光子学报
2022, 51(11): 1114005
1 中国科学院微小卫星创新研究院, 上海 201203
2 中国科学院大学, 北京 100049
星图识别算法是星敏感器中的关键技术,通过对观测恒星的识别实现对航天器的高精度姿态解算。现有的星图识别算法,通常需要选取最近的邻星作为起始星,从而过于依赖起始星的选取导致识别准确率不佳。因此,提出了一种基于动态夹角匹配的识别算法,使用邻星之间的夹角以及邻星与观测星之间的距离作为动态夹角特征,并借助该特征计算观测星与各个导航星之间的匹配度得分,最终将匹配度得分最高的导航星作为识别结果。仿真验证结果表明,该方法具有较高的识别率且对于噪声具有较强的鲁棒性。在对16200幅模拟星图的仿真实验中,该方法的识别率可达到99.80%,并在位置噪声、伪星以及星等噪声影响下均能保持97.00%以上的识别率。
模式识别 星敏感器 星图识别 动态夹角 匹配度 光学学报
2021, 41(16): 1610001
1 西南大学 物理科学与技术学院，重庆40075
2 西南大学 数学与统计学院，重庆400715
基于二极管泵浦Nd：LaMgAl11O19无序晶体激光器实现了被动调Q激光以及脉冲幅度混沌激光的输出。当泵浦功率在4.8 ~8.6 W范围内时，激光器运转在被动调Q状态；当泵浦功率为8.6 W时，调Q激光的平均输出功率为613 mW、重复频率为157.1 kHz、脉冲宽度为2.2 μs。当泵浦功率增加到8.7~10.5 W范围内时，输出激光的脉冲幅度呈不规则随机分布现象；通过分析脉冲峰值序列的自相关曲线、相位图、功率谱、随机直方图，判定激光器运转在脉冲幅度混沌状态；当泵浦功率功率为10.5 W时，脉冲幅度混沌激光的平均输出功率为814 mW。
Passively Q-switched Pulse amplitude chaos Nd：LaMgAl11O19 disorder crystal Diode-pumped All-solid-state laser 被动调Q 脉冲幅度混沌 Nd：LaMgAl11O19无序晶体 二极管泵浦 全固态激光器
华东交通大学光机电技术及应用研究所, 江西 南昌 330013
茶叶叶片叶绿素含量的准确监测对茶树的营养状况和生长态势具有重要意义,为此基于叶绿素荧光光谱技术提出一种快速无损检测叶片叶绿素含量的方法。利用叶绿素荧光采集装置对茶叶叶片进行光谱采集,并测量叶绿素相对含量。采用S-G(Savitzky-Golay)平滑法对光谱进行预处理,可以消除大量的噪声信号;对所提方法与传统方法进行比较。实验结果表明,采用所提方法能够有效消除无关变量,对模型的优化可以得到较好的效果;简化变量后所建立的偏最小二乘模型在预测集上的相关系数为0.96,方均根误差为0.87,在建模集上的相关系数为0.96,方均根误差为0.95;荧光光谱结合化学计量学方法可以为茶叶叶片叶绿素含量的定量分析提供一种快速简便的分析方法。
光谱学 荧光光谱 连续投影算法 后向区间偏最小二乘法 叶绿素 激光与光电子学进展
2021, 58(8): 0830001
Author Affiliations
Abstract
1 College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
2 Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China
3 College of Arts and Science, Shanghai Dianji University, Shanghai 201306, China
4 e-mail: chenr@sustech.edu.cn
5 e-mail: tche@szu.edu.cn
In this work, one kind of type II ZnSe/CdS/ZnS core/shell/shell nanocrystals (NCs) is synthesized, and their linear and nonlinear photophysical properties are investigated. Through measurements of the temperature-dependent photoluminescence spectra of NCs, their excitonic properties, including the coefficient of the bandgap change, coupling strength of the exciton acoustic phonons, exciton longitudinal optical (LO) phonons, and LO–phonon energy are revealed. Femtosecond transient absorption spectroscopy was employed to obtain insight into ultrafast processes occurring at the interface of ZnSe and CdS, such as those involving the injection of photo-induced electrons into the CdS shell, interfacial state bleaching, and charge separation time. At the end, their multiphoton absorption spectra were determined by using the z-scan technique, which yielded a maximum two-photon absorption cross section of 3717 GM at 820 nm and three-photon absorption cross section up to at 1220 nm, respectively. The photophysical properties presented here may be important for exploiting their relevant applications in optoelectronic devices and deep-tissue bioimaging.
