Frequency Down-Conversion of Optical Pulse to the Far Infrared and THz Frequency Ranges Due to the Cascading Process in a Medium with a Quadratic Nonlinear Response

Applied Sciences

Dmitry M. Kharitonov¹  Mikhail V. Fedotov¹  Yongqiang Yang²  Vyacheslav A. Trofimov² 

[1] Faculty of Computational Mathematics and Cybernetics, Lomonosov Moscow State University, Leninskye Gory, Moscow 119992, Russia;School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510641, China;

关键词: frequency down-conversion;    cascading processes;    infrared optics;    terahertz optics;   

DOI  :  10.3390/app12083891

来源: DOAJ

【 摘 要 】

Difference-frequency generation is a well-known method of obtaining IR and THz radiation. It has many practical applications, such as sensing, optical metrology, diagnostics, detection and identification of substances, etc. One of the generation methods is based on the three-wave interaction in a medium with second-order nonlinear susceptibility. In this study, we investigated a special case of the frequency down-conversion into IR and THz ranges of the frequencies: the frequencies of interacting waves were multiple. We analyzed theoretically two cases of three-wave interactions: amplification of the infrared (or THz) radiation (incident weak intensity of a wave at this frequency) and a wave generation with the difference-frequency (incident zero-value intensity at this frequency). The amplification efficiency could achieve 75% and the maximal frequency conversion efficiency is about 25%. The computer simulation results made for the femtosecond pulse interaction in a crystal with the wavelength 4, 10, and 24 μm demonstrates applicability of such a scheme for the frequency down-conversion. This scheme of the THz radiation generation is a perspective tool for its application in the screening system for the detection and identification of substances.

【 授权许可】

Unknown