Author Affiliations
Abstract
1 State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
2 State Key Laboratory of Space-Ground Integrated Information Technology, Beijing Institute of Satellite Information Engineering, Beijing 100095, China
Polarization holography has been extensively applied in many fields, such as optical science, metrology, and biochemistry, due to its property of polarization modulation. However, the modulated polarization state of diffracted light corresponds strictly to that of incident light one by one. Here, a kind of tunable polarization holographic grating has been designed in terms of Jones matrices, and intensity-based polarization manipulation has been realized experimentally. The proposed tunable polarization holographic grating is recorded on an azobenzene liquid-crystalline film by a pair of coherent light beams with orthogonal polarization states and asymmetrically controlled intensities. It is found that the diffracted light can be actively manipulated from linearly to circularly polarized based on the light intensity of the recording holographic field when the polarization state of incident light keeps constant. Our work could enrich the field of light manipulation and holography.
Photonics Research
2024, 12(4): 749
1 中国电子科技集团公司第二十九研究所, 电磁空间安全全国重点实验室,成都 610036
2 北京真空电子技术研究所,大功率微波电真空器件技术国防科技重点实验室,北京 100016
对S波段永磁式全腔提取相对论磁控管进行了理论设计和数值模拟研究,并对其进行了实验研究。通过理论分析初步获取相对论磁控管结构参数,并采用三维电磁仿真软件对模型进行粒子仿真优化,根据引导磁场需求设计永磁磁场产生结构。该永磁式相对论磁控管在500 kV电压输入条件下,输出微波功率1.978 GW,效率49.2%。利用实验室小型脉冲功率驱动源平台开展了初步实验研究。实验中,该永磁式相对论磁控管在脉冲驱动源驱动下获得GW级输出功率,功率转换效率约40%,实验结果与模拟结果吻合得较好。
稀土永磁 相对论磁控管 高功率微波 矩形波导 脉冲驱动源 permanent magnet relativistic magnetron high power microwave rectangular waveguide pulse generator 强激光与粒子束
2024, 36(3): 033007
Author Affiliations
Abstract
1 MOE Key Laboratory of Advanced Micro-Structured Materials, School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
2 State Key Laboratory of Surface Physics, Key Laboratory of Micro- and Nano-Photonic Structures (Ministry of Education) and Department of Physics, Fudan University, Shanghai 200433, China
3 School of Optoelectronic Engineering, Guangdong Polytechnic Normal University, Guangzhou 510665, China
4 e-mail: jiang-haitao@tongji.edu.cn
5 e-mail: lshi@fudan.edu.cn
Bound states in the continuum (BICs) in artificial photonic structures have received considerable attention since they offer unique methods for the extreme field localization and enhancement of light-matter interactions. Usually, the symmetry-protected BICs are located at high symmetric points, while the positions of accidental BICs achieved by tuning the parameters will appear at some points in momentum space. Up to now, to accurately design the position of the accidental BIC in momentum space is still a challenge. Here, we theoretically and experimentally demonstrate an accurately designed accidental BIC in a two-coupled-oscillator system consisting of bilayer gratings, where the optical response of each grating can be described by a single resonator model. By changing the interlayer distance between the gratings to tune the propagation phase shift related to wave vectors, the position of the accidental BIC can be arbitrarily controlled in momentum space. Moreover, we present a general method and rigorous numerical analyses for extracting the polarization vector fields to observe the topological properties of BICs from the polarization-resolved transmission spectra. Finally, an application of the highly efficient second harmonic generation assisted by quasi-BIC is demonstrated. Our work provides a straightforward strategy for manipulating BICs and studying their topological properties in momentum space.
Photonics Research
2024, 12(4): 638
Author Affiliations
Abstract
1 MOE Key Laboratory of Advanced Micro-Structured Materials, School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
2 School of Optoelectronic Engineering, Guangdong Polytechnic Normal University, Guangzhou 510665, China
3 Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
4 Department of Electrical Engineering, Tongji University, Shanghai 201804, China
5 State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
6 e-mail: yufeiwang@semi.ac.cn
7 e-mail: yongsun@tongji.edu.cn
Metasurfaces with spin-selective transmission play an increasingly critical role in realizing optical chiral responses, especially for strong intrinsic chirality, which is limited to complex three-dimensional geometry. In this paper, we propose a planar metasurface capable of generating maximal intrinsic chirality and achieving dual-band spin-selective transmission utilizing dual quasi-bound states in the continuum (quasi-BICs) caused by the structural symmetry breaking. Interestingly, the value of circular dichroism (CD) and the transmittance of two kinds of circular polarization states can be arbitrarily controlled by tuning the asymmetry parameter. Remarkable CD approaching unity with the maximum transmittance up to 0.95 is experimentally achieved in the dual band. Furthermore, assisted by chiral BICs, the application in polarization multiplexed near-field image display is also exhibited. Our work provides a new avenue to flexibly control intrinsic chirality in planar structure and offers an alternative strategy to develop chiral sensing, multiband spin-selective transmission, and high-performance circularly polarized wave detection. The basic principle and design method of our experiments in the microwave regime can be extended to other bands, such as the terahertz and infrared wavelengths.
