The Baikal neutrino telescope—Results and plans

The Neutrino Telescope NT200 is operated since 1998 and was upgraded to the 10 Mton detector NT200+ in 2005. The preparation towards a km³-scale (Gigaton Volume) detector in Lake Baikal is currently a central activity. As an important milestone, a km³-prototype string, based on completely new technology, has been installed and was operating together with NT200+ since April 2008. Also selected astroparticle physics results from the long-term operation of NT200 are presented.     

溶剂法制备聚合物分散液晶膜

用溶剂法制备了聚合物分散液晶膜。采用偏光显微镜、扫描电子显微镜和电光仪对相分离和聚合物分散液晶材料的电光性能作了初步探讨。研究结果表明，升温速度和聚合物含量对PDLC膜的相分离结构和响应电压有显著的影响。     

全光通信网络节点功能结构研究

密集波分复用（DWDM）技术在提高传输能力的同时，还具有无可比拟的联网优势，使用光滤波器件或光开关就可构成重构性的具有联网功能的光分插复用器（OADM），OADM和DWDM技术的结合构成了最佳的全光城域网解决方案，本文描述了全光通信网络节点功能结构，研究了以光转发器OUT和OADM为基础的各种全光网节点结构。     

基于光纤光栅的波分复用系统设计

设计了两种基于光纤布拉格光栅的波分复用(WDM)系统,一种为基于光纤光栅的四路波分复用系统,另一种为结合光分插复用器(OADM)的四路波分复用系统。给出了基于Opti System的波分复用光传输系统仿真模型,对复用及解复用后的光信号进行仿真得出了光谱图,对传输性能及Q因子、误码率、眼图等参数进行分析。在第二种结构中光纤光栅作为色散补偿器、光反射器和滤波器使用,可以实现任一波长的上载和下路。两种波分复用系统眼图张开良好,误码率均低于10e-9。证明了波分复用系统的正确性和设计方案的可行性。     

A Multimode Fibre-coupled Compact Optical Wavelength Meter based on Wollaston Prisms

Abstract: We present a compact, portable, and mechanically robust instrument for measuring optical wavelength based on an arrangement of four Wollaston prisms that forms spatially localised fringes in a plane perpendicular to the optic axis. The wavelength is determined from the fringe period. After calibration, the instrument had an accuracy of c. 1 of 10⁶, and was immune to fluctuations in output intensity of a light source of up to 10 dB.     

Mach-Zehnder电光调制器产生多波长光源的实验研究

随着对光纤通信容量需求的不断增长,DWDM系统和L波段光器件成为当今研究的热点,多波长光源作为重要的有源器件倍受青睐。本文研究了基于Mach-Zehnder结构的电光强度调制器的理论模型,利用公式仿真得到在一定微波功率调制下强度调制器输出的扩频光谱。实验研究了M-Z结构的集成电光波导强度调制器光波长1550nm处10GHz、15GHz、20GHz扩频的实现,对理论分析所得的输出光谱与实际系统的输出光谱进行比较,发现谱线情况较一致。在调制频率10GHz,调制深度C=1.39,V=2.98V时,输出光谱中可清楚观察到正负三阶等频率间隔的边波带,尤其是一阶边波带与中心波长峰值功率几乎相等,可实现三路光源等功率输出。     

A Novel Multiple Component Gas Infrared Ray Sensor

1　IntroductionInfraredgasanalyzer(IGA)hasbeenwidelyappliedinseismforecast,minesecurity ,petroleumreconnaissance ,atmospherephysics,medicaltreatment,andpollutionsourcemonitoring,highvoltagefacilitydiagnostics ,chemicalin dustrysurveillanceandmetallurgyaswellasallnewtechnol ogyareasuchasbioscience ,micro electronicsandnewma terial.InthefutureIGAtechnicaltrendsaremultiplecom ponentgastestedsynchronously ,intelligentizedoperationandlowercost[1,2 ] .Atpresent,scholarsallworldhavedonemuchworktoan…     

Light concentrators for the Sudbury Neutrino Observatory

There is an important and growing class of elementary particle detectors which are characterized by a large sensitive volume (thousands of tonnes), very low radioactive backgrounds, and rely on the emission of light for particle detection. Water Cherenkov detectors come into this category; they have a large mass of water as the sensitive medium. Particles are detected when they interact with the water and produce Cherenkov light, so detection efficiency relies on having a huge light sensitive area at the periphery of the detector. The most cost-effective way of achieving this is by placing light concentrators on large photomultiplier tubes (PMTs). This paper describes the work carried out on light concentrators for the PMTs in the Sudbury Neutrino Observatory, a 1000 tonne heavy water Cherenkov detector. We discuss the advantages of using light concentrators, summarize the optical theory of non-imaging light concentration, and describe in detail the development and manufacture of the concentrators themselves.     

基于混沌正交组合序列的M元码分多址水声通信

提出了M元能量检测器算法,该算法简单易实现,极大优化了M元码分多址系统接收机结构和解码运算量。同时,M元能量检测器具有抗载波相位跳变和抗水声信道多途干扰的能力。针对M元码分多址水声通信系统中所需扩频序列数量庞大、选码难度高的问题,提出了混沌正交组合序列,通过简单的迭代组合即可产生大量满足要求的扩频序列,而且同族的混沌正交组合序列间满足正交关系。海试试验成功实现了7个用户的M元码分多址水声通信试验(M=512),共采用了3 584条混沌正交组合序列,每个用户通信速率为70 bit.s-1,验证了算法的有效性,为网络化水声通信的应用提供了技术基础。     

Shannon's theory in nonlinear systems

An exponential growth in the capacity of optical networks has taken place over the last decade, but the extent to which future capacity growth can continue is limited by physical laws governing signal propagation through optical fibres. While the classic theory of communication developed by Claude Shannon allows the analytical calculation of information spectral density limits for linear channels with white additive Gaussian noise, the nonlinear nature of optical fibres makes these limits much more difficult to determine for long-haul optical transmission. Accurately predicting the ultimate limits has been the focus of much recent research. This paper describes the sources of linear and nonlinear signal impairments, reviews progress on extending Shannon's theory to the case of nonlinear signal propagation, and discusses new optical and electronic signal processing techniques that may be used to approach the Shannon limit in future networks.