The non-absorbing window is adopted in the 915nm semiconductor laser to improve the catastrophic optical damage level of the device. The non-absorbing window is fabricated by impurity free vacancy diffusion induces quantum well intermixing based on SiO2 thin film technology. The theory of the impurity free vacancy diffusion induces quantum well intermixing will be systematic researching. And the different experimental conditions such as the annealing temperature, the thickness of SiO2 thin film, the refractive index of SiO2 film and the cover gaps are evaluated in the paper. And the mechanism is discussed for the effect of the porosity SiO2 film dielectric film in the impurity free vacancy diffusion induces quantum well intermixing. Ultimately the experiment results show that a luminescence blue shift 53 nm is obtained from the sample The optimal experimental conditions are annealing at 875℃ for 90s, and the thickness of the SiO2 thin film is 200 nm with the refractive index is 1.447, choosing GaAs cap piece to be the cover gap.