Figure 4

Acoustic excitation of mechanical resonance modes of W film. (a) The measured signals of differential transient reflectivity from W film induced by narrowband acoustic phonons at various driving frequencies from 126 to 458 GHz. (b) The calculated signals of differential strain on the surface of W film at corresponding driving frequencies. (c) The amplitude of the acoustic response in W film as a function of driving frequency, red dots are measured data and blue curve is calculated data.