Author Affiliations
Abstract
1 Department of Photoelectric Measurement and Control, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
2 University of Chinese Academy of Sciences, Beijing 100049, China
A novel no-reference (NR) image quality assessment (IQA) method is proposed for assessing image quality across multifarious distortion categories. The new method transforms distorted images into the shearlet domain using a non-subsample shearlet transform (NSST), and designs the image quality feature vector to describe images utilizing natural scenes statistical features: coefficient distribution, energy distribution and structural correlation (SC) across orientations and scales. The final image quality is achieved from distortion classification and regression models trained by a support vector machine (SVM). The experimental results on the LIVE2 IQA database indicate that the method can assess image quality effectively, and the extracted features are susceptive to the category and severity of distortion. Furthermore, our proposed method is database independent and has a higher correlation rate and lower root mean squared error (RMSE) with human perception than other high performance NR IQA methods.
光电子快报（英文版）
2016, 12(2): 152
中北大学 信息与通信工程学院 山西省光电信息与仪器工程技术研究中心, 太原 030051
为了改善纳米纤芯光纤的非线性与色散特性, 提出利用气孔填充非线性液体的新型纳米纤芯光纤结构来增强现有纳米纤芯光纤的非线性系数, 利用选择性填充方法来改进现有纳米纤芯光纤的特性调控能力, 实现改善光纤非线性和色散特性目的.分析结果表明采用选择性气孔填充方式和适当的光纤参量有助于实现光纤单模单偏振工作,可以大幅度地提升纳米纤芯光纤的非线性系数和改善光纤色散特性.
光纤 非线性仿真 色散 铋基 光纤模式 Fiber Nonlinearity simulation Dispersion Bismuth Fiber models
Author Affiliations
Abstract
1 Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Shanghai University, Shanghai 200072, China
2 College of Information Science and Technology, Donghua University, Shanghai 201620, China
3 School of Electronic and Information Engineering, Beihang University, Beijing 100191, China
An all-optical transient waveform equivalent time sampling system based on cross-gain modulation (XGM) in semiconductor optical amplifier (SOA) is presented. A noisy SOA dynamic model and PIN equivalent circuit function are employed for system evaluating. The results show this SOA-XGM sampler with subtracting postprocessing can achieve picosecond sampling window. The shape of sampling window can be adjusted by SOA bias current and amplitude of control pulse. Compared with amplified spontaneous emission (ASE) noise of SOA and thermal noise in PIN, the jitter of sampling control pulse causes most sampling error. Simulations show that this SOA-XGM sampler can be a capable candidate for transient waveform sampling.
1 中国科学技术大学 国家同步辐射实验室，安徽 合肥 230029
2 中国科学技术大学 精密机械与精密仪器系，安徽 合肥 230027
为了抑制同步辐射光通过光栅单色器后出射的单色光在长波段的高次谐波以及提高光源在该波段的偏振特性，计算分析了三镜偏振器Au_Si_Au的偏振特性及其对长波段高次谐波的抑制效果。比较了Au_Si_Au，Au_SiC_Au和Au_Be_Au 3种不同材料的偏振镜抑制高次谐波的能力和对偏振度的提高。计算分析表明，Au_Si_Au三镜组合镜对长波段的高次谐波抑制效果较好，光源通过Au_Si_Au三镜反射后，P分量的反射率几乎为0，而S分量在30 eV以后几乎全被抑制。Au_Si_Au三反射镜不仅可以抑制30 eV以上的高次谐波，而且使该波段光源的偏振性得到提高，20 eV时最高偏振度可达99%以上，从而在极大地改善同步辐射光源纯度的同时提高了光源的偏振度。
光源偏振 高次谐波抑制 三镜偏振器 polarization suppressing higher order harmonics triple-reflector polarizer 光学 精密工程
2011, 19(10): 2314
电子科技大学物理电子学院,四川,成都,610054
对于矩形栅这一经典的慢波结构,采用场匹配法来分析其慢波特性,进而得到其耦合阻抗.其中对槽区内的场处理,保留其高次项,表示为一无限本征驻波之和的形式.然后通过数值实例具体分析了矩形栅的两种典型结构:浅槽栅和深槽栅.当增大槽深后,色散增强,系统通带变窄,同时耦合阻抗有明显增大,工作点移向前向波区,适合用在放大器的慢波结构上.
矩形栅 色散关系 耦合阻抗 慢波系统 Rectangular waveguide grating Dispersion relation Coupling impedance Slow-wave system
