Films of porous silica are deposited on the uniform waists of tapered fibers in minutes by a modified solgel dip coating method, inducing less than 0.2 dB of loss. The coated tapers are an ideal platform for realizing all-fiber devices that exploit evanescent-field interactions with the deposited porous film. As an example we demonstrate structural long-period gratings in which a periodic index variation in the film arises from the porosity variation produced by spatially varying exposure of the waist to a scanned CO<sub>2</sub> laser beam. The long period grating is insensitive to temperature up to 800 °C.
© 2004 Optical Society of America
G. Kakarantzas, *S. G. Leon-Saval, T. A. Birks, and P. St. J. Russell, "Low-loss deposition of solgel-derived silica films on tapered fibers," Opt. Lett. 29, 694-696 (2004)