光子晶体四信道波分复用器的研究

提出了一种由2-D光子晶体构成的四信道波分复用系统。该系统包括利用光子晶体的线缺陷实现的波导部分和利用光子晶体微腔实现的频率选择部分。采用时域有限差分(FDTD)方法,研究了光在含点缺陷(即微腔)和线缺陷(即波导)的光子晶体中的传输特性,并给出了仿真结果。计算结果表明,该结构可以实现波长为λ=1550nm附近的四信道波分复用。     

高效光子晶体太赫兹滤波器的设计

提出了一种新型光子晶体太赫兹(THz)滤波器,该滤波器包括利用线缺陷实现的波导部分和利用微腔实现的频率选择部分.应用平面波法(PWM)分析其带隙结构,然后应用时域有限差分法(FDTD),研究THz波在此滤波器中的传输特性,结果表明,通过改变点缺陷的结构和增大某些介质柱的半径,可以使该滤波器实现高耦合效率的单信道单频率滤波. 关键词： 光子晶体 THz波 平面波法 时域有限差分法     

基于杂质带的光子晶体矩形波形滤波器的实现

利用转移矩阵方法对基于杂质带的光子晶体矩形波形滤波器的实现进行了研究.除了可选择不同折射率的材料外,该滤波器还可通过调整光子晶体本身的结构参量来实现.对较平杂质带的形成机制做了具体的理论分析和解释,通过数值计算光子晶体原子耦合成光子晶体分子的过程,发现光子晶体原子的线宽与光子晶体分子线宽之间的相对大小是决定能否形成较平杂质带的重要参量.     

级联一维光子晶体全方位反射器的带宽最大化

理论研究了由级联一维光子晶体构成的光子异质结构的全方位透射(反射)特性.其中各级联光子晶体的高低折射率介质相同、光学厚度比不同.以两个光子晶体级联的结构为对象,利用传输矩阵方法系统研究了不同偏振态光在不同入射角时光子帯隙的变化,得出实现全方位光子带隙的最大展宽条件,即前一光子晶体的帯隙上限要和后一光子晶体的带隙下限在最大入射角时重合.分别给出了满足和不满足该最大展宽条件的级联结构的全方位带隙参量,通过对全方位带隙宽度的比较说明了满足最大展宽条件的级联结构具有最大的全方位带隙宽度.     

一种能够识别与检测金属离子的芯片

光子晶体材料因其对光子传播的调控性能而被称为“光半导体”,其研究和应用受到广泛关注。在国家自然科学基金委、科技部和中国科学院的支持下,中科院化学研究所绿色印刷院重点实验室的科研人员针对光子晶体的制备和应用开展了系统研究。他们通过结构设计,制备了具有硬核．软壳结构的乳胶粒子,进而组装了具有特殊紧密堆积结构的高强度光子晶体。利用这种具有特殊乳胶粒子结构的光子晶体实现了在高灵敏度检测、光信息存储等方面的应用。通过对乳胶粒子形貌的控制,实现了对界面浸润性的调控,并基于界面性质的调制制备了高质量超窄带隙的光子晶体。     

光子晶体异质结耦合波导光开关

以二维三角晶格光子晶体为研究对象,在该光子晶体中引入两行平行的单模线缺陷波导,以一行耦合介质柱为间距,通过调节部分耦合介质柱的折射率,构筑了光子晶体异质结耦合波导光开关结构。利用平面波展开法和定向耦合原理计算了在不同入射光频率下,缺陷波导间耦合介质柱的折射率不同时的耦合长度,确定了合适的光子晶体异质结耦合波导光开关的结构参数。利用时域有限差分法研究了该光开关中耦合介质柱的折射率变化及异质结构介质柱的位置分布对光信号输出路径的影响。结果表明,通过改变该结构中耦合介质柱的折射率可以改变光的输出路径,可实现光的开关行为。并且异质结构介质柱位置的随机分布对该光开关的影响不大,有助于光子晶体新型滤波器、定向耦合器、波分复用器以及光开关等光子器件的研究。     

