We investigate the mechanism of elliptically polarized terahertz (THz) pulse generation in femtosecond two-color laser-produced plasma. In the case of in-line laser focusing, we observe the THz polarization evolves from linear to elliptical with increasing plasma length. This ellipticity arises from two combined effects—successive polarization rotation of local THz plasma sources, caused by laser phase and polarization modulations, and the velocity mismatch between laser and THz, which produces an elliptical THz pulse from a series of time-delayed, polarization-rotating local THz fields.
© 2013 Optical Society of America
Original Manuscript: January 10, 2013
Manuscript Accepted: January 26, 2013
Published: March 20, 2013
Yong Sing You, Taek Il Oh, and Ki-Yong Kim, "Mechanism of elliptically polarized terahertz generation in two-color laser filamentation," Opt. Lett. 38, 1034-1036 (2013)