Abstract-Terahertz emission driven by two-color laser pulses at various frequency ratios

W.-M. Wang, Z.-M. Sheng, Y.-T. Li, Y. Zhang, J. Zhang

https://journals.aps.org/pra/abstract/10.1103/PhysRevA.96.023844

We present a simulation study of terahertz radiation from a gas driven by two-color laser pulses in a broad range of frequency ratios 

${\omega }_1/{\omega }_0$. Our particle-in-cell simulation results show that there are three series with ${\omega }_1/{\omega }_0=2n,n+1/2,n\pm 1/3$ ($n$ is a positive integer) for high-efficiency and stable radiation generation. The radiation strength basically decreases with the increasing ${\omega }_1$ and scales linearly with the laser wavelength. These rules are broken when ${\omega }_1/{\omega }_0<1$ and much stronger radiation may be generated at any ${\omega }_1/{\omega }_0$. These results can be explained with a model based on gas ionization by two linear-superposition laser fields, rather than a multiwave mixing model.

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