SYSTEM AND METHOD FOR PERMANENTLY WRITING A DIFFRACTION GRATING IN A LOW PHONON ENERGY GLASS MEDIUM

摘要

A system and method for permanently writing diffraction gratings in low p honon energy glass waveguides are shown. Ultrashort light pulses are generat ed and made to form two beams synchronously superimposed in the waveguide, t herefore forming an interference pattern corresponding to the desired gratin g. The light pulses are focussed so that the light intensity in the waveguid e exceeds a filamentation threshold. The exposure of the waveguide to these light pulses is controlled temporally and spatially in order to limit detrim ental thermal effects induced by the high-intensity pulses in the glass medi um of the waveguide.