Author Affiliations
Abstract
Key Laboratory of Light Field Manipulation and Information Acquisition, Ministry of Industry and Information Technology, and Shaanxi Key Laboratory of Optical Information Technology, School of Physical Science and Technology, Northwestern Polytechnical University, Xi’an 710129, China
Noble metallic nanostructures with strong electric near-field enhancement can significantly improve nanoscale light–matter interactions and are critical for high-sensitivity surface-enhanced Raman spectroscopy (SERS). Here, we use an azimuthal vector beam (AVB) to illuminate the plasmonic tips circular cluster (PTCC) array to enhance the electric near-field intensity of the PTCC array, and then use it to improve SERS sensitivity. The PTCC array was prepared based on the self-assembled and inductive coupled plasmon (ICP) etching methods. The calculation results show that, compared with the linearly polarized beam (LPB) and radial vector beam excitations, the AVB excitation can obtain stronger electric near-field enhancement due to the strong resonant responses formed in the nanogap between adjacent plasmonic tips. Subsequently, our experimental results proved that AVB excitation increased SERS sensitivity to 10-13 mol/L, which is two orders of magnitude higher than that of LPB excitation. Meanwhile, the PTCC array had excellent uniformity with the Raman enhancement factor calculated to be . This kind of vector light field enhancing Raman spectroscopy may be applied in the field of sensing technologies, such as the trace amount detection.
surface-enhanced Raman spectroscopy plasmonic tips circular cluster array azimuthal vector beam surface plasmon polaritons Chinese Optics Letters
2023, 21(3): 033603
Author Affiliations
Abstract
1 MOE Key Laboratory of Material Physics and Chemistry under Extraordinary Conditions and Shaanxi Key Laboratory of Optical Information Technology, School of Physics Science and Technology, Northwestern Polytechnical University, Xi’an 710072, China
2 MOE Key Laboratory of Weak-Light Nonlinear Photonics, TEDA Applied Physics Institute and School of Physics, Nankai University, Tianjin 300457, China
We present the generation of the nanosecond cylindrical vector beams (CVBs) in a two-mode fiber (TMF) and its applications of stimulated Raman scattering. The nanosecond (1064 nm, 10 ns, 10 Hz) CVBs have been directly produced with mode conversion efficiency of ~18 dB (98.4%) via an acoustically induced fiber grating, and then the stimulated Raman scattering signal is generated based on the transmission of the nanosecond CVBs in a 100-m-long TMF. The transverse mode intensity and polarization distributions of the first-order Stokes shift component (1116.8 nm) are consistent with the nanosecond CVBs pump pulse.
vector beam stimulated Raman scattering fiber grating Chinese Optics Letters
2021, 19(1): 010603
1 西北工业大学理学院陕西省光信息技术重点实验室, 陕西 西安 710072
2 西北工业大学理学院超常条件材料物理与化学教育部重点实验室, 陕西 西安 710072
光纤结构光场作为光场调控的一个重要分支,逐渐引起了研究者们的广泛关注。首先基于光纤矢量模式理论,讨论了光纤中具有空间偏振/相位奇异特性的结构光场的产生机理;然后,介绍了光纤结构光场的产生方法,如长周期光纤光栅耦合法、光纤端面微结构法和轨道角动量转换法等;最后,介绍了光纤结构光场在超分辨成像、涡旋光通信、等离子针尖纳米聚焦和非线性频率转换等方面的一些典型应用。
物理光学 光场调控 矢量光场 涡旋光场 模式耦合
1 新疆大学资源与环境科学学院, 教育部绿洲生态重点实验室, 新疆 乌鲁木齐 830046
2 北京联合大学应用文理学院城市系, 北京 100083
通过对新疆阜康500水库下游的盐渍化土壤实地定点取样和光谱测量, 利用光谱变换、 相关分析等方法, 定量探讨了不同人为干扰程度的土壤盐分、 水分与光谱反射率之间的关系, 并建立了土壤反射光谱与盐分含量之间的多元线性回归预测模型。 结果表明: (1)人为干扰程度与土壤盐分呈极显著正相关, 而与土壤水分呈极显著负相关, 相关系数分别为0961和-0929。 (2)在不同干扰程度与土壤光谱反射率的关系中, 重度干扰的土壤反射率比轻度干扰土壤的反射率高10%, 比未干扰高17%。 这是由于人为干扰破坏了土壤表面的少量植被及生物、 物理结皮, 土壤表层因缺乏保护, 水分会迅速蒸发, 并将土壤下部的盐分带到上部, 加之降水稀少, 盐分在表层聚集。 干扰程度越高, 结皮破坏越严重, 土壤积盐越多, 反射率越高。 (3)随干扰程度的不断增加, 土壤原始光谱反射率与盐分相关系数的两个最大值逐渐向近红外波段偏移(999, 876~979, 1 182~1 370和1 900 nm), 这预示着, 在近红外区土壤光谱反射率对盐分含量更为敏感。 (4)利用反射率R、 反射率一阶导数R′、 反射率R+水分分别建立了不同干扰程度的三类土壤盐分含量预测模型。 综合R2和RMSE判断模型精度, 在不同干扰程度下, 同类型的土壤含盐量预测模型中, 干扰程度越小, 模型精度越高; 而在相同干扰程度下, 不同类型的土壤含盐量预测模型中, 均以一阶导数R′建立的模型预测效果最优, R2均超过0983。 总体上, 模型精度提高了5%~10%, 表明原始光谱经过一阶导数变换处理, 可以去除部分线性背景值的干扰, 提高预测土壤含盐量的精度。
干扰程度 盐渍土 反射光谱特征 Degrees of disturbance Soil salinity Spectral characteristics
1 郑州大学物理工程学院,中国河南,郑州,450052
2 郑州市骨科医院,中国河南,郑州,450052
用分光光度计测定癌细胞吸收光谱,通过三种不同试验条件的比较,结果表明:参比池中采用2.8 ml蒸馏水+0.1 ml血清+0.1 ml PBS缓冲液时,能得到癌细胞具体、准确的信息,并且重现性较好,峰位及峰值强度的方差分别为0.6099、0.0238.
分光光度计 吸收光谱 癌细胞 spectrophotometer absorption spectrum cancer cells