高谱分辨率宽带相干反斯托克斯拉曼散射光谱探测

发布时间：2018-11-15 17:23

【摘要】：相干反斯托克斯拉曼散射技术(Coherent anti-Stokes Raman Scattering,CARS)是基于物质分子固有振动、转动特性获取信号,因此可以在无需标记的前提下,通过光与物质相互作用产生非线性信号。CARS属于三阶非线性效应,因此具有高灵敏、高空间分辨率以及三维层析能力等特点,广泛应用于活细胞的光谱探测与显微成像中,使在自然的微环境中观测完整的样品和活体细胞成为可能。一直以来,CARS多是基于分子内某一特定化学键产生的反斯托克斯信号表征特定分子,然而,这种靠单一化学键区分细胞内种类繁多的生物分子是远远不够的。因此,为了能够准更加准确、快速地识别不同的分子,需要尽可能同时获取分子完整的CARS光谱。本文将超连续谱光源与超窄带通滤光片结合提出一种高谱分辨宽带CARS光谱探测方法,即:超短激光脉冲分为两路,一路泵浦光子晶体光纤产生的超连续谱做斯托克斯光,另一路经过窄带滤光片,得到光谱宽度约为0.7 nm,脉宽展宽至皮秒量级的激光脉冲同时作为泵浦光和探测光,两路激光脉冲合束后被显微物镜聚焦于样品上,从而产生具有高光谱分辨率的宽带CARS光谱。论文的主要创新点:1.提出一种具有高谱分辨率宽带CARS光谱探测方法,进行理论分析和数值模拟,证明方法的可行性;2.搭建了一套高谱分辨宽带CARS光谱探测系统,一次性获得苯甲腈样品分子在500-3500 cm-1范围内的6个CARS特征峰。本论文的主要内容有:1.对比传统单频CARS与宽带CARS,提出高谱分辨率宽带CARS方法。2.利用对称分步傅里叶法数值求解非线性薛定谔方程,模拟了超短激光脉冲在光子晶体光纤中传输时在时间域和频谱域的演化情况,为产生适用于高谱分辨率宽带CARS光谱探测的超连续谱光源提供了理论基础。3.基于高谱分辨宽带CARS方法,对聚苯乙烯珠与苯甲腈内多个分子共振键进行光谱探测模拟,获得聚苯乙烯珠与苯甲腈内多个分子共振键的高谱分辨率宽带CARS光谱。4.搭建了一套高谱分辨宽带CARS光谱探测系统,实现了苯甲腈样品分子振动500-3500 cm-1内多个分子共振键同时探测。
[Abstract]:The coherent anti-Stokes Raman scattering (Coherent anti-Stokes Raman Scattering,CARS) technique is based on the inherent vibration and rotational characteristics of matter molecules, so it can be used without labeling. The nonlinear signal is produced by the interaction of light and matter. CARS is a third order nonlinear effect, so it has the characteristics of high sensitivity, high spatial resolution and three-dimensional tomography, so it is widely used in the spectral detection and microscopic imaging of living cells. It is possible to observe intact samples and living cells in a natural microenvironment. All along, CARS is based on the anti-Stokes signal generated by a specific chemical bond within a molecule to characterize a particular molecule. However, it is far from enough to distinguish a wide variety of biological molecules within cells by a single chemical bond. Therefore, in order to identify different molecules more accurately and quickly, complete molecular CARS spectra should be obtained simultaneously. In this paper, a high spectral resolution wideband CARS spectral detection method is proposed by combining the supercontinuum light source with the ultra-narrow band pass filter. The ultrashort laser pulse is divided into two channels, and the supercontinuum spectrum generated by the photonic crystal fiber is pumped one way to make the Stokes light. The other way through the narrow band filter, the laser pulse with a spectral width of about 0.7 nm, pulse width up to picosecond is obtained, and the laser pulse is simultaneously used as the pump light and the detection light. The two laser pulses are combined with the beam and then focused on the sample by the microscope objective lens. Thus, broadband CARS spectra with high spectral resolution are generated. The main innovation points of this paper are as follows: 1. A broadband CARS spectral detection method with high spectral resolution is proposed. Theoretical analysis and numerical simulation are carried out to prove the feasibility of the method. 2. A set of high spectral resolution wideband CARS spectral detection system was set up. Six CARS characteristic peaks of benzonitrile samples in the range of 500-3500 cm-1 were obtained at one time. The main contents of this thesis are as follows: 1. Compared with traditional single frequency CARS and wideband CARS, a high spectral resolution wideband CARS method is proposed. 2. The nonlinear Schrodinger equation is solved numerically by using the symmetric discrete step Fourier method. The evolution of ultrashort laser pulses in the time domain and the spectrum domain is simulated when they propagate in photonic crystal fibers. It provides a theoretical basis for the generation of supercontinuum spectral light source for broadband CARS spectral detection with high spectral resolution. Based on the high spectral resolution wideband CARS method, the spectral simulation of multiple molecular resonance bonds in polystyrene beads and benzonitrile was carried out, and the high spectral resolution broadband CARS spectra of polystyrene beads and benzonitrile were obtained. 4. A high spectral resolution wideband CARS spectral detection system was set up to detect the molecular vibration of benzonitrile samples simultaneously in 500-3500 cm-1.
【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O433

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