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GENERATION OF MULTIFREQUENCY/ULTRASHORT OPTICAL PULSES BASED ON TWO COLOR STIMULATED RAMAN EFFECT AND ITS APPLICATION TO ANALYTICAL CHEMISTRY

基于双色受激拉曼效应的多频/超短光脉冲的产生及其在分析化学中的应用

基本信息

批准号：
06555255
负责人：
IMASAKA Totaro
金额：
$ 9.98万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1996
项目状态：
已结题

项目摘要

In this study, we investigated multifrequency/ultrashort laser emission generated based on the two-color stimulated Raman effect that we originally found. In order to achieve this aim, high-order rotational Raman lines should be generated by using a transform-limited femtosecond laser pulse.We first confirmed that we could generate many rotational and vibrational lines by using a transform-limited excimer laser (248nm, 120fs). We also investigated the effects of laser polarization and hydrogen pressure in detail. On the other hand, more than 40 high-order pure rotational lines could be exclusively generated when we used a Ti : sapphire laser (800nm, 200-1000fs) as a pump beam. This result implies that a 0.4-fs laser pulse can, in theory, be generated. However, strong self phase modulation and self focusing occurred, when the pulse width was reduced to 200fs. Thus we had to increase the pulse width to 800fs to obtain the above result. In order to avoid this problem, we may have to use a seed beam and/or a low-temperature para-hydrogen to enhance the rotational lines in the future. We also discussed various effects affecting the generation of the rotational lines and tried to understand the nonlinear phenomena in the femtosecond regime systematically.In this study, we also develop a method for measurements of the pulse width of the ultrashort laser emission, which is based on self phase modulation. The decrease of the pulse width, hence the increase of the peak power, increased the spectral which and then this effect was concluded to be used for the measurements of the laser pulse width in the femtosecond regime.We also developed a multi-color laser for illumination works ; an etalon was inserted in the dye laser cavity and also a Nd : YAG laser was used as a pump beam for the generation of high-power multi-color laser emission for practical use.

在这项研究中，我们研究了我们最初发现的基于双色受激拉曼效应产生的多频/超短激光发射。为了实现这一目标，需要利用有限变换飞秒激光脉冲产生高阶转动拉曼谱线。我们首先证实了利用有限变换准分子激光(248 nm，120fs)可以产生许多转动和振动谱线。我们还详细研究了激光偏振和氢压的影响。另一方面，当我们使用钛宝石激光器(800 nm，200-1000fs)作为泵浦光束时，我们可以独一无二地产生40多条高阶纯转动谱线。这一结果意味着，从理论上讲，可以产生0.4fs的激光脉冲。然而，当脉冲宽度减小到200fS时，出现了较强的自相位调制和自聚焦。因此，我们必须将脉冲宽度增加到800fS才能获得上述结果。为了避免这个问题，将来我们可能不得不使用种子束和/或低温对氢来增强旋转线。我们还讨论了影响旋转线产生的各种因素，试图系统地理解飞秒系统中的非线性现象。在本研究中，我们还发展了一种基于自相位调制的超短激光脉冲宽度的测量方法。脉冲宽度的减小，峰值功率的增大，增加了激光脉冲的光谱宽度，这一效应可用于测量飞秒激光脉冲宽度。我们还研制了一台用于照明工作的多色激光器，在染料激光腔中插入标准具，并用Nd：YAG光作为泵浦光束，产生了实用的高功率多色激光发射。