Laser-excited 100-GHz localized acoustic modes in Au/V nanolayer structures

This work presents analysis of localized acoustic modes using theory given by B. Djafari-Rouchani et al. and Rytov model of elastic waves propagation in periodical medium. Localized modes were considered for Au/V nanostructures. Experimentally Au/V nanostructures on MgO substrate with period 120-240 Å were studied. Changes of light reflectivity coefficient of these nanostructures caused by femtosecond laser beam excitation were measured. Analysis of experimental results of reflectivity dependence on delay time of probe beam was made over the range up to 150 ps. The dependences of localized modes frequency on thickness of nanostructure bilayers were obtained. Measured frequencies of localized modes remain in agreement to the theoretical values.