The initial embedded clusters are preferably spherical (yellow cartoon). After irradiation by a laser, the cluster expands and its shape changes to a non-spherical configuration (orange cartoon). The corresponding optical response splits in two parts (green and magenta dots) depending of the analyzing direction with respect to the laser polarization (in green: parallel direction; in magenta: perpendicular direction). From G. Seifert et al., Appl. Phys. B 71, 795 (2000).