Temporal Response of a Plasmonic Antenna

Using femtosecond lasers, we investigate the temporal response of a plasmonic antenna [1]. This structure is fabricated by Capasso's group. In this report, we propose an application of such a plasmonic antenna:\textbf{ femtosecond electron switching}. The plasmonic antenna may be very effective in influencing the motion of free electrons because the intensity of an input electric field can be enhanced by up to a factor of a thousand in the near field [2]. Our estimates indicate that the plasmonic antenna can cause large deflection angles of about 0.1 radian upon applying a 10 nJ, 10 femtosecond duration laser pulse. Therefore, a low power, high repetition rate femtosecond laser may be used to excite the plasmonic structure and influence electrons' motion at the femtosecond time scale, leading to a femtosecond electron switch. We want to experimentally determine this dynamical response of the antenna. A preliminary test of the plasmonic antenna shows that it can respond in the femtosecond regime. Detection schemes that are sensitive to about 10 femtoseconds are now being explored. [1] Elizabeth J. Smythe, Ertugrul Cubukcu, and Federico Capasso, \textit{Opt. Exp.} \textbf{15}, 7439 (2007) [2] Ertugrul Cubukcu, et \textit{al.}, \textit{IEEE J. Sel. Top. Qu. Elec.}, Vol.14, No.6, 1448 (2008)