Photorefractive Beam splitter for Free-Space Optical Interconnections

A photorefractive beam splitter (PRBS) is introduced as an alternative to a polarizing beam splitter (PBS) for coupling optical power into reflective modulators in a free-space optical interconnection system. The PRBS uses a single diffraction grating recorded in a photorefractive material to redirect the incident laser light into the first diffraction order and onto the modulators. Reflected interconnection light not matching the Bragg angle criteria transmits uncoupled through the beam splitter. Experimental results show that the PRBS provides better, more uniform transmission for off-axis beams than the currently used PBS.     

共享存储器ATM交换机组播路由方法

提出了在Ｎ＊Ｎ共享存储ＡＴＭ交换机上增加一条高速总线的方法,使其专用于组播路由,构成Ｎ＊Ｎ＋１ＡＴＭ交换机。虽增加少许硬件,但在不增加存储器尺寸及苛求存储器速度条件下,保持了共享存储器ＡＴＭ交换吞吐率高、信元丢失率低、易于管理突发业务等特点,同时增添了共享总线ＡＴＭ交换 机易于实现组播路由的优点,软件仿真证实,该方法提高了系统的性能,尤其适用于混合业务流。     

一种容错ATM交换机仿真分析

讨论了一种容错ATM交换机结构。在该交换机中通过提供子交换单元和扩展链路来增加冗余路径的数目，该结构可以容错多个故障，并且冗余路径的数目随着交换机级数的增加而指数增长。通过仿真的方法得到了该交换机的生存概率、容错水平和费效比3个参数，可以看出该交换机容错性能和费效比高于目前文献上可查到的容错ATM交换机。     

MEMS光开关应用于机群系统光互连网络

建立了千兆位传输结构的高性能光互连网络 ,以提高计算机机群系统的网络性能 .利用MEMS 4× 4光开关和具有硬件路由功能的光互连网络PCI总线接口卡构成光互连链路 .光信号传输速率达 1Gbits/s以上 .基于MEMS的全光无堵塞光开关减少了光 电转换 ,开关方式与光信号的波长、速率和数据格式无关 .利用这种网络结构 ,可以最大限度地减少网络延迟和网络通信开销 ,提升了机群系统的总体性能 .利用MEMS 8× 8光开关设计了星型环型混合拓扑的光互连网络 .采用了具有硬件路由功能的光互连网络接口卡 ,并以Ethernet为控制网络实现了对MEMS光开光的动态配置 .分析并测试了光互连网络的通信性能 :峰值数据传输率可达 1Gbits/s ;数据量在 3Mbytes以上时 ,网络整体性能明显提高     

高速列车进出隧道瞬时速度测量实验装置

设计了一套采用光电开关测量高速列车进出隧道时速度的实验装置。详细阐述了测速的原理及该装置的结构,并给出了软件和硬件的相关设计,并对装置的精度进行了分析。     

低损耗液晶光开关器件用透明电极的制备

液晶可以用来制作光通讯系统中的光开关,液晶器件的损耗主要取决于透明电极的透射率, ITO(氧化铟锡)在可见光范围具有高的透射率,但在红外损耗较大。在测定ITO复折射率的基础上,本文借鉴光学薄膜中诱导滤光片的设计思想,设计、制备出了在红外1.5mm~1.6mm范围内高透射率的透明电极,使整个器件的损耗<0.4dB,相应的方块电阻为350W/□。     

转轴上裂纹在通过临界转速过程中的呼吸特征

为了研究复杂涡动引起的裂纹非线性呼吸行为对转子临界转速的影响,在恒速裂纹转子运动方程的基础上构建带横向裂纹Jeffcott转子的通用运动方程,对裂纹转子加速通过临界转速的过程进行了数值研究。结果表明:不平衡量方位角对临界转速有较大影响;在临界转速附近,裂纹的呼吸减弱;在恒加速过程中裂纹转子的最大响应滞后于重心转向。在转子实验台上进行裂纹转子通过临界转速的实验验证,观察数据支持理论研究结果。     

Screen-printing of Bi_2S_3 Nanowires on Silk Fabrics for the Construction of Flexible Optical Switch

正Wearable electronics has been one of the hottest research topics in recent years and fabric is regarded as a very promising substrate for the wearable units because of its excellent wearability.So far,there is no report on the construction of a fabric-based optical switch.In the present work we fabricate a silk fabric-based optical switch via screen-printing of silver interdigital electrode and Bi2S3 nanowires network layer.Bi2S3 NWs with the     

New Method for Optical Pumping of a Solid State Laser through the Use of Light Fibres

The present work is concerned with the theoretical design and investigation of a new system for optical pumping of solid state lasers. The originality of the new system lies in the use of optical fibres to transmit the light from its source to the laser-active material, thus allowing complete spatial separation of the two. The degree of uniformity achieved in illuminating the surface of the laser material is theoretically investigated and is shown to be very high. The efficiency of the system is also examined and the resulting advantages and disadvantages are pointed out. The possibilities for the realization of such a system are discussed and various ways of construction are proposed.     

Giant Electro‐Optical Effect through Electrostriction in a Nanomechanical Metamaterial

Electrostriction is a property of all naturally occurring dielectrics whereby they are mechanically deformed under the application of an electric field. It is demonstrated here that an artificial metamaterial nanostructure comprising arrays of dielectric nanowires, made of silicon and indium tin oxide, is reversibly structurally deformed under the application of an electric field, and that this reconfiguration is accompanied by substantial changes in optical transmission and reflection, thus providing a strong electro‐optic effect. Such metamaterials can be used as the functional elements of electro‐optic modulators in the visible to near‐infrared part of the spectrum. A modulator operating at 1550 nm with effective electrostriction and electro‐optic coefficients of order 10^?13 m² V^?2 and 10^?6 m V^?1, respectively, is demonstrated. Transmission changes of up to 3.5% are obtained with a 500 mV control signal at a modulation frequency of ≈6.5 MHz. With a resonant optical response that can be spectrally tuned by design, modulators based on the artificial electrostrictive effect may be used for laser Q‐switching and mode‐locking among other applications that require modulation at megahertz frequencies.     

