Modelling PBG devices to DWDM filters design

The fibre optic transmission systems require a bandwidth of about 25 THz in telecommunications networks, for which it is necessary to resort to dense wavelength division multiplexing (DWDM) systems. These systems need optical filters to broadcast selectively or not in a given wavelength band. A new very promising technology for these applications is the photonic crystals with forbidden bandgap (photonic bandgap (PBG)). In this paper, we propose a model of PBG devices to design DWDM filters on PBG materials. Copyright © 2004 John Wiley & Sons, Ltd.     

Dispersion relation calculation of photonic crystals using the transmission line matrix method

In this paper we present the use of the transmission line matrix (TLM) method as a modelling tool for the computation of the dispersion relation of photonic crystals (PCs). First, the formulation of a complex‐valued TLM algorithm for the implementation of the periodicity condition on the sidewalls of the simulation domain (unit cell), is presented in detail. Then, the stability issues of this formulation are analysed from energy considerations. The analysis shows that the TLM method remains unconditionally stable since the equations enforcing the periodicity condition allow for the energy to be preserved as a constant during the simulations. Finally, the complex‐valued TLM algorithm is validated by simulating two PCs and by comparing the results with those predicted by alternative methods. Copyright © 2004 John Wiley & Sons, Ltd.     

Design and numerical analysis of Zeonex-based photonic crystal fiber for application in different types of communication networks

A photonic crystal fiber (O-PCF) with a novel structure consisting of five octagonal-shaped layers of circular air holes in the cladding region and two elliptical air holes in the core region is presented for application in different communication fields for terahertz (THz) wave propagation. The O-PCF fiber is investigated using perfectly matched layers by applying the finite element method. Based on the results of the simulations, the proposed O-PCF fiber shows a low effective material loss of 0.0162 cm^?1, a higher effective area of 5.88?×?10^–8 m², a core power fraction of 80%, a scattering loss of 1.22?×?10^–10 dB/km, and a confinement loss of 3.33?×?10^–14 dB/m in the target region of 1 terahertz (THz). Due to its excellent characteristics, the proposed O-PCF fiber offers excellent transmission characteristic across a broad band of the terahertz region. Moreover, the suggested O-PCF fiber will be ideal for use in the terahertz (THz) region for different kinds of optical communication and biomedical applications.

     

太赫兹波在二维椭圆金属光子晶体的传输特性

研究了一种由金属椭圆柱构成的二维正三角晶格的光子晶体结构,并应用有限积分法对太赫兹波段TE模的传输特性进行了仿真分析。通过改变晶格常数和椭圆的长、短半轴,分析了太赫兹波段TE模在金属光子晶体中的传输特性。结果表明,椭圆柱比圆柱更容易得到大的禁带带隙,通过分组优化组合,得到了对TE模禁带带隙最宽且最佳的光子晶体结构。这为太赫兹波段的光子晶体带阻滤波器的开发与制作提供了参考依据。     

磁性胶体晶体的制备与呈色特性

通过化学合成的方法制备出被表面活性剂聚丙烯酸(PAA)修饰的Fe3O4纳米粒子,并应用透射电子显微镜、X射线衍射、磁强计及傅里叶红外光谱仪对产物进行表征,同时利用FDTD solutions光学软件对产物的呈现性能进行建模仿真。最后通过分析得到制备的胶体产物具有超顺磁性能,粒径均一,在水中具有良好的分散性,粒子分散在水中形成的胶体在外在磁场的作用下能够自组装成液态光子晶体,不同磁场大小的调节下能够呈现不同的结构色,磁场越小,颜色越向着波长大的方向偏移,同时,用软件对胶体粒子仿真得到的呈色特性与实验结果一致。这种光子晶体在结构色印刷、传感器、防伪等各个领域有广泛的应用     

光子晶体光纤的研究进展

在14篇文献的基础上，综述了光子晶体新型介质材料的能带结构、带隙产生、制备方法，对光子晶体光纤的制备技术与应用以及新的实验和理论进展作了重点介绍，对其发展前景进行了展望。     

Analysis of polarization plane rotation characteristic in 2D photonic crystal waveguide with chiral medium by condensed node spatial network

Using the photonic band gap in photonic crystals, the fundamental waveguide structures for the light wavelength range have been developed. Based on the fine structure of these many functional devices have been proposed by analytical or numerical simulation methods and the experiments of trial manufacture. In this paper, the treatment of chiral dielectric in the Condensed Node Spatial Network for the vector potential is explained, and we show the polarization plane rotation property in air‐hole and pillar type photonic crystal waveguide structures with the chiral medium substrate. Then, we show the fundamental advantage of the air‐hole type photonic crystal waveguide structure in application to a mode converter. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(1): 7–14, 2005; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20098     

An ultra-low material loss ellipse core-based photonic crystal fiber for terahertz wave guiding: design and analysis

