Ta2O5/SiO2硬膜双腔滤光片激光损伤特性研究

研究了Ta2O5／SiO2硬膜双腔干涉滤光片带内、带边及带外的吸收和激光损伤特性。实验发现，对于作用激光，带通滤光片的驻波场分布、吸收率和损伤阈值在带内、带边和带外的响应特性对作用激光波长均呈现出明显的选择性。根据实验结果，结合滤光片的驻波场分析，给出了带通滤光片的损伤机理。     

全固体腔内倍频Nd:YAG/SrWO4/KTP拉曼激光器

报道了以KTP晶体作为倍频介质,以Nd:YAG晶体作为激活介质,以SrWO4晶体作为拉曼介质的折叠腔型主动调Q腔内倍频拉曼激光器的输出特性,给出了输出黄光平均功率、脉冲能最、脉冲宽度随激光二极管(LD)抽运功率及脉冲重复率的变化关系.在输入抽运功率为12.6 W,脉冲重复率为20 kHz时,获得了1.4 W的590 nm激光输出,从LD到黄光的转换效率为11.1%.在输入抽运功率为12.6 W,脉冲重复率为10 kHz时,单脉冲能量为122 μJ,脉冲宽度为4.0 ns.相应的脉冲峰值功率为30.5 kW.     

激光淬火能量转换系数的ANSYS分析

基于有限元分析软件ANSYS对激光表面淬火温度场进行模拟,并结合实验的数据,建立了材料表面能量转换系数的变化规律的数学模型。通过再次实验验证表明,可用于预测激光表面淬火后的硬化层深并具有极高的精确性,为研究精确控制工艺参数和相变硬化层深提供新的研究思路。     

Inverse halftoning and kernel estimation for error diffusion

Two different approaches in the inverse halftoning of error-diffused images are considered. The first approach uses linear filtering and statistical smoothing that reconstructs a gray-scale image from a given error-diffused image. The second approach can be viewed as a projection operation, where one assumes the error diffusion kernel is known, and finds a gray-scale image that will be halftoned into the same binary image. Two projection algorithms, viz., minimum mean square error (MMSE) projection and maximum a posteriori probability (MAP) projection, that differ on the way an inverse quantization step is performed, are developed. Among the filtering and the two projection algorithms, MAP projection provides the best performance for inverse halftoning. Using techniques from adaptive signal processing, we suggest a method for estimating the error diffusion kernel from the given halftone. This means that the projection algorithms can be applied in the inverse halftoning of any error-diffused image without requiring any a priori information on the error diffusion kernel. It is shown that the kernel estimation algorithm combined with MAP projection provide the same performance in inverse halftoning compared to the case where the error diffusion kernel is known.     

光纤光参量放大增益特性的研究

分析了光纤光参量放大过程泵浦光与信号光的非线性相互作用，得到信号光增益G_s。进一步分析G_s，获得其增益带宽特性，只有在泵浦波长大于光纤零色散波长时才有增益，带宽约为50nm。     

Domain Engineering in ReS2 by Coupling Strain during Electrochemical Exfoliation

Chemical exfoliation has been used for the fast and large‐scale production of 2D nanosheets from graphene and transition metal dichalcogenides; however, it is rarely used for domain engineering of exfoliated nanosheets. Herein, it is found that the use of large sized molecular intercalants during electrochemical intercalation induce atomic row dislocation and parallel mirror twin boundaries (MTBs) on an otherwise pristine rhenium disulfide (ReS₂) crystal, such that the exfoliated flakes possess a parallel, multi‐domain structure. These domains can be distinguished under a polarized microscope owing to the intrinsic in‐plane optical dichroic properties of ReS₂, thereby affording a way to track the number of domains introduced versus the size of the molecular intercalant during electrochemical exfoliation. Ferromagnetism is detected on the intercalated sample using large sized molecular intercalants. Density function theory suggests that these may be due to the coupled effects of lattice strain and S vacancies in the MTBs.     

一种新的PCC-OFDM盲时偏估计算法

提出了一种新的PCC-OFDM盲时偏估计算法,首先使时域信号包络与窗函数循环卷积,进行时偏快速粗估计,然后利用解调信号方差进行判决,获得精确的时偏估计.该算法不需要训练序列、导频信号或循环前缀.仿真结果证明,该算法估计精度高于已有的PCC-OFDM盲时偏估计算法.     

基于.NET的网络微型图书借阅管理系统用户需求分析

随着社会的发展，图书的种类不断增加，图书馆的馆藏越来越多，管理也越来越复杂。图书借阅管理系统改善了原有的图书借阅中的手工图书卡管理方法，使原本复杂的图书馆的管理工作变得简单起来。     

负色散镜的设计、制备及在掺钛蓝宝石激光谐振腔内的使用

根据钛宝石激光器的要求设计了性能优良的两种负色散镜(NDM1和NDM2)。NDM1同时引入啁啾效应和G-T效应产生大的群延迟色散量以减少光在负色散镜上的反射次数。NDM2仅引入G-T效应产生较小的群延迟色散以补偿腔内自相位调制带来的部分啁啾。选用离子束溅射法制备了这两种负色散镜。用分光光度计测试了它们的透射率。结果表明,所制备的负色散镜的性能与设计性能非常接近。使用这两种负色散镜进行掺钛蓝宝石激光谐振腔内色散补偿实现了飞秒脉冲锁模,获得了15 fs的超短脉冲。     

双闪耀光栅的计算机设计与制作方法

提出一种用计算机设计制作的双闪耀光栅，是在闪耀光栅和双频光栅基础上发展起来的一种新型光学元件，是由微闪耀光栅列阵组成的、兼有闪耀光栅和双频光栅的优良特性。