We investigated optical, structural, and chemical properties of SiOxNy layers irradiated by CW IR laser during a time lapse of few milliseconds. We observed tunable photoluminescence signal at room temperature in the range 750–950 nm, without Si/SiO2 phase separation, depending on the IR laser power irradiation. Furthermore, no photoluminescence signal was recorded when the IR laser power density was high enough to promote phase separation forming Si quantum dots. By chemical analysis the source of the luminescence signal has been identified in a change of silicon chemical environment induced by IR laser annealing inside the amorphous matrix.