Figure 1

The scheme of spectrum-tunable narrowband acoustic phonon spectroscopy. Schematics of the experimental setup of the frequency and bandwidth tunable narrowband acoustic phonon spectroscopy using the intensity-modulated optical pump pulse. The sandwiched-layer sample (sample type 1) was used for the acoustic transport measurement by the opposite-side pump-probe geometry. The nanoscale W thin film (sample type 2) was used for the study of mechanical resonant eigen-mode excitation by the same-side pump-probe geometry.