We describe a pulsed terahertz (THz) emitter that uses a rapidly oscillating, high-voltage bias across electrodes insulated from a photoconductor. Because no carriers are injected from the electrodes, trap-enhanced electric fields do not form. The resulting uniform field allows excitation with a large laser spot, lowering the carrier density for a given pulse energy and increasing the efficiency of THz generation. Compared to a dc bias, less susceptibility to damage is observed.
© 2011 Optical Society of America
Original Manuscript: October 19, 2010
Manuscript Accepted: November 15, 2010
Published: January 12, 2011
Vol. 6, Iss. 2 Virtual Journal for Biomedical Optics
H. Zhang, J. K. Wahlstrand, S. B. Choi, and S. T. Cundiff, "Contactless photoconductive terahertz generation," Opt. Lett. 36, 223-225 (2011)