Author Affiliations
Abstract
1 State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China
2 College of Optical Sciences, University of Arizona, Tucson, Arizona 85721, USA
3 Department of Biomedical Engineering, University of Arizona, Tucson, Arizona 85721, USA
4 e-mail: judy@optics.arizona.edu
5 e-mail: euanmc@optics.arizona.edu
Ultra-high quality () whispering gallery mode (WGM) microtoroid optical resonators have demonstrated highly sensitive biomolecular detection down to the single molecule limit; however, the lack of a robust coupling method has prevented their widespread adoption outside the laboratory. We demonstrate through simulation that a phased array of nanorods can enable free-space coupling of light both into and out of a microtoroid while maintaining a high . To simulate large nanostructured WGM resonators, we developed a new approach known as FloWBEM, which is an efficient and compact 3D wedge model with custom boundary conditions that accurately simulate the resonant Fano interference between the traveling WGM waves and a nanorod array. Depending on the excitation conditions, we find loaded factors of the driven system as high as and signal-to-background ratios as high as 3.86%, greater than the noise levels of many commercial detectors. These results can drive future experimental implementation.
Photonics Research
2019, 7(9): 09000967
郑州大学 信息工程学院和数字化影像技术研究中心, 河南 郑州 450001
提出了一种基于剪切波的医学图像感兴趣区域(ROI)近无损压缩算法, 用于解决因小波对高维数据表示的局限性使其重构图像与原图像平均结构相似度(MSSIM)较低的问题。首先, 指定感兴趣区域并把其余部分视为背景区域(BG); 对两个区域分别进行剪切波变换, 并选取出能够近似逼近原区域的重要系数进行去噪和初步压缩。然后, 对ROI区域所选取的重要系数进行无损Huffman编码, 对BG区域所选取的重要系数量化并进行Huffman编码实现压缩。最后, 通过Huffman解码和剪切波逆变换实现解压从而获得重构图像。实验结果表明, 与改进多级树集合分裂算法(SPIHT)相比, 在相同压缩比下, 提出的算法所获取的ROI重构图像与原图像ROI的MSSIM提高了4%, 峰值信噪比 (PSNR)是改进SPIHT算法的2.35倍; 而整幅重构图像与原图像的MSSIM提高了3%, PSNR提高了28%。该算法可实现ROI 和BG 的相对质量可调, 适用于图像存档和通信系统(PACS)中的医学图像压缩。
医学图像 图像压缩 感兴趣区域 剪切波变换 Huffman编码 图像存档和通信系统 medical image image compression Region of Interest(ROI) shearlet transform Huffman coding Picture Archiving and Communication System(PACS)
1 北京邮电大学 理学院,北京 100876
2 北京邮电大学 光通信与光波技术教育部重点实验室,北京 100876
利用单边边界条件下的差分法求解非线性光纤光栅耦合模方程,在此基础上分析了光纤光栅中克尔非线性效应对光栅频谱特性的影响,分别讨论了短脉冲在均匀和切趾光纤光栅的线性工作区和非线性工作区的传输特性。结果表明,在合适的条件下,光纤布喇格光栅可以用于光开关器件。
光纤布喇格光栅 非线性耦合模方程 差分法 非线性效应 fiber Bragg grating(FBG) nonlinear coupled mode equation finite difference nonlinear effect
School of Sciences, Beijing University of Posts and Telecommunications, Beijing 100876, CHN
Fiber Bragg grating Filter Flat-top and steep-edge 半导体光子学与技术
2004, 10(4): 225
School of Sciences, Beijing University of Posts and Telecommunications, Beijing 100876, CHN
Polarization mode dispersion Tuning Super magnetostriction Differential group delays 半导体光子学与技术
2004, 10(3): 145
School of Sciences, Beijing University of Posts and Telecommunications, Beijing 100876, CHN
Fiber Bragg grating Nonlinear Super magnetostriction