Construction of THz-pulse characterization tools

• Main Authors: Shiau-Ting Huang, 黃筱庭
• Other Authors: Jiunn-Yuan Lin
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/03971206723907582744

碩士 === 國立中正大學 === 物理所 === 97 === The region of the electromagnetic spectrum with frequencies between 10^11 and 10^13 Hz is called the terahertz (THz) region. Recently, numerous of THz radiation has be demonstrated in chemical, physical, and biological. So the development of high power and broadband THz sources becomes an important research topic and will attract more new techniques using such sources. In this thesis, we construct a THz source with four-wave mixing by using BBO crystal in our laboratory, and we can choose the transmitting spectral band by using various materials as filters. Moreover, we establish three detection systems to detect the THz waves including the automatic scanning of the software, and acquisition programs. First, a Fourier transform spectrometer is used to measure the THz wave waveform and find the THz wave spectrum. With spectrum analysis tool, we verify that using the GaAs wafer can not only reflect the visible light but also limit the transmitting frequency band to 8~20 um. Second, Photoconducting switch is used to detect the pulse duration of THz wave and THz wave focal spot size. The pulse duration is measured to be 175 fs and the focal spot of 1000 um is found when THz wave is focused by a OAP with a 278-mm focal length. Third, four-wave mixing in air is also employed to detect the pulse duration. The measured pulse duration of 150 fs agrees well with that measured by the former technique.