Abstract-High spatial resolution diffraction diagnostics for intense terahertz sources

Shang-Qing Li, Jing-Long Ma, Xiao-Jun Wu, Bao-Long Zhang, Chen Ou-Yang, Tian-Ze Wang, Dan Wang, Xuan Wang, Yu-Tong Li

https://arxiv.org/abs/1910.05714

We propose a high resolution spatial diagnostic method via inserting a millimeter-gap grating into the collimated terahertz beam to monitor the minute variation of the terahertz beam in strong-field terahertz sources, which is difficult to be resolved in conventional terahertz imaging systems. To verify the method, we intentionally fabricate tiny variations of the terahertz beam through tuning the iris for the infrared pumping beam before the tilted pulse-front pumping (TPFP) setups. The phenomena can be well explained by the the theory based on tilted pulse front technique and terahertz diffraction. We believe our observation not only help further understand the mechanism of intense terahertz generation, but also may be useful for strong-field terahertz applications.

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