Two-dimensional periodic structures were fabricated upon a fluorine-doped SiO<sub>2</sub> film in which the fluorine content changed gradually in the direction of film thickness. The films were deposited by plasma-enhanced chemical-vapor deposition. The film was periodically patterned into a 1-μm period and an ~1-μm -groove depth by inductive coupled plasma reactive-ion etching followed by chemical etching in a diluted HF solution. A surface reflectance of 0.7% was attained at 1.85-μm wavelength, a value that is one fifth as large as the 3.5% Fresnel reflection of a SiO<sub>2</sub> substrate with a flat surface.
© 2001 Optical Society of America
(050.1970) Diffraction and gratings : Diffractive optics
(160.6030) Materials : Silica
(220.4000) Optical design and fabrication : Microstructure fabrication
(230.4000) Optical devices : Microstructure fabrication
(310.1210) Thin films : Antireflection coatings
K. Kintaka, J. Nishii, A. Mizutani, H. Kikuta, and H. Nakano, "Antireflection microstructures fabricated upon fluorine-doped SiO2 films," Opt. Lett. 26, 1642-1644 (2001)