The Bragg reflection waveguide directional coupler

A directional coupler formed by two Bragg reflection waveguides (BRWs) with a common finite periodic region between them is analyzed. The coupling coefficient is a sensitive function of the index difference in the periodic coupling section. This feature can lead to a novel kind of electrooptic switch. In addition, the BRW directional coupler exhibits dispersion properties characteristic of the periodic bounding media, which can be used to implement a narrowband wavelength filter and a TE polarizer     

Silicon-on-insulator asymmetric optical switch based on total internal reflection

Based on the large cross-section single-mode rib waveguide condition, total internal reflection (TIR) and the plasma dispersion effect, a silicon-on-insulator (SOI) asymmetric optical waveguide switch with transverse injection structure has been proposed and fabricated, in which the SOI technique utilizes silicon and silicon dioxide thermal bonding and back-polishing. The device performance is measured at a wavelength of 1.3 /spl mu/m. It shows that the extinction ratio and insertion loss are less than -18.1 and 6.3 dB, respectively, at an injection current of 60 mA. Response time is 110 ns.     

Total reflection optical waveguide switch

A waveguide switch based on the change in the total reflection critical angle caused by bringing a dielectric chip into contact with the waveguide surface was fabricated and a large switching angle of 22.5° for the TE0 mode was obtained.     

Optical waveguide directional coupler measurements using amicrocomputer-assisted TV camera system

Characterization of optical waveguide directional couplers using a microcomputer-assisted TV camera system is reported. A fluorescent technique is employed to visualize wave propagation in the optical waveguides, which exhibit small scattering. The method is simple and reproducible, and can be used to estimate waveguide losses and evaluate various optical devices such as waveguide lenses and waveguide interferometers on substrates. As an example of its application, parallel and nonparallel dual-chamber directional couplers and parallel triple-channel directional couplers are measured. Power transfer between the coupled channel waveguides is observed clearly, and coupling coefficients of the couplers are obtained nondestructively. The measured performance of the couplers is in good agreement with that predicted by coupled-mode analysis     

2×2 optical waveguide switch with bow-tie electrode based oncarrier-injection total internal reflection in SiGe alloy

Based on the total internal reflection and the plasma dispersion effect of SiGe alloy, a 2×2 intersectional rib optical waveguide switch with bow-tie electrode has been proposed and fabricated for the wavelength of 1.3-μm operation. The thickness of the SiGe layer is 2.6 μm and the width is 9 μm. The branch angle of the switch is 2° and the bow-tie angle is 1.5°. The on-state crosstalk is -19.6 dB, the off-state extinction ratio is 38.5 dB and the off-state insertion loss is less than 1.70 dB. The switching time is about 180 ns     

全内反射型光波导开关反射特性的分析

本文详细分析了全内反射型光波导开关的反射特性,指出反射模存在位相变化及其相对位相差。数值计算结果表明,反射TE模和反射TM模强度反射率、反射损耗,它们的位相变化及其相对位相差都与光波导开关区介质折射率改变量、损耗以及传播角有密切关系。     

Fused coupler switch using a thermo-optic cladding

An optical switch based on a single-mode fused coupler has been fabricated. The switching is achieved by a thermal refractive index change of a silicone resin cladding material in the coupling region. Fabrication details and device characteristics are described     

钛扩散铌酸锂波导多电极■β倒相定向耦合器

本文报道了我们研制的四对电极的定向耦合器.利用电极连接的不同方式,分别测试了一对电极、两对电极和四对电极三种工作状态下器件的工作特性.采用四对电极工作时,器件实现了交叉和直通两种工作状态的电调制.     

Polymeric optical waveguide switch using the thermooptic effect

An all-polymeric optical waveguide switch which uses total internal reflection from a thermally induced index barrier is discussed. Very large effective index changes ΔN=2×10^-2 were found in the polymeric waveguide. The temperature under the evaporated stripe heater was measured from the change in its resistance. The effective index change due to the temperature increase agrees well with values calculated from the deflection angles. The operation of the switch is, apart from a small waveguide dispersion effect, polarization-insensitive. Switching times of about 10 ms were measured. It should be possible to reduce them to a few milliseconds in optimized thermal designs and with regulated power dissipation in the heater     

On the use of optical waveguide techniques for internal reflection spectroscopy

A detailed analysis is presented of the absorption of energy from a thin-film dielectric waveguide by an absorbing medium that is brought into contact with one wall of the dielectric guide. It is shown that the exponential decay constant for the mode of the guide so obtained can closely approach that obtained for the free wave in the absorbing medium alone. The dependence of the attenuation on the guide parameters is examined and means for overcoming some of the problems imposed by the guidance process are discussed. It is concluded that the techniques can offer greatly enhanced sensitivity over the conventional internal-reflection spectroscopy and yet retain the attractive features of small sample volume and easy sample preparation. The technique also offers the possibility of constructing microscopic probes for the examination of spectra in otherwise inaccessible places.     

