Resolving dynamics of acoustic phonons by surface plasmons

We show that the dynamics of acoustic phonons generated by femtosecond impulsive optical excitation can be clearly resolved by a surface plasmon technique, with enhanced sensitivity orders of magnitude higher than regular optical probe measurements. Our calculations confirm that the enhanced sensitivity is an intrinsic property of the surface plasmon probe. Therefore, the surface plasmon technique is a promising tool to detect small signal changes in optical and mechanical properties on a microscopic scale.