掺杂染料的向列相液晶微粒材料的非线性光学研究

对布满液晶微粒的聚合物(PDLC)进行了简并四波混频及光学双稳态的研究,并在文中对相关的PDLC中的分子重取向和热效应的非线性光学效应进行了讨论.     

Optical current transducer with bulk type Bi12SiO20 faraday sensor for power systems

Two types of optical current transducers (OCTs) have a bulk Faraday sensor inserted into the gap of an iron core and a porcelain insulator with optical fiber. The sensor consists of Bi₁₂SiO₂₀ (BSO) single crystal, a polarizer, and an analyzer. The OCTs satisfied the target performance requirement for fault location and metering and demonstrated maintained performance at some power utilities in Japan and the US. We have developed a fault location system that immediately detects the fault current with the OCTs, there by locating the fault section. The OCT can easily replace the existing support insulators for the disconnecting switch without any modifications to structure height or bus-bar. For metering requiring 0.3% class accuracy, use of a BSO with right optical rotatory power combined with BSO with left optical rotatory power results in a Faraday sensor with improved temperature characteristics. The OCT demonstrated 0.3% class accuracy for metering described in the current transformer Specifications of IEEE C57–13, 1993.     

光纤液位传感器检测原理探讨

叙述光纤液位传感器在贮油罐中的应用,提出实验所采用的方案。推导出液面高度公式,比较实现检测的两种电路的优缺点,同时对实验精度和测量范围进行了讨论。     

用频域法实现圆环形目标物的计数

研究了用频域法实现圆环形目标物计数的方法。对空域中含有圆环形目标物的二值图像，经傅里叶变换后在频域内进行滤波，再经傅里叶反变换后取一阈值进行处理，则对应于圆环形目标物即变为一个实心体，然后对实心体进行计数即可实现对圆环形目标物的计数。对该方法进行了数学描述，并分别用模拟图像和实际图像进行了实验。结果表明，该方法消除噪声的效果好，对部分封闭圆的检测同样有效，且可用于目标物有粘连的情况。该方法对圆环形目标物的尺寸相差不大的情况更为有效。     

Synthesis and optoelectronic properties of silole‐containing polyfluorenes with binary structures

2,5‐Bis(2‐bromofluorene‐7‐yl)silole was prepared by a modified one‐pot synthesis with a reverse addition procedure, from which novel silole‐containing polyfluorenes with binary random and alternating structures (silole contents between 4.5 and 25% and high M_w up to 509 kDa were successfully synthesized. The well‐defined repeating unit of the alternating copolymer comprises a terfluorene and a silole ring. Optoelectronic properties including UV absorption, electrochemistry, photoluminescence (PL), and electroluminescence (EL) of the copolymers were examined. The different excitation energy transfers from fluorene to silole of the copolymers in solution and in the solid state were compared. The films of the copolymers showed silole‐dominant green emissions with high absolute PL quantum yields up to 83%. EL devices of the copolymers with a configuration of ITO/PEDOT/copolymer/Ba/Al displayed exclusive silole emissions peaked at around 543 nm and the highest EL efficiency was achieved with the alternating copolymer. Using the alternating copolymer and poly(9,9‐dioctylfluorene) as the blend‐type emissive layer, a maximum external quantum efficiency of 1.99% (four times to that of the neat film) was realized, which was a high efficiency so far reported for silole‐containing polymers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 756–767, 2007     

光外差系统噪声等效功率的一种测量方法

本文介绍了利用工作于Bragg衍射的Ge晶体声光调制器作为外差系统中的频移器来测量外差系统的噪声等效功率(NEP)的方法。该方法具有测试系统简单、信号光功率、偏频可调的优点。实验测试与理论分析吻合。     

Optical bistability of planar metal/dielectric nonlinear nanostructures

We study theoretically a nonlinear response of the planar metal/dielectric nanostructures constituted from periodical array of ultra thin silver layers and the layers of Kerr-like nonlinear dielectric. We predict hysteresis-type dependences of the components of the tensor of effective dielectric permittivity on the field intensity allowing the change in material transmission properties from transparent to opaque and back at extremely low intensities of the light. It makes possible to control the light by light in all-optical nanoscale devices and circuits.     

CARS光谱测温及仪器狭缝函数对测量的影响

设计了一种利用光参量振荡器(OPO)来代替染料激光器的宽带相干反斯托克斯喇曼散射(CARS)光谱测温实验装置。为了提高CARS测量温度的精度,测量和分析了检测系统中狭缝函数对测量结果的影响,确定了狭缝函数的具体形式。将测量结果与热电偶读数比较,发现在温度范围300K～1200K内,温度测量的不确定度小于2%。     

掺铒光纤放大器中上转换过程的影响

掺杂浓度的提高影响了掺铒光纤放大器(EDFA)的性能,对经典Giles模型提出了新的要求。首先研究了高掺杂下铒离子距离较小引起的上转换过程的机理,通过优化速率方程模型分析了上转换过程对EDFA的影响,得出了在泵浦光和信号光远远大于ASE光的假设下泵浦光和信号光沿光纤长度变化的近似表达式,并将该近似分析解与解析解进行了比较。仿真结果表明上转换过程会降低随光纤传输的信号光和泵浦光,影响EDFA的放大性能,并得出了当掺铒浓度大于2.95×1025m-3时,上转换过程的影响不能忽略的结论。     

TDI线扫相机光学通道建模与仿真

卫星相机建模与仿真研究不论在民用还是军事领域都具有重要的理论研究和实际应用价值。根据TDI线扫相机的工作原理建立了一个TDI线扫相机光学通道的数学模型,该模型包括从景物到TDI CCD离散图像的几何投影关系和能量传递关系两部分,对于确定的成像系统,给定景物参数和光学系统参数,就可以确定对应图像传感器上的离散图像。为了验证模型,对一幅卫星图像进行了计算机仿真。建立的模型可以用来研究当成像条件改变时对图像的影响,进一步还可以用来发展虚拟卫星相机系统。