Photonics Research
2024, 12(2): 244
1 华中农业大学工学院, 湖北 武汉 430070 农业农村部长江中下游农业装备重点实验室, 湖北 武汉 430070
2 华中农业大学工学院, 湖北 武汉 430070 农业农村部长江中下游农业装备重点实验室, 湖北 武汉 430070农业农村部柑橘全程机械化科研基地, 湖北 武汉 430070
3 华中农业大学工学院, 湖北 武汉 430070 农业农村部长江中下游农业装备重点实验室, 湖北 武汉 430070国家现代农业(柑橘)产业技术体系, 湖北 武汉 430070农业农村部柑橘全程机械化科研基地, 湖北 武汉 430070
咪鲜胺和抑霉唑是柑橘类水果常用的保鲜剂, 二者混用可有效降低致病细菌抗药性, 达到更好的保鲜效果, 但农残过量会影响食用者健康。 基于表面增强拉曼光谱技术, 以丑橘为基质, 咪鲜胺和抑霉唑混合农药为研究对象, 结合化学计量学方法, 建立一种快速准确检测柑橘表皮农药残留的方法。 为了对比金、 银溶胶的增强效果, 分别将金、 银溶胶用于浓度为10 mg·L-1的咪鲜胺、 抑霉唑标准溶液及橘皮萃取液中的混合农药, 采集其拉曼光谱。 结果表明, 咪鲜胺和抑霉唑的单独标准溶液中金溶胶较优, 在橘皮萃取液中的混合农药溶液中银溶胶效果更佳。 为了获得最佳增强效果, 通过不同比例试验对比, 最终确定溶胶增强基底与两种农药标准溶液体积比为1∶1, 团聚剂NaCl浓度为1 mol·L-1。 按照浓度从高到低的方向, 分别采集咪鲜胺标准溶液及抑霉唑标准溶液在不同浓度情况下的光谱, 检出限分别低于1和0.5 mg·L-1, 达到国标规定的最大残留限5 mg·L-1。 在咪鲜胺和抑霉唑混合农药的定量分析实验中, 以橘皮萃取液为基质, 用增强效果较好的银溶胶作为增强基底, 采集含有梯度浓度的咪鲜胺和抑霉唑混合农药(5~42 mg·L-1)的表面增强拉曼光谱, 采用多种预处理方法优化光谱数据, 对比支持向量回归(SVR)、 灰狼算法优化的支持向量回归(GWO-SVR)、 粒子群算法优化的支持向量回归(PSO-SVR)、 遗传算法优化的支持向量回归(GA-SVR)四种回归模型的建模效果选择最佳算法建立定量模型。 结果表明: 通过一阶微分预处理方法, 选取829和1 168 cm-1处的特征峰强度建立灰狼算法优化的支持向量机回归(GWO-SVR)模型得到的预测效果最佳, 其校正相关系数(RC)为0.978, 校正集均方根误差(RMSEC)为1.655 mg·L-1, 预测相关系数(RP)为0.967, 预测集均方根误差(RMSEP)为2.227 mg·L-1。 研究结果表明, 该方法可对柑橘表皮咪鲜胺和抑霉唑混合农药进行定性与定量检测, 可为柑橘农残检测提供新思路。
表面增强拉曼光谱 柑橘 咪鲜胺 抑霉唑 支持向量机回归 Surface enhanced Raman spectroscopy Citrus Prochloraz Imazalil Support vector machine regression 光谱学与光谱分析
2023, 43(10): 3052
强激光与粒子束
2023, 35(10): 105004
红外与激光工程
2023, 52(9): 20220897
1 同济大学物理科学与工程学院先进微结构材料教育部重点实验室,上海 200092
2 山西大同大学物理与电子科学学院微结构电磁功能材料山西省重点实验室,山西 大同 037009
近年来受拓扑绝缘体启发而兴起的拓扑光子学有力地促进了电磁波调控和新型波功能器件的研究。光子人工带隙材料因其丰富的物态调控机制和高度定制化的设计自由度成为了研究拓扑光子学和研制鲁棒性光子器件的重要平台。本文主要综述了周期性二聚化以及准周期性Harper光子拓扑链中光子与人工带隙材料的相互作用,揭示了非厄密物理、宇称-时间对称转变和拓扑相变对能带和带隙的作用规律,以及光场本征态的调控和传输机制。围绕实际的共振耦合技术,介绍了非厄密拓扑物理启发下的具有拓扑保护特性的高性能近场无线传能和传感方案,并对非厄密拓扑物理对于无线传能和传感的发展将起到的作用进行了展望。
光学器件 非厄密物理 光拓扑结构 拓扑相变 无线传能 无线传感 光学学报
2023, 43(16): 1623011
Author Affiliations
Abstract
1 MOE Key Laboratory of Advanced Micro-structured Materials, School of Physics Sciences and Engineering, Tongji University, Shanghai 200092, China
2 School of Optoelectronic Engineering, Guangdong Polytechnic Normal University, Guangzhou 510665, China
3 State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
4 Department of Electrical Engineering, Tongji University, Shanghai 201804, China
5 e-mail: wujiaju@tongji.edu.cn
6 e-mail: yufeiwang@semi.ac.cn
7 e-mail: yongsun@tongji.edu.cn
Optical resonators with high quality () factors are paramount for the enhancement of light–matter interactions in engineered photonic structures, but their performance always suffers from the scattering loss caused by fabrication imperfections. Merging bound states in the continuum (BICs) provide us with a nontrivial physical mechanism to overcome this challenge, as they can significantly improve the factors of quasi-BICs. However, most of the reported merging BICs are found at point (the center of the Brillouin zone), which intensively limits many potential applications based on angular selectivity. To date, studies on manipulating merging BICs at