The 0-order transmission of a 1D metallic grating, on a high-resistivity silicon wafer in optical contact with a silicon plate, has been characterized by terahertz time-domain spectroscopy with subpicosecond resolution over a 400 ps scan range. Two new long-time-delay, powerful pulses are observed after the second reflected pulse. In the frequency domain, these two strong and fast-ringing structures correspond to the bandwidth ranges between the [0, 1] and [0, 2] surface plasmon modes and the range above [0, 2], respectively. A physical optics ray analysis provides an intuitive understanding of these new four-step (reflection, diffraction, total reflection, and diffraction) pulses, caused by fractional-order surface plasmon type beam coupling.
© 2012 Optical Society of America
Optics at Surfaces
Original Manuscript: March 6, 2012
Manuscript Accepted: March 23, 2012
Published: May 14, 2012
Yuping Yang and D. Grischkowsky, "Four-step pulses of fractional-order surface plasmons," Opt. Lett. 37, 1709-1711 (2012)