We used a pulsed laser (femtosecond) focused by means of a microscope objective into the surface of a polymer-plastic sample. By carefully controlling the input power (or energy per pulse) of the laser and exposure time, local modifications of the refractive index were obtained.
The resulted features resulted upon refractive index modifications were then investigated by using Confocal Laser Scanning Microscopy (CLSM) both in reflection and fluorescence (excitation beam @488 nm). The results are displayed below.
Furthermore, the local modifications were investigated via Atomic Force Microscopy (AFM) and scattering Scanning Near-field Optical Microscopy (s-SNOM). The images from s-SNOM were post-processed and used for obtaining the refractive index and extinction coefficient maps. These results are shown below.
These results confirm that the changes of the complex refractive index were successfully obtained.