1 中国科学院上海光学精密机械研究所高功率激光物理重点实验室，上海 201800
2 中国科学院大学，北京 100049
基于亚纳秒间隔的皮秒激光双脉冲，研究了双脉冲时域整形对K9玻璃表面烧蚀特性的调控规律。当子脉冲间隔为667 ps时，不同形状双脉冲下玻璃表面的烧蚀形貌随激光通量增加的变化规律明显不同，而泵浦通量起着决定性作用。当泵浦通量低于阈值时，双脉冲烧蚀特性基本与单脉冲相似；当泵浦通量在阈值附近时，泵浦脉冲对玻璃表面的微纳米尺度的烧蚀会显著增强探测脉冲的烧蚀效应。当泵浦通量高于1.3倍阈值时，泵浦脉冲在玻璃与空气界面附近产生冲击波，探测脉冲被冲击波的高密度前沿界面反射和干涉，在中心烧蚀区域周围产生了圆环状烧蚀形貌，且圆环分布与探测通量密切相关。双脉冲烧蚀的内径尺寸与泵浦通量相关，而外径尺寸与双脉冲的形状、通量均相关。对比研究了子脉冲间隔为333 ps和667 ps时的等通量双脉冲烧蚀形貌，结果发现：低通量下较小的脉冲间隔可以增强烧蚀效应；高于烧蚀阈值的泵浦脉冲会影响探测脉冲的能量沉积；两种脉冲间隔下环状形貌的不同反映了泵浦脉冲产生的冲击波的传输特性不同。最后基于实验结果讨论了双脉冲序列时域整形进行表面烧蚀调控的物理机制。
激光技术 激光烧蚀 皮秒激光 双脉冲 时域整形 中国激光
2023, 50(12): 1202201
西安理工大学陕西省超快光电技术与太赫兹科学重点实验室, 陕西西安 710048
多带太赫兹超材料吸收器是响应、操纵和调制太赫兹波的重要光子元件。本文基于周期性分裂环谐振器结构构建了一种多带太赫兹超材料吸收器。模拟和实验测试显示, 在横磁 (TM)极化情况下该超材料吸收器对 0.918 THz和 1.581 THz处的入射太赫兹波呈现出近似完美吸收。进一步, 基于器件共振吸收峰的介电敏感特性, 研究了负载不同浓度的多菌灵、三环唑、百草枯、塞苯隆 4种农药溶液后超材料吸收器的传感性能, 获得器件对 4种农药的检测灵敏度分别为: 1.06 GHz/ppm、 0.65 GHz/ppm、 0.67 GHz/ppm、 2.07 GHz/ppm。结果表明该器件可实现对微量农药的传感检测, 为今后食品质量安全控制提供了新的思路。
太赫兹 超材料 痕量农药 传感器 terahertz metamaterials trace pesticides sensor 太赫兹科学与电子信息学报
2022, 20(11): 1107
Author Affiliations
Abstract
1 Key Laboratory of Ultrafast Photoelectric Technology and Terahertz Science in Shaanxi, Xi’an University of Technology, Xi’an 710048, China
2 Key Laboratory of Engineering Dielectric and Its Application, Ministry of Education, Harbin University of Science and Technology, Harbin 150080, China
3 College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China
4 e-mail: wangyue2017@xaut.edu.cn
5 e-mail: fengxp@zju.edu.cn
The promising prospect of a terahertz metasurface in sensing and detection applications has attracted increasing attention because of its ability to overcome the classical diffraction limit and the enhancement of field intensity. In this work, a novel scheme based on an all-silicon terahertz plasmon metasurface is proposed and experimentally demonstrated to be a highly sensitive biosensor for the Bacillus thuringiensis Cry1Ac toxin. The regression coefficients between Bacillus thuringiensis protein concentrations and the spectral resonance intensity and frequency were 0.8988 and 0.9238, respectively. The resonance amplitude variation and frequency shift of the metasurface were investigated in terms of both thickness and permittivity change of the analyte, which reflected the protein residue in the actual process. Moreover, the reliability and stability of the metasurface chip were verified by time period, temperature, and humidity control. These results promise the ability of the proposed metasurface chip as a Bacillus thuringiensis protein sensor with high sensitivity and stability. In addition, this novel device strategy provides opportunities for the advancement of terahertz functional applications in the fields of biochemical sensing and detection.
