Light Localization in Slot Photonic Crystal Waveguide

A single-mode photonic crystal waveguide with a linear tapered slot is presented, which can localize light spatially by changing the slot width. Its effective bandwidth is 52nm, from 1500nm to 1552nm. Along the tapered structure, the slot width is reduced, and the corresponding band curve shifts. The group velocity of light becomes zero at the band edge. Therefore, different frequency components of the guided light are slowed down and finally localized at correspondingly different widths inside a tapered slot photonic crystal waveguide. Furthermore, this structure can confine light wave in a narrow slot waveguide, which may effectively enhance the interaction between light and the low-index wave-guiding materials filled in the slot.     

Optical Tamm States in Dielectric Photonic Crystal Heterostructure

We investigate one-dimensional dielectric photonic crystal and optical Tamm modes formed by superposition of two band gaps and find that this kind of mode can be explained by the single negative materials tunnelling effect. A finite-size dielectric photonic band gap can mimic one kind of effective single negative material and this property sensitively depends on the frequency location in stop-band regions and surface termination and so on. The effective impedance match and effective phase match give the precise position of the optical Tamm mode. Complete transparency via tunnelling is achieved by two opaque media and demonstrates the validity of our approach.     

一种硅基金属狭缝表面等离子体波导的设计

设计了一种适用于光电子集成电路的表面等离子体波导结构.利用三维全矢量时域有限差分法对该波导结构进行了数值模拟,并分析了其在基模传输时的模式场分布与金属结构顶角的关系以及其能量限制性.研究了该波导结构在不同金属材料下的有效折射率和传播长度对芯层宽度的依赖关系,讨论了两个该波导结构之间的耦合长度、最大转移功率和彼此间的串扰.结果表明:光场被高度限制在芯层区域,在金属结构顶角为135°时,其能量限制因子更高;在金属材料确定的情况下,有效折射率随芯层宽度增大而减小,而传播长度增大;在芯层宽度一定的条件下,两个波导结构间的耦合长度随波导间距增大而增大,最大转移功率和串扰随波导间距增大而减小.     

Distinguishing the Topological Zero Mode and Tamm Mode in a Microwave Waveguide Array

The Su–Schrieffer–Heeger (SSH) model has been the subject of extensive experimental research in the context of topological photonics. Ideally, the on‐site potential and hopping strength are sufficiently accurate for implementation in photonic coupled waveguide arrays. Here, two localized edge modes, the topological zero mode and trivial Tamm mode, are proposed and demonstrated in the modified SSH model using a microwave photonic waveguide array. The system used is composed of an array of evanescently coupled ultrathin corrugated metallic “H‐bar” waveguides. Furthermore, the differences between the zero mode and Tamm mode are clearly demonstrated by microwave near‐field experiments on the coupling behavior along the propagation direction for 40 cm at the excitation frequency of 17 GHz. These findings should deepen the understanding of localized edge mode confinement mechanisms, both in coupled waveguide array systems and other topological or quantum systems.     

Waveguide Bragg mirror with negative differential characteristic

The dependence of Bragg mirror efficiency on the grating depth or the amplitude of the grating harmonic is investigated and shown to be similar to theI-V characteristic of a tunnel diode.     

Self-aligned Coupled Waveguide Distributed Bragg Reflector Lasers

A novel self-aligned coupled waveguide (SACW) multi-quantum-well (MQW) distributed Bragg reflector (DBR) laser is proposed and demonstrated for the first time. By selectively removing the MQW layer and leaving the low SCH/SACW layer the Bragg grating is partially formed on this layer. By optimizing the thickness of the low SCH/SACW layer, a～80% coupling efficiency between the MQW gain region and the passive region are obtained. The typical threshold current of the SACW DBR laser is 39 mA, the slope efficiency can reach to 0.2 mW/mA and the output power is more than 20 mW with a more than 30dB side mode suppression ratio.     

Coaxial Waveguide Slot Bridge Cell for Liquid Substances Study

The experimental method suggested suppose the studying of energy characteristics of slot bridge (SB) cells in the multi mode operating regime based on the preliminary numerical investigation of scattering resonant characteristics of SB (solution of boundary value problem and investigation of eigen frequencies and relevant field modes). The configuration of experimental model of SB cell is computed accordingly to required frequency band and preliminary information about dielectric parameters of materials chosen for tests. Ethanol scattering characteristics of SB cell are computed by software, developed on the base of rigorous solution of the boundary value problem, providing numerical data with any required accuracy.     

