addition, a 3D/2D/3D cross-dimensional photonic crystal, which sandwiches a 2D photonic crystal slab between three-dimensional (3D) alternating-layer photonic crystals, should provide better vertical confinement of light than a conventional index guiding slab. Fabrication techniques based on existing technologies (electron beam lithography, bias sputtering, and low-pressure ECR etching) require very few process steps. Our preliminary fabrication suggests that, by refining these technologies, we will be able to realize photonic crystals. 相似文献
14.
15.
The finite-difference vector beam propagation method is used to simulate propagation of Gaussian light beam in a finite slab of photonic crystal. A possibility to control light flow by the change of symmetry and polarisation of the incident light beam is demonstrated. 相似文献
16.
Photonic Crystal Circuits have been widely investigated for various optoelectronics device applications. And the gratings in photonics devices are indispensable tool, which is very common for light manipulation. In this study, an interference grating structure formed by Gaussian beam interferences in photonic crystal waveguide such that having Kerr type nonlinearity is proposed and its transmission characteristics are investigated. Finite-Difference Time-Domain method is used to analyze the device characteristics. According to simulation results, the interference grating has shown special transmission characteristics that can bring tunability for photonic crystal devices. This can be an effective method for controlling optical signals in the photonic crystal for all optical switching/routing applications as a part of add/drop multiplexing. 相似文献
17.
Design of tunable surface mode waveguide based on photonic crystal composite structure using organic liquid
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
With the method of replacing the surface layer of photonic crystal with tubes, a novel photonic crystal composite structure used as a tunable surface mode waveguide is designed. The tubes support tunable surface states. The tunable propagation capabilities of the structure are investigated by using the finite-difference time-domain. Simulation results show that the beam transmission distributions of the composite structure are sensitive to the frequency range of incident light and the surface morphology which can be modified by filling the tubes with different organic liquids. By adjusting the filler in tubes, the T-shaped, Y-shaped, and L-shaped propagations can be realized. The property can be applied to the tunable surface mode waveguide. Compared with a traditional single function photonic crystal waveguide, our designed structure not only has a small size, but also is a tunable device. 相似文献
18.
19.
基于光波在直波导和复合结构光子晶体中的传播特性,结合平面波展开法和时域有限差分法,提出并讨论了一种新型的超紧凑的光子晶体偏振光分束器. 它是由输入波导,分束结构和输出波导三部分组成. 对这种结构的三角晶格光子晶体光分束器的数值计算与模拟结果表明,该结构可以实现TE模和TM模的高效大角度分离,并且在通信波段设计尺寸小,这些特性使其在未来的集成光回路中有着重要的应用前景.
关键词:
偏振光分束器
能带结构
平面波展开法
时域有限差分法 相似文献