Visualizing coherent phonon propagation in the 100 GHz range: A broadband picosecond acoustics approach

Building on a 1 kHz amplified Ti: sapphire laser source, we developed a novel pump-probe setup for broadband picosecond acoustics using a white-light continuum probe coupled to an optical multichannel analyzer. The system allows one to access, in a single measurement, acoustic parameters such as sound velocity and attenuation all over the bandwidth of the acoustic wave-packet launched by the pump pulse. We use the setup to measure the sound attenuation in fused silica and observe a dynamic crossover occurring at approximate to 170 GHz. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3532961]