During the INTEGRAOPTIC research project development, we modified the surface refractive indices by tip-enhancement of a pulsed laser beam at the tip of a micro-probe. We have succeeded in creating very small (sub-200 nm) modified refractive index zones. These areas can be controlled very precisely, creating photonic structures with special optical properties, adapted for various applications such as guiding the light according to the desired direction.
The obtained structures were investigated by near-field scanning micro-probe microscopy. The images obtained were used for the 3D reconstruction and representation of the investigated devices.
We also studied how the refractive index depends on the power of the incident laser. Thus, low laser energies lead to small changes in the refractive index over a smaller dimensional area. The obtained changes are non-linear, but they are in agreement with theoretical expectations. For example, the refractive index changes following the local occurrence of the depolymerization phenomenon, which, taking into account the parameters of the experiment, theoretically leads to the same variation of the refractive index obtained experimentally.
