Study on Dual Bragg Wavelength Fiber Grating and Its Tuning Scheme

Because of package, a single FBG has dual Bragg wavelength. One is sensitive to stress and the other is sensitive to temperature. By using the special mechanism, the wavelengths can be tuned by stress and temperature respectively.     

用反射法自动测量大尺寸样品的折射率分布

针对大尺寸样品的折射率分布测量,引入自动扫描装置和适时数据处理系统,研究出一种高灵敏度的智能化反射法折射率分布测量仪,可进行快速、自动、准确的折射率分布测量.经理论分析和实验研究提出了一套合理的实验数据处理方法.并具体介绍和详尽分析了实验装置,讨论了有关理论和实验误差,给出了消除各种误差的有效方法,最终得出较为理想的实验结果.     

Repetition rate multipliers for efficient implementation of multiphoton and pump-probe fluorescence microscopy

With the advances in pulsed laser systems, microscopic imaging techniques such as multiphoton and pump-probe fluorescence microscopy have developed into effective tools for investigating intensity and time-resolved phenomena inside biological systems. However, pulsed lasers used in these techniques usually are commercial systems with repetition frequencies of around 80 MHz. While these systems have proven to be adequate for multiphoton and pump-probe microscopic imaging applications, the temporal separation of the laser pulse train (around 12.5 ns) is long compared to the fluorescence lifetimes of many common fluorescence species. In this work, we present the designs of repetition rate multipliers based on passive optical components that can be used to increase the efficiency in multiphoton and pump-probe fluorescence microscopy. Depending on the lifetime of fluorescence molecules under investigation, the passive repetition rate multiplier can increase the duty cycle of multiphoton or pump-probe microscopy up to fourfold.     

Investigation on nonradiative decay of I13/2→I15/2 transition of Er-doped oxide glasses

Nonradiative decay of ⁴I_13/2→⁴I_15/2 transition of Er³⁺ has been investigated in a series of oxide glasses. For Er³⁺-doped glass samples, the Judd-Ofelt analysis on absorption spectra was performed and the fluorescence lifetime was determined by extrapolating to zero Er³⁺ concentration limit. Infrared spectra were measured in order to investigate the influence of OH⁻ groups in different glasses. The effects of glass matrix on the decay rate were discussed from the viewpoint of phonon energy, variations of effective fields, and OH⁻ groups. Compared to other glasses, phosphate glass presents low quantum efficiency and large nonradiative decay rate due to its high phonon energy and hygroscopic behavior.     

The solvability conditions for inverse eigenproblem of symmetric and anti‐persymmetric matrices and its approximation

The problem of generating a matrix A with specified eigen‐pair, where A is a symmetric and anti‐persymmetric matrix, is presented. An existence theorem is given and proved. A general expression of such a matrix is provided. We denote the set of such matrices by ??????_Eⁿ. The optimal approximation problem associated with ??????_Eⁿ is discussed, that is: to find the nearest matrix to a given matrix A* by A∈??????_Eⁿ. The existence and uniqueness of the optimal approximation problem is proved and the expression is provided for this nearest matrix. Copyright © 2002 John Wiley & Sons, Ltd.     

Characteristics and structures of weak efficient surfaces of production possibility sets

This paper studies the characteristics and structure of the weak surface of the production possibility set. We apply techniques and methods of transferring a polyhedral cone from its intersection form to its sum form, identify an intersection representation of the production possibility set. We give the structure theorem of weak surface of the production possibility set, which includes three complementary slackness conditions. We define the input weak efficiency and output weak efficiency for different DEA models according to the representation of the intersection form. It investigates the characteristics of the weak surfaces, and proves the structure theorems of input weak DEA efficiency and output weak DEA efficiency. The structure theorems establish weighted combination of inputs and outputs that are weak DEA efficient. Numerical examples are provided for illustration.     

关于NF-环的构造

研究了无限的ＮＦ－环及有限的ＮＦ－环，并且给出了有限ＮＦ－环的构造．     

A trace class operator inequality

In this note, we generalize the inequality about the trace of positive semidefinite matrix trk(AB)?k(trA)k(trB) to Hilbert space, and obtain a relevant inequality about positive trace class operator.     

迭代的计算与估计

对高次多项式函数这类非线性映射给出了一般 n次迭代的一个计算结果 ,还讨论了一维欧氏空间中一些非多项式型映射的迭代 .在二维欧氏空间中 ,我们给出了几类特殊的非线性迭代的结果 .对于一些难以精确计算迭代表达式的映射 ,我们给出了其迭代的估计 .