Development of Circularly Polarized Light Source in the Terahertz-wave Region with Coherent Transition Radiation

Research Project

Project/Area Number	24651099
Research Category	Grant-in-Aid for Challenging Exploratory Research
Allocation Type	Multi-year Fund
Research Field	Quantum beam science
Research Institution	Kyoto University
Principal Investigator	TAKAHASHI TOSHIHARU 京都大学, 原子炉実験所, 准教授 (00273532)
Project Period (FY)	2012-04-01 – 2015-03-31
Project Status	Completed (Fiscal Year 2014)
Budget Amount *help	¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000) Fiscal Year 2013: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000) Fiscal Year 2012: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Keywords	電子線型加速器 / 放射光 / 遷移放射 / コヒーレント / 円偏光 / テラヘルツ / ミリ波
Outline of Final Research Achievements	For the spectroscopic purpose, various types of coherent radiation emitted from a relativistic electron beam have attracted a considerable attention as a new and powerful light source in the THz-wave region. Coherent transition radiation (CTR) is one of such a light source. Whereas synchrotron radiation has linear polarization along an electron orbit, the electric vector of transition radiation (TR) emitted from a metallic screen is axially symmetric with respect to the trajectory of an electron beam. Therefore, CTR is usually utilized as a non-polarized light source in the spectroscopic application. However, circularly polarized light has been useful in the circular dichroism spectroscopy. In this study a new technique of generation of circularly polarized THz radiation using two kinds of linearly polarized CTR with horizontal and vertical components. The polarization degree can be easily controlled by changing the phase difference between the two CTRs.