Photonics Research
2022, 10(3): 03000740
1 哈尔滨理工大学工程电介质及其应用教育部重点实验室, 黑龙江 哈尔滨 150080
2 西安理工大学理学院, 陕西 西安 710048
提出了一种复合结构三频带太赫兹超材料吸收器,其对特定频率的入射太赫兹波呈现出完全吸收的特性。设计的超材料吸收器在入射角度达到50°时仍能保持良好的吸收特性。利用干涉理论分析了完美吸收发生的条件以及介质层介电常数对吸收频率的影响。进一步利用传输线理论结合干涉理论,分析了耶路撒冷十字短边长度对吸收特性的影响,结果表明:随着短边长度增加,吸收峰发生红移。实验结果与仿真、干涉理论、传输线理论中得到的结果吻合得较好,为今后超材料吸收器的设计提供了指导。
太赫兹技术 光谱学 超材料 干涉 传输线
Author Affiliations
Abstract
1 Key Laboratory of High Power Laser and Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 University of Chinese Academy of Sciences, Beijing 100049, China
It is rare for a conventional direct detection method to measure the transmittance uniformity of mirrors with rigorous standards, especially to meet the requirement of transmittance/reflectance and phase detection simultaneously. In this study, a new method of self-calibrated balanced heterodyne detection (SCBHD) is proposed. It can be self-calibrated by a two-channel structure to overcome the environmental effects in large optics scanning detection by employing highly accurate heterodyne interference. A typical transmittance measurement experiment was performed at 1053 nm wavelength via SCBHD. A standard deviation (SD) of 0.038% was achieved in the preliminary experiment. The experimental results prove to reduce the SD by approximately two orders of magnitude compared with the conventional direct detection method in the same condition. The proposed method was verified as being promising not only for its wider dynamic measurement range and its higher accuracy but also for its simultaneous transmittance and phase detection ability.
120.3940 Metrology 240.6700 Surfaces 300.6490 Spectroscopy, surface Chinese Optics Letters
2018, 16(6): 061201
1 中国科学院上海光学精密机械研究所高功率激光物理重点实验室, 上海 201800
2 中国科学院大学, 北京 100049
表面微小疵病在用不同波长的光照明时,其光学图像会存在不同程度的非线性放大畸变现象,对成像信息中的目标提取和信噪比(SNR)将产生一定的影响。提出利用红、绿、蓝三基色光源辐照下的疵病图像进行动态彩色编码成像的方法,经像素级图像融合后可实现高冗余信息的图像合成,从而在获取表面微小疵病丰富细节的同时可进一步提高信噪比。分析了针对三基色图像进行彩色编码的理论,提出了基于图像梯度的动态权值融合成像方法,同时给出了光谱非线性放大信号的噪声分析模型,通过理论分析和数值模拟两方面,充分验证了动态权值融合降低标准偏差的有效性。在明场表面疵病成像实验中,采用三基色平衡响应的彩色互补金属氧化物半导体(CMOS)相机,分别获取了单个微米量级表面疵病点的三基色滤波图像,并通过与传统边缘提取、非动态权值组合等方法的结果比对,验证该优化方法可得到一幅细节更为丰富的高SNR图像。在暗场表面疵病成像实验中,以图像灰度平均梯度和提取到的疵病数量为评价参数,即从优化图像质量和疵病识别能力两个方面,进一步验证该优化在高保真和低噪声方面的有效性。提出的动态彩色编码融合成像方法可有效降低光谱非线性放大带来的噪声。
光学器件 表面疵病 动态彩色编码 高功率激光技术
Author Affiliations
Abstract
1 Key Laboratory of High Power Laser and Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 University of Chinese Academy of Sciences, Beijing 100049, China
A universal phase mismatch compensation method, which can be applied to temperature-insensitive frequency conversion, is experimentally demonstrated. In this method, two nonlinear crystals and an electro-optic crystal are cascaded. The generated phase mismatch in the nonlinear crystal can be well compensated for in the electro-optic crystal, thereby improving the stability of frequency conversion. In the proof-of-principle experiment, temperature-insensitive second and third harmonic generation (SHG and THG) are investigated by cascading KH2PO4 (KDP) and KD2PO4 (DKDP) crystals. The experimental results show that the temperature acceptance bandwidths of SHG and THG are 2.1 and 2.3 times larger, respectively, than that of the traditional method employing a single crystal. Meanwhile, the effectiveness of this method is also analyzed at a high power density, and a solution for the case of a nonuniform temperature is also discussed. Furthermore, angle-insensitive SHG is demonstrated to prove that this method can significantly reduce the influence of various unfavorable factors on frequency conversion. The demonstrated method may have potentially important applications in the nonlinear optical frequency conversion system.
