Holo-imprinting polarization optics with a reflective liquid crystal hologram template

Liquid crystal polarization optics based on photoalignment technique has found pervasive applications in next- generation display platforms like virtual reality...     

Planar microoptomechanical waveguide switches

Planar micromechanical waveguide switches based on lateral deflection of a cantilever beam are presented. Two material systems have been used: a GaAs-AlGaAs structure with integrated waveguides and a silicon-on-insulator (SOI), with postprocessed polymeric waveguides. The switches are characterized by low actuation voltage (3-20 V), short switching times (32-200 μs), and low crosstalk (< -30 dB)     

Wave propagation in a lossy-plane waveguide

Contents The field pattern for propagation of electromagnetic energy in a waveguide consisting of a pair of lossy planes in vacuum is evaluated; the calculations lead to a transcendental equation which, solved numerically, yields a direct measure of the propagation factor. Relevant numerical results are presented in graphical form.

---

Wellenausbreitung in ebenen Wellenleitern mit Verlusten

Übersicht Die Ausbreitung der Felder in einem einfachen, ebenen, homogenen Wellenleiter mit Verlusten wurde untersucht; die Durchrechung führt auf eine transzendente Gleichung deren Wurzeln numerisch ermittelt wurden. Graphische Resultate sind ersichtlich.

     

Surface desensitization of polarimetric waveguide interferometers

Nonspecific surface binding of small protein molecules presents a major obstacle to surface biosensing techniques attempting to detect very low concentrations (< 1 pg/mm²) of large biological objects such as cells and bacteria. A new method for selective desensitization of a polarimetric waveguide interferometer eliminates the background noise from nonspecific surface binding. We demonstrate the ability to tune the phase sensitivity of a waveguide interferometer as a function of the distance of the biological or chemical analyte from the waveguide surface. This makes possible a sensor that has zero sensitivity at a particular distance where nonspecific surface binding occurs without significantly reducing the sensitivity to target larger biological species     

Polymeric optical waveguide films for short-distance opticalinterconnects

We describe three different applications of polymeric waveguide films as short-distance optical interconnects. We fabricated the waveguide films, which were 6.5 cm long and mounted in MT-compatible (MTC) connectors by passive alignment, for MM fiber systems with a 50-μm diameter graded index (GI) core. The average insertion loss of these devices was approximately 0.6 dB at 0.85-μm wavelength. We also fabricated waveguide films with a 350 mirror and an MTC connector for use as 90° out-of-plane optical deflectors, and they exhibited an insertion loss of 1 dB. Two silica planar waveguides for single-mode (SM) fiber systems were also connected by a polymeric waveguide film. Low insertion losses were obtained in both MM and SM films designed to be employed as bending waveguides. This reveals their good potential for use as practical short-distance optical interconnects     

Asymmetrical single-mode silica waveguide deposited by PECVD

Silicon oxynitride (SiON) layer and SiO₂ buffer layer were deposited on silicon wafers by PECVD technique using SiH₄, N₂O and N₂. The refractive index of SiON films measured at a wavelength of 1552 nm using a prism coupler, could be continuously varied from 1.4480 to 1.4508. Optical planar waveguides with a thickness of 6 μm and a refractive index contrast (Δn) of 0.36% have been obtained. In addition, etching experiments were performed using ICP dry etching equipment on thick SiON films grown on Si substrates covered with a thick SiO₂ buffer layer. In order to measure optical properties, a polarization maintaining single-mode fiber was used for the input and a microscope objective for the output at 1.55 μ m. A low-loss and low propagation SiON-based waveguide was fabricated with easily adjustable refractive index of core layer.     

双模双通带基片集成波导滤波器的设计

将非谐振节点与双模基片集成波导相结合,设计了一种单腔双模滤波器,具有2个传输零点和传输极点。在此滤波器的基础上,通过十字槽耦合增加一个腔体,构成了一种双层结构的双腔双模双通带滤波器,具有带内2个传输零点和带外传输零点。HFSS仿真结果表明,2个通带内回波损耗均优于20dB,插入损耗小于1dB,通带间的阻带衰减特性良好,同时其尺寸缩减大于50%,很好的实现了滤波器的小型化。     

Planar waveguide optical spectrum analyzer using a UV-inducedgrating

An optical spectrum analyzer is demonstrated using a UV-induced, chirped grating on a planar waveguide and a linear detector array. The grating provides both the dispersion with respect to wavelength and the imaging function. The spectral response has a full-width at half-maximum of 0.15 nm and a bandwidth of 7.8 nm. A chirp of -1.75 nm/cm and a 12-cm focal length were used. The design parameters are discussed in terms of the chirp, focal length and resolution. The wavelength dependence of the optimal chirp limits the resolution for small focal lengths. For longer focal lengths, the spotsize is diffraction limited and high resolution can be achieved with minimal fabrication complexity     

Semiconductor arrayed waveguide gratings for photonic integrated devices

This paper reviews recent progress of the semiconductor arrayed waveguide gratings (AWGs) and the integrated semiconductor optical devices including the semiconductor AWGs. Recent research enables us to make semiconductor AWGs with sufficiently low insertion loss and polarization dependence. Using the semiconductor AWGs as core components, the integrated semiconductor optical devices are developing by integrating with the other semiconductor devices including photodetectors, optical amplifiers, and electroabsorption modulators.     

