Diffraction gratings of photosensitive ZrO_2 gel films fabricated with the two-ultraviolet-beam interference method

Abstract
Photosensitive ZrO2 gel films were patterned with a two-beam interference method by use of a 325-nm-wavelength He–Cd laser for the first time to our knowledge. The ZrO2 gel films were prepared from Zr(O-n-C4H9)4 chemically modified with benzoylacetone. We fabricated uniform gratings with a 0.5-µm period on Si or SiO2 substrates by etching the gel films in ethyl alcohol after UV irradiation. A maximum diffraction efficiency of 28% was attained with the grating fabricated on Si substrate under a Littrow mounting condition by use of a 633-nm-wavelength He–Ne laser. Blazed gratings could also be fabricated.