多参量可调谐的Bragg波导光栅滤波器设计(英文)

为了解决基于光纤布喇格光栅和压电陶瓷结构的任意光脉冲整形器在动态调谐时存在不足的问题,提出并设计了一种波长、相位、幅度参量独立可调的Bragg波导光栅滤波器,以实现谐振波长及谐振波相位快速独立的线性调控.理论分析表明:波长和相位的理论调谐效率分别为15.6pm/V和0.2π/V,滤波器的输出光强度可以通过偏振旋转器控制.基于转移矩阵理论的仿真分析发现:该滤波器在蚀刻占空比为1/2时反射率最大,光栅长度为10.869mm,蚀刻深度大于100nm时,可以获得98.4%以上的反射率和大于0.14nm的带宽;增大波长调谐电压会进一步降低滤波带宽.     

基于光子晶体塔姆态的带隙分裂

将由两个一维介质层光子晶体组成的异质结拓展为超晶格结构,分析了该结构的能带和透射谱。该超晶格结构可以产生多个界面隧穿态,它们之间的耦合可产生新的通带。研究结果表明,该通带的宽度随光子晶体的周期数变化,而通带的中心位置保持不变。当光子晶体周期数取特定值时,这个通带将发生分裂,在带间产生零相位带隙或π相位带隙。     

布拉格反射波导激光器的光谱特性（英文）

设计并制备了基于双边非1/4波长布拉格反射波导的边发射半导体激光器,中心腔采用低折射率材料,在垂直方向利用布拉格反射进行光限制,实现了超大光斑尺寸且稳定单横模工作。10μm条宽、未镀膜的脊型激光器在准连续和连续工作方式下的总的输出功率分别超过了170 mW和80 mW,且最高功率受热扰动限制。激光器远场图案在垂直方向为双瓣状,单瓣垂直方向和水平方向发散角分别低至7.85°和6.7°。激射谱半高全宽仅为0.052 nm,光谱包络存在周期性调制现象,模式间隔约为3.3 nm。电流增加到300 mA以上时,激光器出现模式跳变。     

A 60-GHz Wideband Slot Antenna Based on Substrate Integrated Waveguide Cavity

This paper proposes a new wideband W-band substrate integrated waveguide (SIW) cavity-backed slot (CBS) antenna. The SIW cavity suppresses the backward radiation and ensures this antenna have a very low profile (only about 4% of the operating wavelength). Several techniques, such as slot resonator with semicircular end, quarter-wavelength microstrip resonator, are introduced to improve impedance matching. The studied results demonstrate that this antenna has wide operating bandwidth in 54.3–67 GHz (about 20.9% of the fractional bandwidth), unidirectional radiation pattern and good linear polarization characteristic. These properties are very suitable for RF front-end system-on-package (SoP) design in millimeter wave wireless communication systems. This work was supported by the National Nature Science Foundation of China (60501011, 90505001), the Specialized Research Fund for the Doctoral Program of Higher Education of China (No. 20060614005) and the Creative Research Team Program of UESTC.     

掺铒聚合物狭缝波导放大器的增益特性研究

设计了一种高浓度稀土铒掺杂聚合物填充硅狭缝结构的平面光波导放大器（工作波长1 550 nm,泵浦波长1 480 nm）,能够在低泵浦下获得高增益,可以应用于硅基光互联的损耗补偿。通过扫描电镜照片观察发现,合成的铒掺杂聚合物材料具有良好的纳米狭缝填充能力。考虑铒离子的合作上转换和激发态吸收,利用铒离子四能级跃迁模型,建立原子速率方程和光功率传输方程,数值仿真分析了聚合物光学性质、狭缝波导结构参数及信号光泵浦光功率等放大器增益特性的影响因素。这种具有纳米截面尺寸的光波导放大器,获得4.5 dB的信号光相对增益仅需要1.5 mW的泵浦光,展现了良好的集成光学应用前景。为了进一步提高增益,引入了多层狭缝结构,四层狭缝波导的重叠积分因子比一层狭缝的高42%。     

Defect Mode in Microwave Waveguide Bragg Structures with Metal Pins

Technical Physics - A waveguide Bragg structure containing equidistant cylindrical pins that are galvanically coupled to a wide wall of the waveguide is used to implement frequency response...     

