The present disclosure is related to a method of fabricating a semiconductor device involving the production of at least two non-parallel nano-scaled structures on a substrate. These structures are heated to different temperatures by exposing them simultaneously to polarized light having a wavelength and polarization such that a difference in absorption of light occurs in the first and second nanostructure. In some cases the light is polarized in a plane that is parallel to one of the structures. The present disclosure may provide differential heating of semiconductor structures of different materials, such as Ge and Si fins.