Abstract 2 Ulrichs
In this talk I will discuss the observation of coherent elastic dynamics in a nano-scale phononic crystal excited by light. I will demonstrate how ultra-short light pulses with a length of 40 fs are converted into coherent 0:5 THz elastic waves which persist over about 20 ps. Although the system under investigation has only a small number of spatial periods, the periodicity strongly manifests in the wave physics. To further illustrate this I will show how by breaking the translational invariance of the crystal, this features can be suppressed.