Author Affiliations
Abstract
1 Institute of Nanophotonics, Jinan University, Guangzhou 511443, China
2 e-mail: liyuchao@jnu.edu.cn
3 e-mail: zhyao5@jnu.edu.cn
We developed adjustable and movable droplet microlenses consisting of a liquid with a high refractive index. The microlenses were prepared via ultrasonic shaking in deionized water, and the diameter of the microlenses ranged from 1 to 50 μm. By stretching the microlenses, the focal length can be adjusted from 13 to 25 μm. With the assistance of an optical tweezer, controllable assembly and movement of microlens arrays were also realized. The results showed that an imaging system combined with droplet microlenses could image 80 nm beads under white light illumination. Using the droplet microlenses, fluorescence emission at 550 nm from CdSe@ZnS quantum dots was efficiently excited and collected. Moreover, Raman scattering signals from a silicon wafer were enhanced by times. The presented droplet microlenses may offer new opportunities for flexible liquid devices in subwavelength imaging and detection.
Photonics Research
2020, 8(3): 03000225
1 天津医科大学生物医学工程, 天津 300070
2 中国医学科学院生物医学工程研究所, 天津 300192
在光腔衰荡光谱技术中衰荡信号虽不受入射光强变化的影响, 但入射光强大小并非任意选取。通过理论计算结合实验分析, 探讨脉冲光腔衰荡光谱技术中激光单脉冲能量的选取, 结果显示激光脉冲能量选取受反射镜的反射率、探测器灵敏度、增益及信噪比等因素限制。当入射光强度选取过低, 在探测器本身灵敏度和信噪比的限制下, 信号被淹没于噪声中, 无法检测信号; 入射光强度过高, 输出的光电流随光强的增大而趋向于饱和, 探测器的响应呈现非线性, 甚至出现漂白现象或损坏探测器。实验中, 激光光源单脉冲能量范围在33 nJ到1 μJ较为合适。
光腔衰荡光谱 单脉冲能量 参数选择 光电倍增管 cavity ring-down spectroscopy single pulse energy parameter selection photomultiplier tube
