Abstract-Terahertz coherent detection via two-color laser pulses of various frequency ratios

Xin-Yang Gu, Ke-Jia Wang, Zhen-Gang Yang, Jin-Song Liu,

https://iopscience.iop.org/article/10.1088/1674-1056/ab37fc/pdf

The mechanism of terahertz (THz) pulse coherent detection via two-color laser pulses of various frequency ratios in gas plasma is theoretically investigated. Our investigations demonstrate that except for the commonly used frequency ratio of 2, other uncommon frequency ratios can also be utilized to detect THz pulse, such as 2n, n+1/2(n≤3, n is a positive integer). The well-developed transient photocurrent model is extended to our terahertz detection process. Based on this model, our simulation results can be explained by analyzing the process of asymmetric electron ionization and electron acceleration.

Abstract-Method for defect contour extraction in terahertz non-destructive testing conducted with a raster-scan THz imaging system

Cheng-Wu You, Chengchangfeng Lu, Tian-Yi Wang, Shun-Rong Qian, Zhen-Gang Yang, Ke-Jia Wang, Jin-Song Liu, and Sheng-Lie Wang



https://www.osapublishing.org/ao/abstract.cfm?uri=ao-57-17-4884&origin=search

In this paper, a neoteric algorithm based on a two-dimensional continuous wavelet transform is developed to get the defect contour in the terahertz (THz) non-destructive testing result obtained from a raster-scan frequency-modulated continuous-wave (FMCW) THz imaging system. In order to prove the method’s validity, an experiment is carried out. The result of the experiment shows that the method allows one to extract the defect contour from the THz FMCW interference with severe stripe noises. Moreover, the relative error of defect area between the actual value and that obtained from the extracted defect contour is no more than 3.03%. This means that the method provided an effective and exact way to extract a defect contour in THz FMCW interference.

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