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arXiv 1302.3208physics.opticsphysics.atom-phphysics.plasm-ph
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强场光泵浦探测实验中的双光束耦合效应

Effect of two-beam coupling in strong-field optical pump-probe experiments

J. K. Wahlstrand, J. H. Odhner, E. T. McCole, Y. -H. Cheng, J. P. Palastro, R. J. Levis, H. M. Milchberg

摘要:

测量由强泵浦脉冲在弱探测脉冲中引起的相移的非线性光学实验必须考虑相干效应,该相干效应仅在泵浦脉冲和探测脉冲在时间上重叠时发生。众所周知,弱探测光束经历比泵浦光束自身引起的更大的来自强泵浦光束的相移。增强相移背后的物理机制是泵浦光通过两束光之间的干涉产生的非线性折射率光栅衍射到探测方向。对于瞬时三阶响应,光栅的效果是简单地使探针相移加倍,但是当考虑延迟非线性时,效果更加复杂。本文对稀有气体和双原子气体中简并和非简并泵浦探测实验作了全面的处理。将数值计算的结果与最近的瞬时双折射测量进行比较[Loriot等人,Opt.Express 17,13429(2009)]和最近的光谱干涉测量实验[Wahlstrand等人,A 85,043820(2012)]。我们还提出了两个新的实验结果,使用光谱分辨瞬态双折射与800 nm脉冲在Ar和空气和退化啁啾脉冲光谱干涉术在Ar。这两个实验都支持解释的负双折射在高强度所产生的等离子体光栅。

英文摘要:

Nonlinear optics experiments measuring phase shifts induced in a weak probe pulse by a strong pump pulse must account for coherent effects that only occur when the pump and probe pulses are temporally overlapped. It is well known that a weak probe beam experiences a greater phase shift from a strong pump beam than the pump beam induces on itself. The physical mechanism behind the enhanced phase shift is diffraction of pump light into the probe direction by a nonlinear refractive index grating produced by interference between the two beams. For an instantaneous third-order response, the effect of the grating is to simply double the probe phase shift, but when delayed nonlinearities are considered, the effect is more complex. A comprehensive treatment is given for both degenerate and nondegenerate pump-probe experiments in noble and diatomic gases. Results of numerical calculations are compared to a recent transient birefringence measurement [Loriot et al., Opt. Express 17, 13429 (2009)] and a recent spectral interferometry experiment [Wahlstrand et al., Phys. Rev. A 85, 043820 (2012)]. We also present results from two new experiments using spectrally-resolved transient birefringence with 800 nm pulses in Ar and air and degenerate chirped pulse spectral interferometry in Ar. Both experiments support the interpretation of the negative birefringence at high intensity as arising from a plasma grating.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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