2D and 3D laser writing for integrated optical elements creation

We report on laser writing of 2D and 3D structures based on laser induced structural modifications. In our experiment, bulk glasses of chalcogenide systems Ga-Ge-S, As₂S₃ and Ga-Ge-S thin films have been used. Photo-structuring of the bulk glasses has been obtained by using low energy (< 2.5 nJ) fs laser pulses with wavelength of 815 nm, while the films have been photo-structured by using both fs and nitrogen lasers. Spherical structures in the bulk glasses have been found whose geometrical form and size depend on both the sample translation velocity and the laser pulse energy. With increasing the sample translation velocity up to 3cm/s, and for values of the average laser power of 150 mW, the spherical structures disappear and flat waveguides are created. The manufacturing laser threshold for bulk chalcogenide glasses was found to be about 2 · 10¹⁰ W/cm². For the case of films irradiated by the nitrogen laser a blue shift of the optical absorption edge and a decrease of the refractive index were measured. The considerable and controllable change of the optical parameters allowed us to create waveguides showing the possibility of realizing integrated optical circuits with high density of elements.