Observation of terahertz radiation via the two-color laser scheme with uncommon frequency ratios

Liang-Liang Zhang, Wei-M. Wang, Tong Wu, Rui Zhang, Shi-J. Zhang, Cun-Lin Zhang, Yan Zhang, Zheng-Ming Sheng, Xi-Cheng Zhang

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Abstract

In the widely-studied two-color laser scheme for terahertz (THz) radiation from a gas, the frequency ratio of the two lasers is usually fixed at w2/w1=1:2. We investigate THz generation with uncommon frequency ratios. Our experiments show, for the first time, efficient THz generation with new ratios of w2/w1=1:4 and 2:3. We observe that the THz polarization can be adjusted by rotating the longer-wavelength laser polarization and the polarization adjustment becomes inefficient by rotating the other laser polarization; the THz energy shows similar scaling laws with different frequency ratios. These observations are inconsistent with multi-wave mixing theory, but support the gas-ionization model. This study pushes the development of the two-color scheme and provides a new dimension to explore the long-standing problem of the THz generation mechanism.
Original languageEnglish
Article number235001
Number of pages6
JournalPhysical Review Letters
Volume119
Issue number23
DOIs
Publication statusPublished - 8 Dec 2017

Keywords

  • THZ radiation
  • lasers
  • polarization

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