Figure 12.
Normalised acoustic energy spectrum of the incident quasi-monochromatic acoustic pressure wave detected (a) before and (b) after it propagates through the bulk of water surrounding a nanorod showing the nonlinear generation of acoustic waves at harmonic frequencies of the incident acoustic pressure wave. The frequency is normalised to frequency of the incident wave. The peak amplitude of the incident wave is 5 MPa. The insets show the same spectra plotted in a decibel scale. (c,d) Simulated plasmon-enhanced intensity BLS signal produced from acoustic signals with the spectra shown in Panels (a,b). Note an approximately 35-fold enhancement due to plasmonic properties of a nanorod.