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Updated: Feb 16, 2026

Design, Fabrication, and Experimental Characterization of Plasmonic Photoconductive Terahertz Emitters
Published on: July 8, 2013
Observation of Terahertz Radiation via the Two-Color Laser Scheme with Uncommon Frequency Ratios
Liang-Liang Zhang1, Wei-Min Wang1,2,3, Tong Wu4
1Beijing Advanced Innovation Center for Imaging Technology and Key Laboratory of Terahertz Optoelectronics (MoE), Department of Physics, Capital Normal University, Beijing 100048, China.
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 ω_{2}/ω_{1}=1:2. We investigate THz generation with uncommon frequency ratios. Our experiments show, for the first time, efficient THz generation with new ratios of ω_{2}/ω_{1}=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 multiwave mixing theory, but support the gas-ionization or plasma-current 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.
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