Broadband detection of laser-excited surface acoustic waves K by a novel transducer employing ferroelectric polymers

Broadband detection (150-MHz range) of surface acoustic wave transients excited by absorption of ps laser pulses in the sample under study is demonstrated. A novel transducer employing a ferroelectric polymer foil as piezoelectric sensor is described. In a silicon single crystal the width of the observed acoustic pulses was limited to 4 ns by the spatial resolution of pulse generation and detection. In the polycrystalline materials under study the minimum observable pulse width was determined by materials properties. Accurate values for the phase velocity of surface acoustic wave propagation are given for silicon, aluminum, steel, copper, and brass.