Nonlinear Optics with Two-Colour Lasers

使用双色激光器的非线性光学

• 批准号: 194495-2013
• 负责人: Strickland, Donna
• 金额: $ 2.33万
• 依托单位: University of Waterloo
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=633233
• 关键词: Nonlinear; Optics; Two; Colour; Lasers

Lasers transformed optics research 50 years ago and have now spawned innumerable applications. Lasers operate at many wavelengths from the infrared to the ultraviolet, but to completely cover the optical spectrum, nonlinear optics is needed. Ultrashort pulse lasers can now generate far-infrared radiation through a nonlinear process known as optical rectification and can nonlinearly drive the frequency up to the extreme ultraviolet by high order harmonic generation. However, some spectral gaps still exist and this proposal aims to fill in the "molecular fingerpint" spectral region from 6 to 25µm, where almost every molecule has a distinctive signature in its absorption spectra. Along with applications in environmental monitoring and medical applications, this spectral region is becoming increasingly important for trace gas detection of explosives that have strong absorption lines at these wavelengths. At Waterloo, we are developing a two-colour, short pulse fiber laser system, which will generate mid-infrared wavelengths across the fingerprint region with sufficient power for trace gas detection, by difference frequency mixing the two laser outputs in a nonlinear crystal. Since the invention of the stroboscope, increasingly faster motion has been observed by ever decreasing optical pulse durations. We are proposing to generate a source of high intensity, ultra short (~2 fs) pulses that can be used to make a freeze frame movie of the vibrational motion of any molecule. To make such a short pulse, requires a wide picket fence of colours that spans the spectral region from the ultraviolet to the infrared. A two-colour, Ti:sapphire laser system will be used to generate such a wide frequency comb, through the nonlinear process of multi-frequency Raman generation. We will first study this nonlinear process so that we can optimize the many colour spectra. We will then coherently add all the colours together to create the ultra short, high intensity pulses needed to watch and measure molecular motion.

激光在50年前改变了光学研究，现在已经产生了无数的应用。激光器工作在从红外到紫外的许多波长，但要完全覆盖光谱，就需要非线性光学。超短脉冲激光器现在可以通过称为光学整流的非线性过程产生远红外辐射，并且可以通过高次谐波产生非线性地驱动频率直到极紫外线。然而，一些光谱间隙仍然存在，该提案旨在填补6至25µm的“分子指纹”光谱区域，其中几乎每个分子在其吸收光谱中都有独特的特征。沿着在环境监测和医疗应用中的应用，该光谱区域对于在这些波长处具有强吸收线的爆炸物的痕量气体检测变得越来越重要。在滑铁卢，我们正在开发一种双色短脉冲光纤激光系统，该系统将通过在非线性晶体中对两种激光输出进行差频混合，产生跨越指纹区域的中红外波长，具有足够的功率用于痕量气体检测。自从频闪观测器发明以来，通过不断减小的光脉冲持续时间，已经观察到越来越快的运动。我们建议产生一个高强度的超短（~2 fs）脉冲源，可以用来制作任何分子振动运动的定格电影。为了产生如此短的脉冲，需要一个广泛的颜色栅栏，跨越从紫外到红外的光谱区域。一个双色的钛宝石激光系统将被用来产生这样的宽频率梳，通过多频拉曼产生的非线性过程。我们将首先研究这个非线性过程，以便我们可以优化许多颜色光谱。然后，我们将相干地将所有颜色添加到一起，以创建观察和测量分子运动所需的超短，高强度脉冲。