Thick Si/SiO2 multilayered films with Rat interfaces are needed to achieve optical devices with low optical propagation losses, such as a laminated polarization splitter operating at a I 550 nm wavelength. Such films can be realized by a sputtering method using an Ar/H-2 gas mixture because of the successful reduction of internal stress and surface roughness of films compared with those of conventional ones. We fabricate 350 mu m thick Si:H/SiO2-x:H multilayered films having Rat interfaces by such a hydrogenation technique. The absorption losses at 1 550 nm wavelengths of both films measured separately are negligibly small.