In this research work, we report a new design model of quasi-shaped cladding areas with rotated-hexa-based elliptical shaped core areas in photonic crystal fiber (Q-PCF) for terahertz waves of communication signals. Here, we present a six-layer circular air hole in the quasi-shape of cladding regions with two layers of rotated-hexa-based elliptical shaped air holes in the core regions of the Q-PCF for analysis of communication networks in the terahertz regime. Additionally, perfectly matched layers and the finite element method based on the COMSOL software are used to design this Q-PCF. For short- and wideband communication sectors, our proposed Q-PCF is highly useful, as it reduces ultralow effective material loss (EML), confinement loss, and scattering loss in the terahertz regime. After analysis of the numerical results, our suggested Q-PCF shows an ultralow EML of 0.0159 cm^?1, power fraction in the core area of 74%, large effective area of 5.49?×?10^–8 m², confinement loss of 3.22?×?10^–12 cm^?1, and scattering loss of 1.23?×?10^–10 at 1 THz frequency. Moreover, our proposed Q-PCF demonstrates single-mode propagation by the graphical results of the V-parameter over a frequency range of 0.80–3 THz. Our results suggest, we can clearly say that the reported Q-PCF may be highly appropriate for terahertz wave propagation for many communication networks.

     

Analysis of band gap of non-bravais lattice photonic crystal fiber

This article designs a novel type of non-bravais lattice photonic crystal fiber. To form the nesting complexperiod with positive and negative refractive index materials respectively, a cylinder with the same radius and negative refractive index is introduced into the center of each lattice unit cell in the traditional square lattice air-holes photonic crystal fiber. The photonic band-gap of the photonic crystal fiber is calculated numerically by the plane wave expansion method. The result shows that compared with the traditional square photonic band-gap fiber (PBGF), when R/Λ is 0.35, the refractive index of the substrate, airhole, and medium-column are 1.30, 1.0, and −1:0, respectively. This new PBGF can transmit signal by the photonic band-gap effect. When the lattice constant Λ varies from 1:5 μm to 3:0 μm, the range of the wavelength ranges from 880 nm to 2300 nm. __________ Translated from Optoelectronic Technology, 2007, 27(4): 257–260 [译自: 光电子技术]     

Ka波段平板光子晶体波导传输特性测量

为了测量在Ka波段下空气孔型平板光子晶体波导的传输特性,提出采用从金属矩形波导将电磁波耦合进光子晶体波导并测量其传输特性的测试方案。根据两种波导传输模式的场分布,用两段介质尖劈作为电磁波从矩形波导到三角形晶格平板光子晶体波导的模式转换结构,该结构使用电磁场仿真软件找出最优结构尺寸。实验使用聚合物聚醚酰亚胺（PEI）作为介质材料,加工出实际结构,采用AV3629网络适量分析仪测试整个系统的S参数;结果在27~40 GHz之间的传输系数为？7 dB左右,将测试数据与数值结果相比较,并重新设置PEI材料的损耗参数进行仿真,最终,测试结果在损耗角正切为5×10？4的情况下与仿真数据相一致,表明本文提出的模式转换结构有效,平板型光子晶体结构在微波波段的应用打下基础。     

Ferroelectric Based Photonic Crystal Cavity by Liquid Crystal Infiltration

A novel type of two-dimensional photonic crystal is investigated for it optical properties as a core-shell-type ferroelectric nanorod infiltrated with nematic liquid crystals. Using the plane wave expansion method and finite-difference time-domain method, the photonic crystal structure, which is composed of a photonic crystal in a core-shell-type ferroelectric nanorod, is designed for the square lattice and the hexagonal lattice. It has been used 5CB as a photonic crystal core, and LiNbO₃ as a ferroelectric material. The photonic crystal with a core-shell-type LiNbO₃ nanorod infiltrated with nematic liquid crystals is compared with the photonic crystal with solid LiNbO₃ rods and the photonic crystal with hollow LiNbO₃ rods.     

高阻抗的电磁波反射表面——光子晶体的实际应用之一

以高阻抗电磁波反射表面为例 ,介绍了光子晶体的概念及其工作原理 ,综述了光子晶体在微波领域的研究进展 ,讨论了高阻抗电磁波反射表面的奇异性质及其在微波通讯领域中的应用前景。     

Fast modelling of deeply and fully etched gratings based on the Bloch–Floquet theorem

A model of deeply and fully etched gratings (also identified as one‐dimensional waveguide photonic bandgap structures), based on the Bloch–Floquet theorem, has been developed to perform a complete analysis of the electromagnetic (e.m.) wave propagation in the structure, assumed of finite extension, i.e. to determine mode propagation constants, electromagnetic field harmonics and total field distribution, transmission and reflection coefficients, total forward and backward power flow in the structure, guided power and total losses. Comparisons with other accurate numerical methods confirm the accuracy of the new one, whose main advantages are the quickness and the possibility to determine a great amount of information and figures of merit in a few seconds (for each operating wavelength). Moreover, the model allows the designer a complete view of the physical and geometrical device features, so it permits to draw design rules for optimization of photonic bandgap (PBG) waveguide device design. Copyright © 2001 John Wiley & Sons, Ltd.     

