Near-field dynamic study of the nanoacoustic effect on the extraordinary transmission in gold nanogratings

In this paper we report that nanoacoustic pulses can modulate the extraordinary optical transmission (EOT) in nanogratings with a high frequency bandwidth. This study was performed on gold nanogratings on top of a GaN crystal by combining a near-field scanning optical microscope with a femtosecond nanoultrasonic system. Experimental results indicate that the propagating longitudinal nanoacoustic pulses changed the refractive index of a GaN crystal and therefore modulated the near-field cavity mode behavior. Our finding suggests that the temporal modulation with a >11GHz bandwidth can be achieved, with a high potential for future temporal and high speed control on the EOT behavior in nanostructures.