Direct excitation of the Tamm plasmon-polaritons on a dielectric Bragg reflector coated with a metal film

Tamm plasmon-polariton is a surface state or surface wave formed at the boundary between a metal and a dielectric Bragg reflector. In order to directly excite the Tamm plasmon-polaritons with unit transmission, we design a structure of Bragg reflector coated with a metal film. Through the Bloch theorem of periodic structures and transfer matrix method, we deduce the existence conditions of the Tamm plasmon-polaritons. For a a finite structure, the Tamm plasmon-polaritons can be excited, which is dependent on the thickness of metal, the period number of the Bragg reflector, the incident direction and frequency. On proper conditions, a perfect transmission for the Tamm plasmon-polariton mode can be achieved without the use of attenuated total reflection prism coupling or diffraction grating.     

一种基于布拉格反射波导的表面等离子体激光光源（英文）

设计了一种基于布拉格反射波导的新型表面等离子体激光光源。这种光源结构简单,便于集成,可以在室温电泵浦的条件下工作,同时可以输出约毫瓦量级的表面等离子激光,相比于文献报道中纳米尺度的纳瓦级表面等离子体激光光源要高很多。该表面等离子体激光光源发射波长为808 nm,布拉格反射波导所提供的倾斜激光光线在我们设计的准Otto模型中可以直接耦合成为表面等离子体。     

Generation of NOON States in Waveguide Arrays

A method to generate NOON states with three photons by injecting photons in an array of three waveguides is presented. Conditional measurements project the wave function in a given (desired) state. In passing, it is shown how the array of three waveguides, that effectively reproduces the interaction of three fields, may be reduced to the interaction of two fields.     

SiO2波导布拉格器件中声表面波及声光相互作用分析

针对SiO2光波导声光布拉格器件,计算了SiO2非对称平板波导TE模式的横向场分布;给出了SiO2/ZnO/Air层状介质结构的性能方程、运动方程和麦克斯韦方程,推导出这种层状结构的特征方程,并结合所满足的边界条件,得到了各层介质的位移及电磁场分布;计算了声表面波所引起的光学相对介质隔离率张量的变化,最后讨论了声光衍射效率和光场与声场的重叠积分、声功率、声频率、声孔径和光波导参数之间的关系。结果表明,在低频范围内光场与声表面波场重叠良好;低阶模的重叠积分始终大于高阶模重叠积分,最低阶模与声表面波相互作用最强,所需声功率最小;当声功率一定时,增加声孔径可以提高衍射效率。     

金属介电常数的色散模型对光学Tamm态的影响

比较银介电常数三种色散模型对光学Tamm态的影响,根据三种色散模型的复折射率随波长的变化研究银-光子晶体-银结构TE波和TM波的光学Tamm 态随入射角、银层厚度及周期数的变化.得出：三种色散模型下银-光子晶体-银结构中都会出现两个光学Tamm 态（OTS1和OTS2）.三种色散模型下的光学Tamm 态的波长随入射角、银层厚度及周期数的变化规律一致.但是光学Tamm 态的透射峰值随入射角、银层厚度及周期数的变化规律不一致.Drude-Lorentz模型和Lorentz模型能够描述银的特征,而Drude模型不能.     

用于折射率传感的聚合物基狭缝波导的模拟与制备

设计了在极近红外波段(890 nm)的聚合物基狭缝波导微环折射率传感器.分析了波导高度、宽度及狭缝宽度对灵敏度的影响,以找到最佳的设计标准用于折射率传感.采用电子束光刻工艺制备了硅母版模,并用独特的氟化聚合物PFPE从硅母版模上成功制备了柔性软模具.采用紫外软压印工艺制备了聚合物基狭缝波导.波导的宽度和高度以及狭缝波导的宽度分别约为510 nm、830 nm和234 nm,聚合物狭缝波导残留层的厚度约为350 nm.制备的狭缝波导具有高的高宽比并与低成本批量生产工艺相兼容.