Single-pulse coherently controlled nonlinear Raman spectroscopy and microscopy
Single-pulse coherently controlled nonlinear Raman spectroscopy and microscopy
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DOI：
10.1038/nature00933
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发表时间：
2002-08-01
期刊：
影响因子：
64.8
通讯作者：
Silberberg, Y
中科院分区：
文献类型：
--
作者：
Dudovich, N;Oron, D;Silberberg, Y
分子振动具有反映分子结构的振荡周期，因此被用作检测和鉴定的光谱指纹。目前，所有的非线性光谱方案都使用两个或更多个激光束来测量这种振动（1）。持续时间短于典型分子振动周期的超短（飞秒）光脉冲的可用性使得能够使用单个脉冲（2）相干激发分子振动。在这里，我们在液相中的几个分子上进行单脉冲振动光谱，其中激发和读出过程都是由同一个脉冲进行的。单脉冲光谱学的主要困难在于，所有能量在脉冲带宽内的振动能级都被激发。我们实现了高光谱分辨率，近两个数量级优于脉冲带宽，通过使用量子相干控制技术。通过适当地调制脉冲的光谱相位，我们能够利用多个路径之间的量子干涉来选择性地填充给定的振动能级，并使用相同的脉冲来探测该填充。该方案，使用一个单一的宽带激光源，是特别有吸引力的非线性显微镜的应用，我们证明了通过构建一个相干反斯托克斯拉曼（汽车）显微镜与一个单一的激光束操作。
Molecular vibrations have oscillation periods that reflect the molecular structure, and are hence being used as a spectroscopic fingerprint for detection and identification. At present, all nonlinear spectroscopy schemes use two or more laser beams to measure such vibrations(1). The availability of ultrashort (femtosecond) optical pulses with durations shorter than typical molecular vibration periods has enabled the coherent excitation of molecular vibrations using a single pulse(2). Here we perform single-pulse vibrational spectroscopy on several molecules in the liquid phase, where both the excitation and the readout processes are performed by the same pulse. The main difficulty with single-pulse spectroscopy is that all vibrational levels with energies within the pulse bandwidth are excited. We achieve high spectral resolution, nearly two orders of magnitude better than the pulse bandwidth, by using quantum coherent control techniques. By appropriately modulating the spectral phase of the pulse we are able to exploit the quantum interference between multiple paths to selectively populate a given vibrational level, and to probe this population using the same pulse. This scheme, using a single broadband laser source, is particularly attractive for nonlinear microscopy applications, as we demonstrate by constructing a coherent anti-Stokes Raman (CARS) microscope operating with a single laser beam.