Abstract-The Enhanced Third Harmonic Superradiation of Smith Purcell Terahertz radiation source

 Sen Gong, Tao Zhao, Shenggang Liu, Zhenhua Wu, Pengfei Hu, Min Hu, Yueheng Cao, Xiaoqiuyan 

Zhang

https://ieeexplore.ieee.org/document/8510515

Here we propose a new method to enhance the third harmonic of superradiant Smith-Purcell. In this paper, the specific designed grating structure enhances the power of the third harmonic by suppressing the second harmonic. Therefore, the higher frequency radiation signal (25 mW, 326 GHz) is generated by the lower energetic electron beam (9 keV)passing through the grating with larger size (0.4 mm), compared with normal superradiation by using PIC simulation. Accordingly, this mechanism is expected to achieve more efficient compact and tunable terahertz radiation sources with higher frequency.

Abstract-Uncertainty in Terahertz Time-Domain Spectroscopy Measurement of Liquids

http://link.springer.com/article/10.1007/s10762-016-0318-1

Terahertz time-domain spectroscopy (THz-TDS) is a significant technique for characterizing materials as it allows fast and broadband measurement of optical constants in the THz regime. The measurement precision of the constants is highly influenced by the complicated measurement procedure and data processing. Taking THz transmission measurement of liquids into account, the sources of error existing in THz-TDS process are identified. The contributions of each source to the uncertainty of optical constants in THz-TDS process are formulated, with particular emphasis on the effect of multilayer reflections and plane wave assumption. As a consequence, an analytical model is proposed for uncertainty evaluation in a THz-TDS measurement of liquids. An actual experiment with a Di 2-Ethyl Hexyl Phthalate (DEHP) sample is carried out to show that the proposed model could be a basis to evaluate the measurement precision of optical constants of liquids.