Thomson Mark D, Blank Volker, Roskos Hartmut G
Physikalisches Institut, J. W. Goethe-Universit¨at, Max-von-Laue-Str 1, 60438 Frankfurt am Main, Germany.
Opt Express. 2010 Oct 25;18(22):23173-82. doi: 10.1364/OE.18.023173.
We demonstrate plasma-THz generation in ambient air with two-color (ω-2ω) optical excitation using input pulses with a bandwidth supporting sub-20-fs duration, yielding a continuous bandwidth exceeding 100 THz with no significant roll-off and a pulse energy of 360 nJ at a 1-kHz repetition rate. The key aspect in achieving this performance is an optimized geometry of the second-harmonic generation (SHG) crystal, producing a 2ω-field detuned from the second-harmonic of the ω-field, which promotes both a high polarization bandwidth and optimal ω-2ω temporal overlap in the plasma, as supported by theoretical results.
我们展示了在环境空气中利用双色（ω - 2ω）光激发产生等离子体太赫兹波，使用带宽支持亚20飞秒持续时间的输入脉冲，产生了连续带宽超过100太赫兹且无明显滚降的信号，在1千赫兹重复频率下脉冲能量为360纳焦。实现这种性能的关键在于二次谐波产生（SHG）晶体的优化几何结构，产生一个与ω场的二次谐波失谐的2ω场，这促进了等离子体中高极化带宽和最佳的ω - 2ω时间重叠，理论结果也支持这一点。