光子晶体光纤的全光纤纤芯变形研究

利用有限差分光束传输法分析了全光纤纤芯变形光子晶体光纤中的模场分布以及能量损耗情况.实现了光子晶体光纤的选择性空气孔塌缩,制作了由小纤芯到大纤芯和圆形芯到矩形芯的纤芯变形光子晶体光纤,该光纤在波长1550 nm下以小于0.05 dB的能量损耗实现了光斑的整形.实验结果与模拟结果有很好的一致性. 关键词： 光子晶体光纤 空气孔塌缩 纤芯变形     

二维硅基平板光子晶体器件

硅材料在红外通讯波段具有低损耗和高折射率的特性,使得其成为集成光学领域中应用最广的材料之一.主要介绍了本课题组在二维硅基平板光子晶体中实现微纳尺度上光调控的研究进展,讨论了利用光子晶体的缺陷态实现各种集成光学器件,包括光子晶体波导、微腔和利用光子晶体波导和微腔形成的滤波器.还介绍了光子晶体中特殊的光折射现象,包括红外波...     

高质量三维光子晶体的制备及其透射谱研究

设计了简易的压强可控自组装实验装置,制备了由直径为260 nm的聚苯乙烯(PS)胶体球组成的面心立方光子晶体.分析了压强的变化对光子禁带(PBG)深度及光子带隙边缘(PBE)坡度的影响,确定了合适的压强生长环境(P=5999.5 Pa).利用该实验装置,还进行了光子晶体的小批量制备,一次性制得了三块光子晶体,并从不同角度对每一块光子晶体的透射谱及不同光子晶体的透射谱进行了测量.同一光子晶体不同位置透射谱的重合、同一批次制备的不同光子晶体透射谱的一致性及光子禁带两侧的Fabry-Pérot振荡等均说明:该装置制备的光子晶体在大区域、大面积上是高度有序、均一和平整的;利用该实验装置进行光子晶体的小批量制备是可行的.     

基于冲击波作用于光子晶体实现光学频率变换方法的分析

分析了光子晶体实现光学频率变化的方法。阐述了光子晶体光学频率变换的原理,用软件仿真了冲击波作用光子晶体的折射率变化和带隙变化,分析了冲击波速度和冲击波作用光子晶体时间的长短对光学频率变化的影响,结论表明,冲击波速度越大光学频率的变化量越大,冲击波作用光子晶体的时间越长光学频率的变化量越大。由于利用光子晶体的禁带特性,能够对落入光子晶体禁带中的光波实现全反射,故频率转换效率很高。此种方法在近几年发展起来的可调谐激光器有重要的应用,也是光子晶体一个新的研究领域。     

Fano resonance sensing based on coupled sub-wavelength dielectric grating and periodic photonic crystal

Based on the diffraction effect of sub-wavelength dielectric grating and the optical property of periodic photonic crystal, a hybrid structure of sub-wavelength grating all-dielectric multilayer thin film containing periodic photonic crystal is proposed. The transmission property of the structure is simulated by finite element method (FEM). The result shows that the discrete state generated by the sub-wavelength waveguide grating will be coupled with the continuous state generated by the photonic crystal cavity and the Fano resonance can be formed. The Fano resonance sensing model based on structural parameters and resonance wavelength are established, the influence of structural parameters on the Fano resonance spectral curve is quantitatively analyzed by numerical simulations, and the dynamic detection of the refractive index of samples is realized. The above structure can realize the optical refractive index sensing with high figure of merit (FOM) value and provide an effective theoretical reference for the formation of Fano resonance in the all-dielectric hybrid structure.     

光学厚度对一维三元光子晶体禁带特性的影响

运用光学传输矩阵理论,研究了一维三元光子晶体的禁带特性.数值模拟结果表明：最高折射率和最低折射率介质的光学厚度明显地影响其绝对禁带宽度,而较高折射率介质的光学厚度对其相对禁带宽度影响较大.与二元光子晶体相比,三元光子晶体的绝对带宽和相对带宽都远远大于二元光子晶体.     

Optical limitation in two-dimensional nonlinear photonic crystal with triangular lattice

Optical limitation in a 2D nonlinear photonic crystal (NPC) has been studied in this Letter. Since the optical limitation is due to Bragg scattering induced by the variation of nonlinear refractive index, it is sure that the optical limitation can be realized in nonlinear photonic crystal. The light propagation characteristics in a two-dimensional nonlinear photonic crystal with triangular lattice has been calculated by using the finite-difference time-domain algorithm, which is constructed by placing certain number of nonlinear dielectric rods in a linear photonic crystal. The optical limiting effects at 1.300 and 0.504 μm have been obviously obtained for TE polarization and TM polarization, respectively.     

