Third Sound on Disordered Substrates

We are investigating the properties of third sound on disordered two-dimensional substrates that have position-dependent index of refraction values. To do this we have created a disordered array of third sound scatterers by depositing regions of CaF2 onto a glass slide. A second slide is uniformly coated with CaF2 for comparison. We present preliminary results for the third sound transmission spectra across the disordered and uniform regions. The disordered sample exhibits a frequency dependence which is not seen in the uniform sample. The possibility that this is due to Anderson localization is considered.