We investigated the role of Nitrogen in the luminescence emission of amorphous SiO x N y layers irradiated by Infrared Laser. Variable content of Nitrogen (0-22%) has been obtained by magnetron sputtering or plasma enhanced chemical vapor deposition techniques. We demonstrate that emission is obtained from the amorphous matrix and the emission peak shifts towards longer wavelengths with increasing the N concentration. The peak shift is associated with the formation of O-Si-N chemical combinations. In contrast, no red shift was observed when N is absent.