High-Q microfluidic cavities in silicon-based two-dimensional photonic crystal structures

We demonstrate postprocessed microfluidic double-heterostructure cavities in silicon-based photonic crystal slab waveguides. The cavity structure is realized by selective fluid infiltration of air holes using a glass microtip, resulting in a local change of the average refractive index of the photonic crystal. The microcavities are probed by evanescent coupling from a silica nanowire. An intrinsic quality factor of 57,000 has been derived from our measurements, representing what we believe to be the largest value observed in microfluidic photonic crystal cavities to date.     

Type-I Weyl points induced by negative coupling in photonic crystal

Weyl points, which are the degenerate points in three-dimensional momentum space, have been widely studied in the photonic system, and show some intriguing phenomena such as topologically protected surface states and chiral anomalies. Type-I Weyl systems possess a complete bandgap, and topologically protected surface states can be excited without disturbing the bulk states.In this work, we investigate the influence of the sign of coupling coefficient on the topological property of the system and find that type-I Weyl points can be realized by introducing a negative coupling between the stacking layers of the designed photonic crystal. We propose a new strategy to construct a type-I Weyl system by stacking the hexagonal photonic lattice. Different from the topological nontrivial photonic system with a positive coefficient, the negative couplings in the photonic system are realized by adding another resonating site between stacking layers. We theoretically demonstrate that the effective coupling between the resonating sites in adjacent layers sign-flips through the judicious design of the nearest coupling strength and eigenfrequency of the additional sites. The surface states at opposite boundaries of the proposed system have opposite group velocities, which is the feature of type-I Weyl points. Our study provides a new method of exploring topologically protected photonic systems and developing possible topological devices.     

集成多通道光子晶体的设计及初步实验制备

在Fabry-Perot滤光片的基础上,通过改变双通道和通带通道光子晶体中处于不同对称中心的两种缺陷层的厚度,可使相应的通道或者通带位置进行独立的移动.通过刻蚀或者补偿,使缺陷层的厚度分别在二个维度方向上发生变化,改变入射光束与光子晶体的相对位置,即可实现通道和通带通道可调谐二维光子晶体.32个通道光子晶体的初步实验结果证明了设计方案的可行性.     

Study of transmission properties for waveguide bends by use of a circular photonic crystal

We study the transmission properties for the waveguide bends composed by a circular photonic crystal. Two types (Y and U type) of the waveguide bends utilizing the circular photonic crystal are studied. It has been shown, compared with the conventional photonic crystal waveguide bends, transmission properties for these bends can be significantly improved. Over a 6.4% bandwidth, less than 1-dB loss/bend are observed. U bent waveguide, i.e., 180° bend, can be easily realized with low loss using the circular photonic crystal.     

T-shaped optical circulator based on coupled magneto-optical rods and a side-coupled cavity in a square-lattice photonic crystal

We propose and numerically investigate a kind of high-efficiency T-shaped optical circulator in a two-dimensional square-lattice photonic crystal. In the T-shaped structure, the single-direction light transmission for 90° light-bending is achieved by coupling two magneto-optical rods. And aided with a side-coupled cavity, two paths of single-direction 90° light-bending are effectively combined, which realizes the nonreciprocal light transmission for two waveguides arranged and linked along a straight line. The optical properties of the system are investigated by finite element method. The circulator considered here can be used for isolating light reflections and improving system stabilization in designing photonic crystal integrated circuits.     

Design for directional emitter based on self-collimation photonic crystal by adding two-layer dielectric rods

We propose a novel directional emitter for achieving highly efficient beaming of self-collimated light from two-dimensional photonic crystal (PC). The structure is composed of a two-dimensional (2D) photonic crystal and two-layer dielectric rods. The finite-difference time-domain (FDTD) simulations show that the emission properties are sensitive to the distance between photonic crystal and two-layer dielectric rods. By adjusting the relative position of the two-layer dielectric rods, highly efficient beaming emission can be realized.