Simulations in the time and frequency domains of surface acoustic wave fields on transmission through a deeply-subwavelength-width bridge.
(a–c) Simulated amplitude of the acoustic wave propagation in a subwavelength bridge of length L = 7 μm and width W = 0.25 μm, 1.2 ns (a) 4.2 ns (b) and 5.7 ns (c) after the acoustic wave generation, shown at the surface (x, y) (upper plots) and for vertical (x, z) sections (lower plots). (a) The vertical dotted-dashed lines represent the block boundaries. The insets in (b,c) depict close-ups near the bridge region. (d,e) show the amplitudes of the temporal Fourier transform respectively off resonance at 251 MHz (η = 0.5) and on resonance at 359 MHz (η = 5.7) at the surface (x, y) (upper plots) and for vertical (x, z) sections (lower plots). (d,e) include line-plot snapshots of the average out-of-plane particle velocity plotted along the bridge-length direction (x). The colour-scale bar is the same for (a–c) and (d–e), but with a sensitivity 4 times larger for the bottom images of (d,e) compared to the top ones. (The amplitude in some places in the upper plots of (d,e) saturates the colour scale up to a factor of ~10).