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.
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