Nanoscale Thermal Transport Studied With Heterodyne Picosecond Thermoreflectance

We present in this paper a new pump-probe thermore-flectance technique, which is called heterodyne as it uses two slightly frequency shifted lasers instead of a mechanical translation stage as used in the homodyne classical technique. The great advantage of the heterodyne technique is to avoid many artifacts leading to erroneous thermal parameter identifications. The principle and set-up are described as well as the model. Then, after presenting the identification procedure, it has been applied to the study of nanometric SiO₂ layer.