“慢”光理论及实验研究进展

近年来的研究表明,精确控制光脉冲在介质中的传播速度是完全可行的．利用电磁场与介质相互作用形成的电磁诱导透明,人们已在不同介质中实现了“超快”光和“慢”光效应的实验观测．其中,能使光脉冲的传播速度减慢甚至停滞的“慢”光效应,由于其在光信息存贮和光计算等领域的巨大潜在应用价值而引起了更多的关注,成为量子光学和非线性光学领域的研究热点．这里详细论述“慢”光形成的物理机制,并对相关理论及其实验研究过程进行分析．     

成人腕关节软骨盘形态学特征研究

腕关节是人体关节中活动多、运动幅度大的关节之一,其中参加构成该关节窝的软骨盘尤其容易发生急性损伤或慢性劳损,对此结构进行形态学特征的研究有助于了解其损伤的机制,并提出行之有效的防治方法,为此本研究进行了成人腕关节软骨盘形态学特征方面的工作,其结论是:1)软骨盘具有多种形状,主要为三角形、半月形、扇形;2)腕关节软骨盘内,以及软骨膜中均有丰富的血管分布,表明软骨盘的营养供应比较充分,有利于损伤的修复;3)腕关节软骨盘为典型的纤维软骨,各部位纤维排列有明显的不同,将有助于软骨盘所受力的传递、分散与缓冲,更好的发挥软骨盘的功能.     

浅谈医院信息建设的数据安全

文章从医院信息建设中的数据维护安全性分析、双机容错设备的选择和应用、备份及灾难恢复、科学管理工作流程等方面，探讨医院信息建设中数据安全维护与应用。     

新一代光网络

本文概要介绍了ASON在光传送网中引入控制平面以实现网络资源的按需分配,从而实现光网络智能化的全自动交换,使未来的光传送网能成为向任何地点和任何用户提供连接的网。     

基于AWG的光信号处理器的设计

在集成光波导器件阵列波导光栅的空间频域特性,即“分频成谱,合频成像”的频率特性基础上,运用频域综合法,在阵列波导光栅的频谱区引入不同的滤波函数,通过在阵列波导中部嵌入余弦振幅型光栅模片,设计出了光信号加减器;对中心阵列波导单元增加额外特定长度,从而引入π／2相位,设计出了相衬滤波器．     

克尔型光学格子中的光束传输

推导具有横向和纵向折射率周期性调制的克尔型非线性介质光学格子中的光束传输方程,通过数值模拟发现了一个有趣的现象：适当的调制周期使光束分裂成两束斜向传输的光束,并且调制周期过大或过小都不能产生这个现象．此现象对光学格子的研究有一定的参考价值．     

Novel Electro-Optical Modulator Utilizing GeO2-Doped Silica Waveguide

In order to achieve a modulator with broad bandwidth and perfect impedance match,a novel electro-optical modulator based on GeO2-doped silica waveguides on silicon substrate is designed.The finite element model of the whole electro-optical modulator is established by means of ANSYS.With the finite element method analysis,the performance of the novel modulator is predicted.The simulation reveals that the designed modulator operates with a product of 3 dB optical bandwidth and modulating length of 226.59 GHz-cm,and a characteristic impedance of 51.6 Ω at 1 550 nm wavelength.Moreover,the calculated electrical reflected power of coplanar waveguide electrode is below -20 dB in the frequency ranging from 45 MHz to 65 GHz.Therefore,the designed modulator has wide modulation bandwidth and perfect impedance match.     

Detecting and Tracking Moving Targets on Omnidirectional Vislon

A method was presented to implement the detecting and tracking of moving targets through omnidirectional vision.The method combined optical flow with particle filter arithmetic.in which optical flow field was used to detect and locate moving targets and particle filter was used to track the detected moving objects.According to the circular image character of omnidirectionaI vision.the calculation equation of optical flow field and the tracking arithmetic of particle filter were improved based on the polar coordinates at the omnidirectional center.The edge of a randomly moving object could be detected by optical flow field and was surrounded by a reference region in the particle filter.A dynamic motion model was established to predict particle state.Histograms were used as the features in the reference region and candidate regions.The mutual information(MI)and Gaussian function were combined to calculate particle weights.Finally,the state of tracked object was computed by the total particle states with weights.Experiment results show that the proposed method could detect and track moving objects with better realtime performance and accuracy.     

Femtosecond Optical Trapping of Cells： Efficiency and Viability

The femtosecond optical trapping capability and the effect of femtosecond laser pulses on cell viability were studied. The maximum lateral velocity at which the particles just failed to be trapped, together with the measured average trapping power, were used to calculate the lateral trapping force (Q-value). The viability of the cells after femtosecond laser trapping was ascertained by vital staining. Measurement of the Q-values shows that femtosecond optical tweezers are just as effective as continuous wave optical tweezers. The experiments demonstrate that there is a critical limit for exposure time at each corresponding laser power of femtosecond optical tweezers, and femtosecond laser tweezers are safe for optical trapping at low power with short exposure time.