Effective Excitation of Magnetoelectric Voltage Harmonics in a Ferromagnet–Piezoelectric Structure by Current Passing through the Magnetic Layer

Technical Physics Letters - The magnetoelectric (ME) effect in a planar amorphous ferromagnet–piezoelectric lead zirconate titanate (PZT) composite structure can be effectively excited by...     

一种高制动效率大角度硅扭转微镜MEMS光开关的设计

提出了一种利用静电力制动扭转梁带动微镜旋转,从而实现二维开关功能的MEMS光开关.使用ANSYS和COVENTOR软件对器件结构进行了模态、静态和瞬态分析,并对微镜制动梳齿的位置、器件的尺寸和扭转梁结构进行了优化.通过在微镜下方设计大空腔实现微镜90°的大角度扭转,使用新型衬底梳齿和结合扭转梁设计实现高静电制动效率,将制动电压降至18V.引入背面梳齿提高开关响应速度,模拟结果表明,光开关具有毫秒量级响应时间.与其他设计相比,该设计的微镜具有扭转角度大、制动效率高且开关速度较快的优点.     

A Solution‐Processed Ultrafast Optical Switch Based on a Nanostructured Epsilon‐Near‐Zero Medium

All the optical properties of materials are derived from dielectric function. In spectral region where the dielectric permittivity approaches zero, known as epsilon‐near‐zero (ENZ) region, the propagating light within the material attains a very high phase velocity, and meanwhile the material exhibits strong optical nonlinearity. The interplay between the linear and nonlinear optical response in these materials thus offers unprecedented pathways for all‐optical control and device design. Here the authors demonstrate ultrafast all‐optical modulation based on a typical ENZ material of indium tin oxide (ITO) nanocrystals (NCs), accessed by a wet‐chemistry route. In the ENZ region, the authors find that the optical response in these ITO NCs is associated with a strong nonlinear character, exhibiting sub‐picosecond response time (corresponding to frequencies over 2 THz) and modulation depth up to ≈160%. This large optical nonlinearity benefits from the highly confined geometry in addition to the ENZ enhancement effect of the ITO NCs. Based on these ENZ NCs, the authors successfully demonstrate a fiber optical switch that allows switching of continuous laser wave into femtosecond laser pulses. Combined with facile processibility and tunable optical properties, these solution‐processed ENZ NCs may offer a scalable and printable material solution for dynamic photonic and optoelectronic devices.     

Optical imaging through turbid media with a degenerate four wave mixing correlation time gate

A novel method for detection of ballistic light and rejection of unwanted diffusive light to image structures inside highly scattering media is demonstrated. Degenerate four wave mixing (DFWM) of a doubled YAG laser in Rhodamine 6G is used to provide an ultrafast correlation time gate to discriminate against light that has undergone multiple scattering and therefore lost memory of the structures inside the scattering medium. We present preliminary results that determine the nature of the DFWM grating, confirm the coherence time of the laser, prove the phase-conjugate nature of the signal beam, and determine the dependence of the signal (reflectivity) on dye concentration and laser intensity. Finally, we have obtained images of a test cross-hair pattern through highly turbid suspensions of whole milk in water that are opaque to the naked eye. These imaging experiments demonstrate the utility of DFWM for imagingthrough turbid media. Based on our results, the use of DFWM as an ultrafast time gate for the detectionof ballistic light in optical mammography appears to hold great promise for improving the current state of the art.     

Development of a 7 T Experiment System for Superconducting Switch Test

A 7 T experiment system, which was designed for a MRI superconducting switch test, has been developed at the Institute of High Energy Physics (IHEP) of China. The system mainly consists of a 7 T background superconducting coil, two pairs of 800 A vapor cooled current leads, a data acquisition system and more. The NbTi superconducting coil, with an operating current of 376 A, has a central field of 7 T and clear bore of 80 mm. The no-impregnation technique was adopted to fabricate this coil. The coil reached 96% of its short sample performance after three times quench. The system detailed experiments are presented in this paper.     

浸没发热球体冷冻水绕流作用下水体温度稳定性分析

本文通过推导在冷冻水绕流发热球体传热过程中,水池内水体平均温度随时间的变化公式,研究冷冻水理论降温所需最小流量、水体稳定温度和所需稳定时间的主要影响因素,分析水池内所容纳水体质量及初始温度、冷冻水流量及温度等参数对水体温度稳定性的影响。根据某工程实际情况确定冷冻水温度、流量等参数,运用理论推导公式和CFD模拟技术计算水体温度稳定性。结果表明:当冷冻水温度为17℃时,理论最小质量流量为83. 7 t/h。经过6～7个月后水体温度将达到稳定,稳定温度为22. 4℃。     

Optical Character Generation for a High-Speed Non-Impact Printer

The requirements for optical character generation for a commercial electrophotographic high-speed printer—more than 10,000 1pm—are given. They lead to the conclusion that the principal elements of a character generator will he a laser, an acousto-optic deflector and a polygon mirror.

The arrangement of a character generator which has been realized in a commercial printer is described in detail. Its performance characteristics are calculated and compared to experimental results.     

Optical wavelet processor for a complex signal treatment

The expediency of creating optical wavelet processors capable of treating complex (in particular, noiselike) signals is justified. The results of treating phase-modulated signals with the aid of an optical wavelet processors are presented, which confirm the possibility of a real-time registration of the signal inhomogeneity.