In order to actively control the motion of electrons in atoms and molecules, it is very advantageous to use single attosecond pulses because the natural timescale of the motion of electrons in atoms and molecules is on the order of attosecond. We generate single attosecond pulses by the polarization gating method, more specifically, the double optical gating (DOG) method [1,2].  Furthermore, in order to make the best use of the vectorial property of attosecond electric field, it is strongly desired to control the polarization state of the single attosecond pulses.  Since the aligned molecular ensemble has birefringence, it can be potentially used as an optical device available in the extreme-ultraviolet and soft-x-ray regions to control the polarization state of single attosecond pulses.

[1]     Hiroki Mashiko, Steve Gilbertson, Chengquan Li, Sabih D. Khan, Mahendra M. Shakya, Eric Moon, and Zenghu Chang, “Double optical gating of high-order harmonic generation with carrier-envelope phase stabilized lasers,” Phys. Rev. Lett. 100, 103906 (2008).

[2]     Ximao Feng, Steve Gilbertson, Hiroki Mashiko, He Wang, Sabih D. Khan, Michael Chini, Yi Wu, Kun Zhao, and Zenghu Chang, “Generation of isolated attosecond pulses with 20 to 28 femtosecond lasers,” Phys. Rev. Lett. 103, 183901 (2009).