受抑全内反射的偏振分光器

概述了薄膜偏振分光器的研究现状及其主要特点,对不同于MacNeille设计原理的受抑全内反射偏振分光器进行了研究,这种偏振分光器基于受抑全内反射和薄膜干涉原理,当入射角大于临界角时,在宽波段宽角度范围内反射P偏振光,透射S偏振光。重点分析这种偏振分光器的设计原理,设计了波长范围为420￣680 nm、空气中的入射角范围为±10°、膜系的消光比为TS/TP≥1000的用于背投系统的薄膜偏振分光器。     

偏光棱镜中受抑全内反射现象的研究

由于偏光棱镜中的受抑全内反射现象的存在,导致偏光棱镜中部分o光透射,从而降低了偏光棱镜的消光比.为了尽可能的消除受抑全内反射现象带来的不良影响,本文以Glan型棱镜为例,运用薄膜光学理论,对偏光棱镜中的这种现象进行了系统的研究,理论分析和实验测试均表明:胶合层间隙越大,胶合剂的折射率越小,o光的透射比越小;在同一间隙下,波长越小,棱镜的结构角越大,o光的透射比越小,越有利于提高棱镜的消光比.     

Optical multiplication using a bisected intersecting waveguide

We present an analysis of a bisected intersecting waveguide in periodically poled lithium niobate that can produce and isolate the second-order optical product E(ω₁+ω₂)~E₁(ω₁ )E₂(ω₂) free from the near degenerate second harmonics. Model calculations of such a device fabricated in quasi-phase matched (QPM) LiNbO₃ predict a conversion efficiency of ≈1.5%/W, about 15% that of a straight waveguide of the same length, and a crosstalk of ≲-30 dB     

衰减全反射型聚合物波导光开关的实验研究

文章提出一种用衰减全反射(ATR)结构来控制光的开关效应的新型方法和装置.该光开关可利用聚合物薄膜的电光效应,通过电场控制衰减全反射结构中入射光能量到导模层的耦舍效率,实现光的开关效应.该器件具有功率损耗小、消光比大、响应速度快、稳定性好、制备工艺简单和成本低廉等诸多特点.     

Silicon p-i-n photodetector using internal reflection method

A semiconductor photodetector is proposed which makes use of an internal reflection method to enhance the photoresponse. This method is to let the incident light be multiply-reflected in the detector so that a long distance is traveled and most of the photon energy is absorbed by the detector. Theoretical analysis of the steady-state and time-dependent photoresponses for a p-i-n photodetector is presented. The photodetector is found to be particularly useful in detection of light with wavelengths near the intrinsic absorption edge. The photodetectors are fabricated from 4000 Ω.cm n-type, oriented silicon wafers. Both sides of the wafer are polished with one side inclined one-half degree with respect to the other. The p+n junction and the ohmic contact are formed by alloy method. The measured photoresponses for wavelengths of 1.0 and 1.1 µm are in reasonable agreement with the theoretical predictions.     

全内反射荧光技术在病毒成像中的应用和比较

目的:建立以激光为光源的全内反射荧光技术在活体病毒观察示踪的新方法。方法:分别使用普通荧光,激光共聚焦和全内反射荧光显微镜拍摄非洲绿猴肾上皮细胞上的人偏肺病毒,并对图像进行比较。结果:TIRF成像分辨率和时间分辨率上均优于传统荧光以及激光共聚焦,但只能观察到邻近培养介质的病毒,使用条件受到一定的限制。结论:全内反射荧光显微技术可以用于病毒成像,为研究病毒、细菌等病原微生物感染机制提供了直观有效的技术手段。     

Lossless optical packet multicast using active vertical coupler based optical crosspoint switch matrix

This paper investigates a novel optical multicast scheme without excess optical splitting loss to be realized using an active vertical coupler (AVC)-based optical switch matrix, due to the optical gain available in the AVC switch cells. Theoretical analysis and computer simulation have been carried out regarding the operational principle and switching characteristics of this scheme. Computer simulation further suggests that the amplified spontaneous emission (ASE)-limited scalability of the scheme can be as high as more than 40. Experiments using an existing 4 /spl times/ 4 switch-matrix device successfully demonstrated the predicted multicast switching operation. Measured switching characteristics and the optical signal-to-noise ratio (OSNR) values are in good agreement with simulation predictions. High switched-signal Q-factor values of 1-to-2 and 1-to-3 multicasting configurations indicate that the scale of the multicasting scheme can be further increased significantly.     

Semiconductor monolithic wavelength selective router using agrating switch integrated with a directional coupler

A semiconductor monolithic wavelength selective router is proposed. An electrically tunable grating switch is monolithically integrated with a directional coupler. The effect of sidelobe on the demultiplexing characteristics of the router is investigated, and it is shown that the sidelobes degrade the wavelength crosstalk and introduce a power penalty for demultiplexing characteristics. A phase-synchronized sampled grating is introduced to suppress the sidelobes, and wavelength router switching is observed in this structure. The extinction ratio is over 10 dB at a current injection of 25 mA. Using this structure, power-penalty-free wavelength selective routing at a 2.5 Gb/s wavelength-division-multiplexed NRZ random pattern is demonstrated     

Optical self-routing switch using integrated laser diode opticalswitch

A 2×2 optical self-routing switch using integrated laser diode optical switches is proposed. The switch is composed of a Benes network, which can perform large-scale switching functions using less hardware than a crossbar switch. The path each data stream takes through the interconnection network is determined by the binary bits of its destination address, and self-routing is accomplished by monitoring terminal voltage changes in gain guides induced by input optical signals which are injected into a p-n junction. Concentrated control is not necessary, and large optical multistage switches can be easily constructed because complicated electrode patterns are not necessary