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基于信号子空间的激光主动成像散斑去除
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作者 王灿进 孙涛 +2 位作者 王挺峰 郭劲 刘玉龙 《吉林大学学报(工学版)》 EI CAS CSCD 北大核心 2015年第4期1347-1352,共6页
为研究激光主动成像中散斑噪声的抑制问题,提出一种基于信号子空间TDC(Timedomain constrained)的散斑去噪方法,并搭建一套基于距离选通ICCD的激光主动照明系统进行实验验证。首先使用同态变换将乘性噪声变为加性噪声,然后利用小波变换... 为研究激光主动成像中散斑噪声的抑制问题,提出一种基于信号子空间TDC(Timedomain constrained)的散斑去噪方法,并搭建一套基于距离选通ICCD的激光主动照明系统进行实验验证。首先使用同态变换将乘性噪声变为加性噪声,然后利用小波变换估计噪声的协方差;接着对含噪图像进行奇异值分解并估计信号子空间的维数,根据该维数对无噪图像的协方差矩阵进行特征值分解,计算出滤波估计矩阵。将滤波估计矩阵与含噪图像卷积,最后做同态逆变换,得到降噪后的图像。结果证明本文的去噪方法拥有比经典的Lee、Frost和Kuan算法更好的散斑噪声抑制效果,同时计算时间明显缩短。 展开更多
关键词 信息处理技术 激光主动成像 信号子空间 散斑噪声 时域限制 同态变换
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Formation mechanism and modulation of electromagnetically induced transparency-like transmission in side-coupled structures 被引量:2
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作者 杨辉 李宏建 +3 位作者 许秀科 何智慧 王云 徐国均 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第6期2020-2026,共7页
Based on Fabry model and finite-different time-domain(FDTD) method, the plasmonic structure composed of a metal-insulator-metal(MIM) bus waveguide and a side-coupled resonator was investigated. It is found that the tr... Based on Fabry model and finite-different time-domain(FDTD) method, the plasmonic structure composed of a metal-insulator-metal(MIM) bus waveguide and a side-coupled resonator was investigated. It is found that the transmission features can be regulated by the cavity width and coupling distance. Electromagnetically induced transparency(EIT)-like transmission can be excited by adding an identical resonator on the pre-existing structure. Combining the foregoing theoretical analysis with coupled mode theory(CMT), the formation process of the EIT-like transmission was detailedly analyzed. EIT-like transmission can also be excited in plasmonic structure with two detuned resonators. By altering the structure parameters, the transparency window can be purposefully modulated. With the merits of compact structure and simplicity in fabrication, the proposed structures may have a broad prospect of applications in highly integrated optical circuits. 展开更多
关键词 metal-insulator-metal (MIM) waveguide side-coupled resonator electromagnetically induced transpareucy (EIT)-like transmission formation mechanism
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Novel sol-gel material for fabrication of a long period waveguide grating filter as a precise thermometer 被引量:2
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作者 WANG Xin LI XiaoChan +10 位作者 ZHANG Tao HU CanDong ZHU QiuXiang CHEN SiHai LI Yun XU Jia HE Miao NIU QiaoLi ZHAO LingZhi LI ShuTi ZHANG Yong 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2011年第11期1967-1971,共5页
A new kind of organic-inorganic hybrid HfO2/SiO2 sol-gel material with a large thermo-optic coefficient and a wide linear tunable temperature range has been developed for fabrication of a long period waveguide grating... A new kind of organic-inorganic hybrid HfO2/SiO2 sol-gel material with a large thermo-optic coefficient and a wide linear tunable temperature range has been developed for fabrication of a long period waveguide grating (LPWG) filter, whose parameters were optimized and designed by using finite difference time domain (FDTD) simulations. The LPWG filter, a periodic rectangle-corrugated grating structure, was easily fabricated with soft-lithography technique. At a temperature range from 19~C to 70~C, the fabricated LPWG filter element demonstrated a high temperature sensitivity of about 6.5 nm/~C and a wide linear tunable temperature range of 51℃, so that it can be used as a precise thermometer. Our results are useful for the designs of LPWG filters for the implementation of a wide range of thermo-optic functions. 展开更多
关键词 LPWG filter SOFT-LITHOGRAPHY sol-gel material temperature sensitivity
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Reflective terahertz tunable polarization controller 被引量:2
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作者 牛超 常胜江 《Optoelectronics Letters》 EI 2012年第4期264-268,共5页
This paper proposes an optical device which can continuously change the polarization state of terahertz (THz) waves. The device consists of metal gate, anU-refleetlon coatings, liquid crystal and mirror. By changing... This paper proposes an optical device which can continuously change the polarization state of terahertz (THz) waves. The device consists of metal gate, anU-refleetlon coatings, liquid crystal and mirror. By changing the refractive index of liquid crystal in the interface between the metal gate and the mirror, the phase difference between two beams with orthogonal polarization is varied and a continuous phase sliift is achieved. The phase shift of the device is calculated by using the finite difference time domain (FDTD) method, and the transmittance and reflectance are calculated by using the rigorous coupled wave analysis (RCWA) method. The results reveal that the structure can realize continuously tunable phase shift for THz wave at 1 THz. 展开更多
关键词 Finite difference time domain method Liquid crystals Mirrors Phase shift Phase shifters POLARIZATION Refractive index
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Fabricating scheme and optical properties of a flexible semiconductor micro-laser
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作者 王慧琴 欧阳红 +1 位作者 韩道福 王一凡 《Optoelectronics Letters》 EI 2011年第3期178-181,共4页
A new scheme for fabricating a kind of flexible semiconductor micro-laser is put forward.And the optical properties of this kind of flexible semiconductor laser are investigated by the finite difference time domain(FD... A new scheme for fabricating a kind of flexible semiconductor micro-laser is put forward.And the optical properties of this kind of flexible semiconductor laser are investigated by the finite difference time domain(FDTD) method.The results show that the light should be localized by photonic crystals(PCs),and the interaction between light and gain medium should be enhanced,while the mode of laser should be modulated.These results indicate that the PCs could control the spontaneous emission,and lead the radiation emission to the needed frequency. 展开更多
关键词 Finite difference time domain method LASERS Optical properties Photonic crystals Time domain analysis
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