物理学报2016，Vol.65Issue(11)：110701-1-110701-5,5.DOI:10.7498/aps.65.110701
激光等离子体太赫兹辐射源的频率控制∗
Frequency control of the broadband ultrashort terahertz source generated from the laser induced plasma by two-color pluses
摘要
Abstract
The terahertz (THz) radiation becomes an attractive light source utilized in molecular dynamic spectroscopy, remote sensing, medicine, communication and fundamental research. The controlling of the THz spectrum is necessary for the applications. In this paper, a method is proposed for controlling the terahertz spectra generated from the laser induced plasma by two-color pluses based on the contribution of plasma oscillation. The plasma current oscillation can shift the THz spectrum when the length of medium is less than plasma skin depth. Experimentally we use a short length of molecules by means of the molecular beam method. We investigate the changing spectrum of broadband ultrashort terahertz THz generated from a jet of nitrogen (N2) molecules pumped with the two-color laser pulses following the varying plasma density and plasma length. With the increase of plasma density and the decrease of the plasma length, we observe the increase of THz central frequency (0.8–1.4 THz) and the broadening of the THz spectral width (0.78–1.53 THz). The analysis and the calculation show that the THz spectrum changes due to the frequency and the width of the plasma resonance. This scheme of controlling the THz spectrum by changing the plasma density and length is easier to implement and do not need to use complex shaped optical pulses. The discovery provides a new way of controlling the low-frequency broadband THz spectrum.关键词
太赫兹/超快强激光场/等离子体振荡频率Key words
terahertz/ultrashort laser field/plasma oscillation frequency引用本文复制引用
李娜,白亚,刘鹏..激光等离子体太赫兹辐射源的频率控制∗[J].物理学报,2016,65(11):110701-1-110701-5,5.基金项目
国家自然科学基金(批准号:11274326,61521093,61405222,11134010,11127901)和国家重点基础研究发展计划(批准号:2011CB808103)资助的课题.@@@@* Project supported by the National Natural Science Foundation of China (Grant Nos.11274326,61521093,61405222,11134010,11127901) and the National Basic Research Program of China (Grant No.2011CB808103) （批准号:11274326,61521093,61405222,11134010,11127901）
