Fabrication of a thin film phase grating assisted by surface acoustic waves

Nakagawa et al, found in fabricating the Ta2O5 amorphous thin film by sputt ering, that the refractive index and the photoelastic constant of the thin film are emphasized by the "diffused-out" electric field of the surface aco ustic wave and that there, a phase grating is generated in which the thin f ilm thickness, as well as the internal refraction index, vary periodically. This phenomenon is new and very interesting. This study intends to apply t he power of surface acoustic waves. A thin film phase grating is fabricated , the mechanism of generation is analyzed, and engineering applications to optical devices are tested. Large variations of 1.78% at the maximum in the film thickness and 5.9% in the refraction index are obtained. The fabricat ion of a precise two-dimensional grating is easy. (C) 1999 Scripta Technica .