Photonics Research
2020, 8(9): 09001416
华东交通大学光机电技术及应用研究所, 江西 南昌 330013
炭疽病是油茶最常见的病害之一,因此对油茶炭疽病进行快速检测具有重要意义。提出了一种检测油茶叶片炭疽病的新方法,采用激光诱导击穿光谱检测技术,快速无损诊断正常和感染炭疽病油茶叶片中的Mn元素含量,根据火焰原子吸收光谱法对样品中Mn元素的真实含量进行了分析。分别采用平滑、去噪、归一化、基线校正、一阶求导降噪、二阶求导降噪对光谱数据进行预处理,使用偏最小二乘方法(PLS)建立定量模型,采用间隔偏最小二乘法(iPLS)对光谱数据进行波段筛选。最终结合7点平滑和一阶导数降噪进行预处理,根据iPLS建立定量模型。实验结果表明,平分为24个子区间时,第6个子区间的建模效果最佳,建模相关系数为0.9076,建模均方根误差为0.2090 μg/mg,预测相关系数为0.8947,预测均方根误差为0.2100 μg/mg。
激光诱导击穿光谱 炭疽病 油茶叶片 Mn元素 激光与光电子学进展
2020, 57(9): 093006
Author Affiliations
Abstract
College of Physics and Energy, Shenzhen University, Shenzhen 518060, China
We have studied the two- and three-photon absorption (2PA and 3PA) properties of Mn-doped CsPbCl3 two-dimensional nanoplatelets (2D NPs) and cubic nanocrystals. Compared with their cubic counterparts, the Mn-doped 2D NPs exhibit stronger quantum confinement effects that can more efficiently enhance their dopant-carrier exchange interactions and multiphoton absorption. More specifically, the maximum volume-normalized 2PA and 3PA cross sections of the 2D NPs were 6.8 and 7.2 times greater than those of their cubic counterparts, respectively, reaching up to 1237 GM/nm3 in the visible light band and 2.24×10 78 cm6·s2·photon 2/nm3 in the second biological window, respectively.
Photonics Research
2018, 6(11): 11001021
Author Affiliations
Abstract
1 College of Physics and Energy, Shenzhen University, Shenzhen 518060, China
2 Department of Electrical and Electronic Engineering, South University of Science and Technology of China, Shenzhen 518055, China
3 Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
Perovskite nanocrystals (NCs) have strong nonlinear optical responses with a number of potential applications, ranging from upconverted blue-lasing to the tagging of specific cellular components in multicolor fluorescence microscopy. Here, we determine the one-photon linear absorption cross section of two kinds of blue-emitting perovskite NCs, i.e., CsPbCl3 and CsPb(Cl0.53Br0.47)3, by utilizing femtosecond transient absorption spectroscopy. The wavelength-dependent nonlinear refraction and two-photon absorption have been measured at wavelengths from 620 to 720 nm by performing Z-scan measurements. The nonlinear optical responses of CsPb(Cl0.53Br0.47)3 are much more pronounced than those of CsPbCl3 due to the larger structural destabilization of the former.
Ultrafast nonlinear optics Ultrafast spectroscopy Photonics Research
2018, 6(6): 06000554
基于自旋反转模型, 数值研究了光抽运下1300 nm自旋垂直腔面发射激光器(Spin-VCSEL)输出激光的圆偏振转换(PS)及偏振双稳(PB)特性。研究结果表明: 对于一定的抽运光偏振椭圆率PP, 抽运光功率能在一定程度上控制激光器输出光的偏振椭圆率Pout, 其绝对值随抽运光功率的增加而逐渐增大; 对于一定的归一化抽运光功率η, 采用正向扫描(逐渐增加)和反向扫描(逐渐减小)PP时, Spin-VCSEL输出的左旋圆偏振光与右旋圆偏振光之间会发生PS, 并可观察到PB现象。对于较小的η, 双稳环宽度随η的增加先增加到一个最大值然后减小到0; 对于较大的η, 双稳环宽度随η的增加总体上呈现出逐渐减小的趋势。激光器的线宽增强因子α和有源区介质的双折射系数γp等内部参数对由PP变化引起的PS和PB均有较大的影响。此外, 确定了双稳环宽度在某些激光器关键内部参数和η构成的参数空间中的分布图。
激光光学 自旋垂直腔面发射激光器 光抽运 圆偏振转换 双稳
Author Affiliations
Abstract
In conventional pulsed laser deposition (PLD) technique, plume deflection and composition distribution change with the laser incident direction and pulse energy, then causing uneven film thickness and composition distribution for a multicomponent film and eventually leading to low device quality and low rate of final products. We present a novel method based on PLD for depositing large CIGS films with uniform thickness and stoichiometry. By oscillating a mirror placed coaxially with the incident laser beam, the laser's focus is scanned across the rotating target surface. This arrangement maintains a constant reflectance and optical distance, ensuring that a consistent energy density is delivered to the target surface by each laser pulse. Scanning the laser spot across the target suppresses the formation of micro-columns, and thus the plume deflection effect that reduces film uniformity in conventional PLD technique is eliminated. This coaxial scanning PLD method is used to deposit a CIGS film, 500 nm thick, with thickness uniformity exceeding ±3% within a 5 cm diameter, and exhibiting a highly homogeneous elemental distribution.
220.0220 Optical design and fabrication 220.4830 Systems design 310.0310 Thin films 310.1860 Deposition and fabrication Chinese Optics Letters
2014, 12(7): 072201
