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题名	基于级联四波混频多色飞秒激光的产生和应用
作者	王鹏
文献子类	博士
导师	刘军
关键词	级联四波混频 Cascaded four-wave mixing 三阶非线性效应 third-order nonlinear process 多色飞秒激光 multicolored femtosecond sidebands 对比度测量 temporal contrast measurement
其他题名	Generation and application of multicolored sidebands based on cascaded four-wave mixing
英文摘要	自从激光器发明以来，非线性光学得到广泛和深入的研究。级联四波混频是一种三阶非线性效应，基于级联四波混频在透明三阶非线性材料中可以一次性获得多个空间上分离且频率不同的飞秒激光脉冲，产生的飞秒激光脉冲光谱可以覆盖紫外到近红外，中心波长可调节，而且产生装置经济简单。一方面，这些波长可调的飞秒激光脉冲在超快光谱学和超快显微成像领域有着重要的应用，另一方面，由于级联四波混频这种三阶非线性效应对入射光强度的依赖性，可以使用其信号光直接作为三阶互相关信号光对入射光时域对比度进行测量，此外三阶非线性效应会使得信号光的时域对比度得到提高，这样干净的飞秒激光脉冲在对比度测量和提升领域具有实用价值。 本论文主要是针对固体中级联四波混频多色飞秒激光的产生和其在对比度测量领域中的应用展开研究，主要的研究内容和取得的成果如下： 1，基于25 fs钛宝石放大器，在厚度0.15 mm的白宝石片中通过级联四波混频作用获得至少八个频率上转换信号光，四个频率下转换信号光，他们的光谱总的覆盖范围从410 nm到950 nm。一级频率上转换信号光的能量最高可以达到8 μJ，是当时获得的最高能量的级联四波混频信号光；而且整个实验装置可以搭建在30*30 cm2的光学平板上，非常的经济紧凑。 2，基于级联四波混频，我们利用空气中飞秒成丝展宽光谱的激光脉冲和钛宝石放大器出射的原始脉冲在厚度0.1 mm的白宝石片中获得中心波长可调的飞秒多色激光。空气成丝展宽光谱的使用，使得装置简单经济，可应用于宽脉宽窄脉冲的输出激光。调节空气成丝的入射光能量可以改变信号光的中心波长，而在中心波长的调节过程中多色激光可以维持较高的能量输出，比如二级频率上转换信号光的能量可以维持在0.2 μJ 以上。多色信号光的总光谱覆盖500 nm到950 nm，每级信号光光谱的半高全宽都在37 nm以上。 3，在N-WG280 Schott玻璃中基于级联四波混频产生了总光谱覆盖范围从377 nm到970 nm的多色飞秒激光脉冲。从40 fs钛宝石放大器出射光首先使用两枚熔融石英薄片展宽光谱，这一从670 nm到900 nm的宽光谱激光脉冲为后续的级联四波混频过程扩展了所获得的多色激光的光谱范围。 4，由钛宝石放大器中出射的25 fs激光脉冲，经过截止频率800 nm的双色镜分束后，分别使用柱面镜聚焦重合到宝石片中，在级联四波混频的作用下，可以产生百μJ量级的多色飞秒激光，这样的高能量输出使得多色飞秒激光的应用更广；同时我们提出了一种新机制解释了伴随着多色激光产生过程中出现的多枚三倍频信号光生成。 5，基于级联四波混频，我们搭建了一套扫描式对比度测量三阶互相关仪，它的装置简单，测量动态范围已经可以达到1010；同时我们利用级联四波混频的一级频率转换信号光作为干净的采样光，设计了一套单发式对比度测量装置。; Nonlinear optics is widely studied since the invention of laser in 1960. Several spatially separated and wavelength-tunable femtosecond pulses from ultraviolet (UV) to near-infrared (NIR) can be generated based on cascaded four-wave mixing (CFWM) which is a third-order nonlinear process. The setup for the sideband generation is very economical. The generated multicolored ultrashort sidebands are expected to be used in various research fields like ultrafast spectroscopy and microscopy. As a signal of the third-order nonlinear process, the first-order sideband can be used as third-order correlation signal to characterize the temporal contrast of the input pulse directly. The temporal contrast of the sideband would be improved which make it a promising sample pulse for single-shot contrast measurement of high-intensity laser pulses. This dissertation focuses on the generation of multicolored sidebands based on CFWM and their application on temporal contrast measurement of high-intensity laser pulses. Main results and innovation points in the dissertation can be summarized as follows: 1, High-energy tunable multicolored femtosecond sidebands are generated simultaneously in a 0.15-mm-thick sapphire plate by using CFWM process directly after a 25-fs Ti:sapphire laser. More than eight frequency up-conversion sidebands and four frequency down-conversion sidebands are observed with a spectral range from 550 to 950 nm. The pulse energy of the ?rst-order sideband can reach as high as 8 μJ. The experimental setup is simple and compact , which is ?xed on a 30*30 cm2 plate board. 2, Tunable intense multicolored femtosecond sidebands are generated in a 0.1-mm-thick sapphire plate based on CFWM by using a spectrally broadened pulse from filamentation in air and a 806 nm fundamental pulse from a Ti:sapphire laser amplifier. By using the filamentation to extend the spectrum of one incident pulse, the experimental setup is compact and inexpensive. Furthermore, the spectra of the sidebands can be conveniently tuned by varying the input power for the filamentation generation, and even the second-order frequency up-conversion sideband can maintain its output power higher than 0.2 mW. The generated sidebands are observed with a spectral range from 500 to 950 nm, and each spectrum has a full width half maximum bandwidth above 37 nm, which have potential applications in ultrafast spectroscopy and microscopy. 3, The generation of multicolored sidebands with the spectrum from 377 to 970 nm in a 0.5-mm-thick N-WG280 Schott glass based on a CFWM process is demonstrated. A pulse with a broadened spectrum from 670 to 900 nm is generated by utilizing two 0.18-mm-thick fused silica glass plates and is used to provide two input beams for the CFWM process. The new frequency components generated from the self-phase modulation effect in the two thin glass plates contribute to the broadening of the total spectral range of the generated multicolored sidebands. 4, Fundamental pulse from a 25-fs Ti:sapphire laser is split by a dichroic mirror with the central wavelength of 800 nm and then focused by cylindrical mirrors in the glass. Multicolored sidebands with the energy of more than 100 μJ are generated based on CFWM, which make the sidebands more useful. The generation of THG sidebands is explained. 5, We build a third-order cross-correlator to measure the temporal contrast of laser pulse based on CFWM. The setup is very simple with the dynamic range of 1010. A single-shot cross-correlator is also designed by using the first-order sideband from CFWM as the sample pulse.
学科主题	光学工程
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/30920]
专题	中国科学院上海光学精密机械研究所
作者单位	中国科学院上海光学精密机械研究所
推荐引用方式 GB/T 7714	王鹏. 基于级联四波混频多色飞秒激光的产生和应用[D].

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