Femtosecond pulse shaping in the mid-infrared generated by difference-frequency mixing: a simulation and experiment
Femtosecond pulse shaping in the mid-infrared generated by difference-frequency mixing: a simulation and experiment
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DOI：
10.1364/josab.24.001886
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发表时间：
2007-08
影响因子：
1.9
通讯作者：
M. Tsubouchi;T. Momose
中科院分区：
文献类型：
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作者：
M. Tsubouchi;T. Momose
本文从理论和实验两方面研究了差频混频产生的中红外（3-10 μm）相位和振幅调制的飞秒激光脉冲。转移的脉冲形状从近红外到MIR的差频过程进行了详细的评估，为各种光谱，线性啁啾，相位，和两个脉冲的光延迟之前，不同的频率进行比较，并与实验获得的MIR形状。在实验中，光参量放大器的信号脉冲用声光可编程色散滤波器整形，并在AgGaS 2晶体中与空闲脉冲混合，空闲脉冲通过使其穿过色散块而在时间上被拉伸，以生成整形的MIR脉冲。尽管实验过程比较复杂，但理论与实验符合较好。结果表明，所得到的MIR脉冲形状可以完全不同于差频产生之前的脉冲形状。然而，它是可能的再现任何形状的MIR脉冲通过预测脉冲形状使用本理论框架。这将使我们能够在实际应用中操纵真实的分子的振转波包。
We have examined phase- and amplitude-modulated femtosecond laser pulses in the mid-infrared (MIR) region (3-10 μm) generated by difference-frequency mixing both theoretically and experimentally. Transfer of the pulse shape from near infrared to MIR by a difference-frequency process was evaluated in detail for various spectra, linear chirps, phases, and optical delays of two pulses before the different frequency was compared and with experimentally obtained MIR shapes. In the experiment, the signal pulse of an optical parametric amplifier was shaped with an acousto-optic programmable dispersive filter and mixed in an AgGaS2 crystal with the idler pulse that was temporally stretched by passing it through a dispersion block to generate a shaped MIR pulse. The agreement between the theory and experiment was reasonable despite the complicated experimental procedure. It was demonstrated that the resultant MIR pulse shape could be completely different from the pulse shape before the difference-frequency generation. However, it is possible to reproduce any shape of MIR pulses by predicting the pulse shape using the present theoretical framework. This will allow us to manipulate rovibrational wave packets of real molecules for practical applications.