Nonlinear optics second and third harmonic generation (SHG and THG) cascaded nonlinear processes Collection Of theses on high power laser and plasma physics
2016, 14(1): 6100308
Author Affiliations
Abstract
1 Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 University of Chinese Academy of Sciences, Beijing 100049, China
A compensation method for phase mismatch caused by temperature variation during the frequency conversion process is proposed and the theoretical model is established. The method is based on the principle that phase mismatch can be compensated via the electro-optic effect based on a compensation scheme consisting of two nonlinear crystals and an electro-optic crystal; further, a new dimension adjustment can be achieved by changing the voltage. In a proof-of-principle study, frequency conversion from 1053 nm to 526.5 nm and 351 nm by cascade KH2PO4 (KDP) and KD2PO4 (DKDP) crystals, respectively, is presented as an example. Three-dimensional numerical simulations are conducted to show that the conversion efficiency of frequency doubling and tripling varies with temperature. The results show that the temperature acceptance bandwidth of doubling and tripling can be 2.4 and 3.4 times larger, respectively, than that of the traditional method using a single crystal. We also analyze the stability of the conversion efficiency for 192 beams by our proposed method when the temperature is randomly varied within the range of 24°C–26°C. The standard deviation of the conversion efficiency of frequency doubling and tripling decreases from 1.25% and 6.61% to 0.18% and 0.56%, respectively. In addition, the influence of the reflection loss on the output efficiencies is also analyzed and the results show that it is very small. This indicates that this method may be effective in reducing the temperature sensitivity of conversion efficiency.
Lasers frequency doubled Harmonic generation and mixing Nonlinear wave mixing. Collection Of theses on high power laser and plasma physics
2016, 14(1): 525
Author Affiliations
Abstract
中国科学院上海光学精密机械研究所高功率激光物理联合实验室, 上海 201800
Influence of charge coupled device (CCD)′ s nonlinear response characteristics on the near-field and far-field beam quality′ s measurement of high power laser system is analyzed. A new calibration method, based on single slit diffraction, is presented to calibrate CCD′ s photoelectric characteristics. Accomplish the calibration of a given CCD and restore the grey level of near-field and far-field energy distribution by the calibration curve in ideal and practical system to observe the influence on the measurement of near-field fill factor (FF) and far-field encircled energy distribution. The restoration shows that in a certain laser system the near-field FF will improve 1% ~2% after the grey level restoration. And it has nearly no influence on the farfield energy distribution parameters.
激光器 光束质量 电荷耦合器件 单缝衍射 非线性特性 近远场 灰度修复 lasers beam quality charge coupled device (CCD) single slit diffraction nonlinear characterization near-field and far-field grey level restoration Collection Of theses on high power laser and plasma physics
2015, 13(1): 0402001
中国科学院上海光学精密机械研究所高功率激光物理联合实验室, 上海 201800
对利用电荷耦合器件(CCD)测量高能激光系统近远场能量分布时，CCD 光电响应非线性特性对光束质量评价的影响进行分析计算。提出了一种基于单缝衍射的CCD 光电响应标定方法，完成对某CCD 的标定工作。利用该标定结果分别对理论模拟及实际系统下的近远场能量分布进行灰度修复，考察灰度修复对近场填充因子(FF)及远场环围能量分布的影响。对实际光束的修复结果表明，经过灰度修复的近场填充因子会提高1 %~2 %，对远场评价基本无影响。
激光器 光束质量 电荷耦合器件 单缝衍射 非线性特性 近远场 灰度修复
