title: Terahertz emission from surface-immobilized gold nanospheres.
abstract: Electromagnetic wave emission based on optical rectification at terahertz (THz) wavelengths was observed from surface-immobilized gold nanospheres (SIGNs) above a gold surface. Although the excitation wavelength is off-resonant with the localized surface plasmons, the THz emission field was observed to be approximately 4.8 times greater than that from a percolated gold thin film of 10 nm thickness. A theoretical calculation predicts that the light electric field is enhanced in the SIGN system, even at off-resonance wavelengths. The observed THz field amplitude was quadratic with the illumination light field, suggesting that the THz generation is due to a second-order nonlinear optical process.
authors.affiliation: Department of Electronics and Applied Physics, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Nagatsuta, Yokohama 226-8502, Japan. kajikawa@ep.titech.ac.jp
authors.forename: Kotaro
authors.initials: K
authors.lastname: Kajikawa
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nagai
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Uchiho
authors.forename: Gopakumar
authors.initials: G
authors.lastname: Ramakrishnan
authors.forename: Nishant
authors.initials: N
authors.lastname: Kumar
authors.forename: Gopika K P
authors.initials: GK
authors.lastname: Ramanandan
authors.forename: Paul C M
authors.initials: PC
authors.lastname: Planken