Spatio-spectral characteristics of ultra-broadband THz emission from two-colour photoexcited gas plasmas and their impact for nonlinear spectroscopy
Spatio-spectral characteristics of ultra-broadband THz emission from two-colour photoexcited gas plasmas and their impact for nonlinear spectroscopy
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DOI：
10.1088/1367-2630/15/7/075023
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发表时间：
2013-07-25
影响因子：
3.3
通讯作者：
Roskos, H. G.
中科院分区：
文献类型：
--
作者：
Blank, V.;Thomson, M. D.;Roskos, H. G.
我们提出了由双色飞秒光脉冲产生和驱动的气体等离子体的太赫兹（THz）和中红外发射的综合空间和光谱特性的表征。为了在非线性光谱中使用它，需要考虑相对复杂的空间剖面对宽带（类似于10太赫兹）和超宽带（>100太赫兹）发射的影响，特别是基于z扫描技术的实验。在这里，我们应用基于场自相关和和频（上转换）检测的空间分辨测量。基于这些结果，我们提出了超宽带剖面在其通过一个焦点区域的模拟。除了由于等离子体灯丝中产生机制而导致的发射轮廓的固有特征外，我们还分析了通常放置在等离子体之后的半导体（硅）晶片的作用，以丢弃光泵光束，其光激发也可以在产生的太赫兹轮廓中发挥作用。
We present a characterization of the combined spatial and spectral properties of the terahertz (THz) and mid-infrared emission from gas plasmas generated and driven by two-colour femtosecond optical pulses. For its use in nonlinear spectroscopy, the impact of the relatively complex spatial profile for both broadband (similar to 10 THz) and ultra-broadband (>100 THz) emission needs to be considered, in particular for experiments based on z-scan techniques. Here we apply spatially resolved measurements based on both field autocorrelation and sum-frequency (up-conversion) detection. Based on these results, we present simulations of the ultra-broadband profile during its passage through a focal region. In addition to the inherent features of the emission profile due to the generation mechanism in the plasma filament, we also analyse the role of the semconductor (silicon) wafer typically placed after the plasma to discard the optical pump beams, whose photoexcitation also can play a role in the resultant THz profile.