基于表面等离子体激元效应的可调制滤波器

针对常用的光学滤波器滤波波长不可变的特点,提出一种利用表面等离子体激元效应实现可调制滤波的方法.该方法根据金属邻近电介质的介电常数发生改变时,金属与入射光波的表面等离子体激元耦合共振模式发生改变,以此实现滤波波长调制.在加工有亚波长纳米孔阵列的Au薄膜上制作了一可见光滤波器,实验中采用空气、酒精和油作为介质对器件进行调制.结果表明:相对于常用的光学滤波器,该器件由于可以方便地改变临近介质的介电常数,因此具有滤波波长连续可调、快速方便、波长变化精度高等特点.     

基于可调高斯型滤波器的光纤光栅振动解调技术研究

 传统的匹配光纤布拉格光栅型光纤光栅波长解调系统具有波长匹配精度低、调节困难和动态测量范围小的缺点。为了克服上述缺点,采用波长可调谐高斯型滤波器代替传统匹配光纤光栅,提出了一种新型的光纤光栅波长解调技术。建立了基于高斯型滤波器的光纤光栅振动解调系统。对不同频率和振幅的周期性振动进行了解调实验。发现当选择合适带宽的滤波器时,透过滤波器的光功率随压电陶瓷上所加电压信号同步且高保真地变化,表明该系统对振动信号实现了有效的解调。该系统同时具有响应速度快、物理结构简单、动态测量范围大的优点。     

改进的live-wire交互式胸片图像分割

肺部轮廓提取是计算机辅助诊断(computer-aided detection,CAD)的关键之一,并且能为医生提供可靠的诊断数据。提出了一种交互式肺部分割方法,用优化的Gabor奇滤波器对胸片图像进行滤波得到边缘响应能量图,然后用此边缘响应能量值来构造Live-wire代价函数进行肺部分割。实验表明该算法能正确区分强弱边缘,快速有效地提取出肺部轮廓,与传统算法相比,能减少人机交互次数,更具鲁棒性和效率性的优点。     

基于高双折射光子晶体光纤环镜的全光纤平顶梳状滤波器(英文)

A novel all-fibre flat-top comb filter based on a high birefringence photonic crystal fibre loop mirror is proposed and demonstrated. We simulate theoretically its output spectra and experimentally realize a flat-top output with a high extinction ratio. Compared to filters consisting of the conventional Panda polarization maintaining fibre, filters based on a high birefringence photonic crystal fibre loop mirror have better temperature stability. This kind of filter can be expected to be used widely in Wave...     

All-fiber ring-cavity based frequency swept laser source for frequency domain OCT

<正>We develop a high-speed tunable,quasi-continuous-wave laser source for frequency domain(FD) optical coherence tomography(OCT).The laser resonance is realized within a unidirectional all-fiber ring cavity consisting of a fiber coupler,two fiber isolators,a semiconductor optical amplifier(SOA),and a fiber FabryPerot tunable filter(FFP-TF) for frequency tuning.Light output from the coupler is further amplified and spectral shaped by a booster SOA terminated at both ends with two isolators.The developed laser source provides up to 8000 sweeps per second over a full-width wavelength tuning range of 120 nm at center wavelength of 1320 nm with an average power of 9 mW,yielding an axial resolution of 13.6μm in air and a maximum sensitivity of about 112 dB for OCT imaging.The instantaneous linewidth is about 0.08 nm,enabling OCT imaging over an axial range of 3.4 mm in air.For optimization consideration based on this custom-built swept laser,experimental study on imaging quality relevant parameters of the swept laser with sine and ramp driving waveforms to the FFP-TF is conducted,and investigation of the swept laser on the cavity length is done.Implementing the laser source in our established swept source based OCT(SS-OCT) system,real-time structural imaging of biological tissue is demonstrated.     

Equal channel spacing Sagnac filter using high-birefringent photonic crystal fibers

An equal channel spacing Sagnac filter is proposed using a high-birefringent photonic crystal fiber （PCF） with birefringence square to the operation wavelength. A PCF with four smaller central air holes sur-rounded by larger air holes is applied in a Sagnac filter with optimized parameters to achieve equal channel spacing of 0.8 nm. Given that the birefringence of this PCF is square to the operation wavelength, the channel spacing of the proposed filter changes by only 0.03 nm within a wavelength range from 1400 to 1650 nm; this is about one order of magnitude less than that constructed with conventional high-birefringent fibers.     

具固定时刻的二阶脉冲微分系统零解的稳定性

利用脉冲微分不等式和分析技巧,构造Lyapunov函数给出了二阶具固定脉冲时刻的微分系统零解的稳定性的两个判定准则,特别突出了脉冲效应对系统稳定性的关键影响,并给出了其相关例子.     

融资互换的Nash谈判解

本尝试将Nash谈判解应用到金融领域中，从对策论的角度解释和探讨了互换的源泉、机制和定价模型，提出互换过程即为一个求解Nash谈判解的过程，在不考虑风险和考虑风险的情况下，分别求出谈判双方的收益比。     

装备采购费用估算在采购合同谈判中的应用

航天装备采购费用估算是航天装备采购管理工作的重要组成部分.采购合同谈判是航天装备采购工作的重要环节.本文研究在可靠性增长费用和供货方利润固定的情况下,如何确定采购费用的上限.该结果有利于航天装备采购部门在采购合同谈判时把握主动权,控制采购费用增长.     

AN EXISTENCE THEOREM OF POSITIVE SOLUTIONS FOR ELASTIC BEAM EQUATION WITH BOTH FIXED END-POINTS

Abstract. By using the degree theory on cone an existence theorem of positive solution for aclass of fourth-order two-point BVP‘s is obtained. This class of BVP‘s usually describes the de-formation of the elastic beam with both fixed end-points.