We demonstrate a technique for measuring pulse propagation time delays with 0.5-fs resolution by use of a widely available 100-fs pulsed laser. Using this technique, we measured the time delay of a light pulse transiting through subwavelength apertures placed on a 0.3-μm metallic film. We measured a 7-fs total transit time, corresponding to an effective group velocity of <i>c</i>/7 . The experimental result yielded additional evidence that light interacts resonantly with oscillators formed by the surface modes near the small apertures.
© 2001 Optical Society of America
(050.1950) Diffraction and gratings : Diffraction gratings
(240.6680) Optics at surfaces : Surface plasmons
(260.5740) Physical optics : Resonance
(320.7100) Ultrafast optics : Ultrafast measurements
A. Dogariu, T. Thio, L. J. Wang, T. W. Ebbesen, and H. J. Lezec, "Delay in light transmission through small apertures," Opt. Lett. 26, 450-452 (2001)