Electromagnetic activity of a single, subwavelength helix is explored under transverse illumination with terahertz electromagnetic pulses. By measuring the phase accrual difference between right- and left-circularly polarized components of the pulse transmitted through a series of identically shaped helices, where sections of each helix have been systematically removed, a linear relationship is discovered between the electromagnetic activity of a helix and its thickness in the propagation direction of the electromagnetic wave. A single helix is thus shown to possess intrinsic electromagnetic activity, describable by an effective circular birefringence.
© 2010 Optical Society of America
Original Manuscript: January 4, 2010
Revised Manuscript: March 2, 2010
Manuscript Accepted: March 3, 2010
Published: April 13, 2010
Kenneth�J. Chau, "Investigation of the chiral origins of electromagnetic activity," Opt. Lett. 35, 1187-1189 (2010)