Abstract

A new technique has been developed for the incorporation in modified chemical vapor deposition (MCVD) of low-vapor-pressure compounds into the core of optical fibers. This has resulted in low-loss rare-earth erbium fibers (see Fig. 1). In this process an organic solvent and TEOS are used to dissolve organometallics as rare-earth acetylacetonates and aluminum or gallium butoxide. The liquid is then nebulized into a fine mist with a 1.5-MHz transducer, which produces aerosol particles with a size distribution peaked near 5 µm. This permits the convenient transport of the aerosol from the aerosol generator through a rotating seal into the MCVD substrate tube, as shown in Fig. 2. The liquid from which the aerosol is generated is cooled so that thermophoresis can prevent agglomeration of the aerosol on the tube walls. To reduce the onset of phase separation in the final glassy oxide, it is important that each aerosol droplet contain all of the glass-forming elements of the core-doped glass.

© 1991 Optical Society of America