Intimate monolithic integration of chip-scale photonic circuits

In this paper, we introduce a robust monolithic integration technique for fabricating photonic integrated circuits comprising optoelectronic devices (e.g., surface-illuminated photodetectors, waveguide quantum-well modulators, etc.) that are made of completely separate epitaxial structures and possibly reside at different locations across the wafer as necessary. Our technique is based on the combination of multiple crystal growth steps, judicious placement of epitaxial etch-stop layers, a carefully designed etch sequence, and self-planarization and passivation steps to compactly integrate optoelectronic devices. This multigrowth integration technique is broadly applicable to most III-V materials and can be exploited to fabricate sophisticated, highly integrated, multifunctional photonic integrated circuits on a single substrate. As a successful demonstration of this technique, we describe integrated photonic switches that consume only a 300 /spl times/300 /spl mu/m footprint and incorporate InGaAs photodetector mesas and InGaAsP/InP quantum-well modulator waveguides separated by 50 /spl mu/m on an InP substrate. These switches perform electrically-reconfigurable optically-controlled wavelength conversion at multi-Gb/s data rates over the entire center telecommunication wavelength band.     

Current status of microplasma research

Microscale plasmas of micrometer to millimeter range have been attracting much attention in recent years. Those microplasmas generally operate at high‐pressure regions, including atmospheric pressure, and exhibit characteristics that differ from traditional plasmas at lower pressure regions in their plasma parameters and other parameters originating from their small dimensions. When those characteristics are well combined with the inherent properties of plasmas as reactive, light‐emissive and conductive/dielectric media, there appear a variety of potential applications for nano‐material syntheses, micromachining tools, microchemical analyses, photonic devices and biomaterial processing. In this article, the current status and perspective of microplasma research are reviewed from the viewpoints of plasma generation, diagnostics/simulations and new applications. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Improved transmission for photonic crystal Y-junctions

A highly efficient Y-junction based on a planar photonic crystal (PhC) platform is presented. The PhC consists of a triangular array of holes etched into GaAs/AlGaAs heterostructure. The Y-junction has smaller holes positioned at the center of the junction, giving rise to very uniform splitting and high transmission. The performance is very encouraging, with simulation transmission of approximately 50% for each arm of the Y-splitter relative to a comparable single-defect PhC waveguide.     

CHARACTERISTICS OF METAL-FERROELECTRIC-INSULATOR-SILICON DEVICES USING HFSION BUFFER LAYERS

ABSTRACT

In this work, metal-ferroelectric-insulator-silicon (MFIS) devices were fabricated using HfSiON as buffer layers and their electrical properties were studied. Ultra-thin HfSiON films were fabricated by electron-beam evaporation at room temperature and post-annealed using different parameters such as temperature, time in O₂. By annealing a 2 nm-thick HfSiON film at 800°C for 60s in O₂, a negligible hysteresis loop and small equivalent oxide thickness of 2.3 nm were obtained with a corresponding leakage current density of 6.8 × 10^{? 5} A/cm² at a voltage shifted from the flat band voltage by 1 V. In the fabrication of MFIS diodes, Sr_0.8Bi_2.2Ta₂O₉ (SBT) films with 400 nm thickness were formed by chemical solution deposition. For Pt/SBT (400 nm)/HfSiON(2 nm)/Si diodes, a memory window of 0.8 V in width was observed during double capacitance-voltage sweep between +5 and –5 V. At the same time, excellent data retention properties were observed. The high and low capacitances in the hysteresis loop were well distinguishable even after 24 h had elapsed.     

Influence of different fluoride containing electrolytes on the formation of self-organized titania nanotubes by Ti anodization

The formation of self-organized porous titania nanotubes is achieved by electrochemical anodization under specific experimental conditions. In present work, the formation of porous titania nanotubes on titanium substrates is investigated in several SO₄²⁻/F⁻ based electrolytes. The presence of some non-porous layers covering the porous layers and accompanying the pore growth is observed. We discuss in details the influence of different electrolyte composition on the structure of self-organized porous layers, investigate the conditions for ideal pore growth. SEM investigations and XRD, AES and EDX surface analyses are carried out to characterize the self-organized porous layers. The results show that using SO₄²⁻/F⁻ electrolytes with different cations can drastically influence the final morphology of the self-organized porous nanotubes. We furthermore show that the nanotubes consist of TiO₂ and that they remain unchanged when annealed.     

State and prospects of development of gradient calorimetry

The technology of heat flux measuring with the use of gradient-type sensors, which are based on natural anisotropic monocrystals and composites (heterogeneous media) containing layers of metals, alloys, and semiconductors, is described. It is found that the time constant of such sensors is from 10^?8 to 10^?9 s. The problems and prospects of using gradient calorimetry in thermal-engineering experiments and engineering practice are discussed.