off- point are always accompanied by the breaking of structural symmetry that inevitably increases process difficulty and structural defects to a certain extent. Here, we propose a scheme to construct merging BICs at almost an arbitrary point in momentum space without breaking symmetry. Enabled by the topological features of BICs, we merge four accidental BICs with one symmetry-protected BIC at the point and merge two accidental BICs with opposite topological charges at the off- point only by changing the periodic constant of a photonic crystal slab. Furthermore, the position of off- merging BICs can be flexibly tuned by the periodic constant and height of the structure simultaneously. Interestingly, it is observed that the movement of BICs occurs in a quasi-flatband with ultra-narrow bandwidth. Therefore, merging BICs in a tiny band provide a mechanism to realize more robust ultrahigh- resonances that further improve the optical performance, which is limited by wide-angle illuminations. Finally, as an example of application, effective angle-insensitive second-harmonic generation assisted by different quasi-BICs is numerically demonstrated. Our findings demonstrate momentum-steerable merging BICs in a quasi-flatband, which may expand the application of BICs to the enhancement of frequency-sensitive light–matter interaction with angular selectivity.
Photonics Research
2023, 11(7): 1262
Author Affiliations
Abstract
1 MOE Key Laboratory of Advanced Micro-structured Materials, School of Physics Sciences and Engineering, Tongji University, Shanghai 200092, China
2 School of Space Science and Physics, Shandong University, Weihai 264209, China
3 State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
4 Department of Electrical Engineering, Tongji University, Shanghai 201804, China
5 e-mail: yufeiwang@semi.ac.cn
6 e-mail: jiang-haitao@tongji.edu.cn
7 e-mail: dgqql@sdu.edu.cn
8 e-mail: yongsun@tongji.edu.cn
Recently, the concepts of parity–time (PT) symmetry and band topology have inspired many novel ideas for light manipulation in their respective directions. Here we propose and demonstrate a perfect light absorber with a PT phase transition via coupled topological interface states (TISs), which combines the two concepts in a one-dimensional photonic crystal heterostructure. By fine tuning the coupling between TISs, the PT phase transition is revealed by the evolution of absorption spectra in both ideal and non-ideal PT symmetry cases. Especially, in the ideal case, a perfect light absorber at an exceptional point with unidirectional invisibility is numerically obtained. In the non-ideal case, a perfect light absorber in a broken phase is experimentally realized, which verifies the possibility of tailoring non-Hermiticity by engineering the coupling. Our work paves the way for novel effects and functional devices from the exceptional point of coupled TISs, such as a unidirectional light absorber and exceptional-point sensor.
Photonics Research
2023, 11(4): 517