Coplanar waveguide basics for MMIC and PCB design

In this article, basic CPW design information geared towards a practicing microwave circuit designer, including the applicability and benefits of CPW transmission line configuration, design and modeling tips, and two microphotographs of implemented CPW MMIC amplifiers are provided. Supported by the CPW geometry (coupled slotline) and modes that can occur for practical implementation of CPW (parallel-plate waveguide mode). CPW has a significant number of applications in microwave design, and we hope this brief tutorial will provide enough of an introduction to aid designers in beginning CPW design.     

Novel waveguide structures for enhanced fiber grating devices

An emerging class of fiber waveguide structures is being used to increase the functionality of fiber gratings, enabling new devices critical to the performance of next generation light-wave communications systems. These devices rely on advances in the fabrication of optical fiber waveguides, which go beyond the conventional doped silica design and fall into two general categories: 1) local modifications to the waveguide after fabrication and 2) fibers drawn with modified claddings that include nonsilica regions throughout their length. This paper provides a comprehensive review of emerging fiber waveguide structures that enhance the functionality of optical fiber grating devices. Two examples of technologies that fall into the first category are thin metal films deposited onto the cladding surface, which can be used for thermal tuning and infusion of nonsilica materials into the air regions, which change the waveguide structure and can provide enhanced tunability. The second category is typified by air-silica microstructured optical fibers, which contain air-voids that run along the length of the fiber. These fibers have unique cladding mode properties that can be exploited in fiber grating based devices     

Numerical analysis of waveguide apertures radiating into lossy media

Three numerical methods are applied to the analysis of a rectangular waveguide-fed aperture radiating into a lossy media. A novel approach, the finite element method with an impedance boundary condition, and two established methods, the moment method and the mode-matching method, are presented. The methods are compared with respect to accuracy, execution time, memory requirement, and versatility. Four aperture geometries are chosen for detailed study: the full aperture of the rectangular waveguide, and three reduced apertures. The reflection coefficient of the aperture in contact with five known dielectrics is calculated in the frequency range 8·5–11·5 GHz. The theoretical results are validated by measurements performed on an HP8510 network analyser.     

The impact of phase errors on arrayed waveguide gratings

The impact of phase errors on arrayed waveguide gratings (AWGs) due to waveguide length deviation in AWGs has been analyzed theoretically. A statistical model to estimate the influence of phase errors in silica-based arrayed waveguide multiplexers was developed, using Fourier optics and scalar diffraction theory. In addition, the insertion loss and crosstalk of AWGs caused by phase errors were analyzed. To maintain the adjacent crosstalk at less than -25 dB, a maximum standard deviation /spl sigma//sub max/ of phase errors to the design of AWGs is obtained.     

S波段高功率矩形波导定向耦合器的设计

根据Bethe小孔耦合理论,设计出在S波段(1.8～2.6 GHz)电磁波通过矩形波导宽边圆孔耦合的定向耦合器.为提高定向耦合器的方向性,孔径采用切比雪夫孔径分布.根据预定的技术指标,初步设计出等孔间距的波导定向耦合器的有关参数.在此基础上,利用仿真软件CST对小孔厚度和部分孔间的距离进行优化,大大提高定向耦合器的整体...     

矩形波导定向耦合器特性分析

根据小孔耦合理论,简单介绍矩形波导单孔定向耦合器的最佳技术指标;为了实现宽频带、弱耦合、最佳耦合平坦度、高方向性等指标,需要设计一种新型的矩形波导多孔定向耦合器,分别对耦合孔位置、耦合孔数目、端口驻波比、耦合孔分布方式及耦合孔间距等影响定向耦合器耦合平坦度、方向性指标的因素做出详细的分析,在此基础上,采用基于切比雪夫孔阵分布的矩形波导多孔定向耦合器,从而实现了全频段耦合平坦度为±0.4dB,方向性大于30dB的矩形波导多孔定向耦合器。     

Phase-dithered waveguide grating with flat passband and sharp transitions

A new passband flattening technique for waveguide grating devices is proposed and experimentally demonstrated. It uses phase dithering of grating elements to obtain a flat passband with sharp transitions while maintaining single-mode input and output waveguides. The chromatic dispersion characteristics of the device can be improved simultaneously over the passband. The theory and design method based on an iterative Fourier transform algorithm are presented in detail with simulation and experimental results. The technique can be used in both arrayed waveguide grating and echelle grating-based devices.     

Network analysis of strongly coupled transverse apertures in waveguide

Methods of field and network theory are jointly applied to the problem of transverse aperture-type discontinuities in cascade under the conditions of multimodal excitation and interaction. A space Fourier transformation (modal analysis) translates the field problem into a network problem, whereby discontinuities take the significance of Hilbert-ports à la Zemanian. When a discontinuity is considered as enclosed by an ideal cavity, representing energy storage in the ‘localized’ modes, Foster's form of the reactance matrix of the discontinuity is recovered. The relationship with the variational method in computing the resonance matrix of the ‘accessible’ modes is illustrated. Green's function of cascaded apertures is obtained by finite network analysis. A few examples of thick interacting inductive irises in cascade are numerically investigated. Results show very good agreement with experiment.     

高功率微波矩形波导衰减器的设计与实验

提出了一种高功率微波矩形波导衰减器。本设计中,衰减器是由矩形波导、Na2SO4衰减溶液以及装此溶液的石英容器组成。首先采用同轴探针法测量1.8~2.4GHz频段内Na2SO4溶液的介电常数,然后利用CST软件在1.8~2.4GHz频段内建模和仿真计算衰减量为(52±2)dB、驻波比小于1.35的衰减器。最后按照仿真得到的最优结构尺寸制作了高功率矩形波导衰减器,并对衰减器的衰减量和反射系数进行了实测和分析。为高功率微波衰减器的设计方法的研究提供了一种有效的理论和实验研究平台。