Abstract-Research on terahertz transmission characteristics of nonpolar liquid based on frequency-domain spectroscopy

Su-jie Guo, Cun-jun Ruan, De-yin Kong, Jun Dai, Yan Zhang, and Wen-long He

https://www.osapublishing.org/josab/abstract.cfm?uri=josab-37-7-1942

In our research, terahertz frequency-domain spectroscopy based on continuous-wave and coherent detection, which offers advantages of frequency selectivity and much higher frequency resolution, is used to acquire the optical parameter of nonpolar liquid samples in a polytetrafluoroethylene (PTFE) rectangle cell. The transfer matrix method is raised to remove the oscillation generated by the Fabry–Perot interferometer caused by the cell wall; thereby, dielectric constants of liquids can be extracted successfully. The refractive index of the nonpolar liquid samples cyclohexane (C6H12)${\mathrm{C}}_6{\mathrm{H}}_{12})$ and n$\mathrm{n}$-Hexane (C6H14${\mathrm{C}}_6{\mathrm{H}}_{14}$) are obtained within the frequency range of 400–1600 GHz. The processed results of cyclohexane and n-Hexane in our method are basically stable with a refractive index of about 1.42 and 1.37, respectively, which agrees well with the experimental results using other methods previously.

© 2020 Optical Society of America

Abstract-High resolution continuous wave terahertz spectroscopy on solid-state samples with coherent detection

De-Yin Kong, Xiao-Jun Wu, Bo Wang, Yang Gao, Jun Dai, Li Wang, Cun-Jun Ruan, and Jun-Gang Miao

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-26-14-17964

We systematically investigate the data analysis methods in terahertz frequency domain spectroscopy (THz-FDS) with coherent detection. We demonstrate that the Hilbert transform method is one of the most appropriate for data processing in THz-FDS. By converting frequency-domain signal into time domain with further data processing, the system noise due to Fabry–Pérot (FP) interference is greatly restrained. Accurate permittivity of lactose monohydrate is successfully extracted under the condition of the existence of atmospheric water vapor. Our work greatly promotes the development of THz spectroscopy in practical applications.

© 2018 Optical Society of America

Abstract-Highly efficient generation of 0.2 mJ terahertz pulses in lithium niobate at room temperature with sub-50 fs chirped Ti:sapphire laser pulses

Xiao-jun Wu, Jing-long Ma, Bao-long Zhang, Shu-su Chai, Zhao-ji Fang, Chen-Yi Xia, De-yin Kong, Jin-guang Wang, Hao Liu, Chang-Qing Zhu, Xuan Wang, Cun-Jun Ruan, and Yu-Tong Li

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-26-6-7107#top

We demonstrate generation of 0.2 mJ terahertz (THz) pulses in lithium niobate driven by Ti:sapphire laser pulses at room temperature. Employing tilted pulse front technique, the 800 nm-to-THz energy conversion efficiency has been optimized to 0.3% through chirping the sub-50 fs pump laser pulses to overcome multi-photon absorption and to extend effective interaction length for phase matching. Our approach paves the way for mJ-level THz generation via optical rectification using existing Ti:sapphire laser systems which can deliver Joule-level pulse energy with sub-50 fs pulse duration.

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement