Photoluminescence properties of Bi/Al-codoped silica optical fiber based on atomic layer deposition method

Abstract

The Bi/Al-codoped silica optical fibers are fabricated by atomic layer deposition (ALD) doping technique combing with conventional modified chemical vapor deposition (MCVD) process. Bi2O3 and Al2O3 are induced into silica optical fiber core layer by ALD technique, with Bis (2,2,6,6-tetra-methyl-3,5-heptanedionato) Bismuth(III) (Bi(thd)3) and H2O as Bi and O precursors, and with Al(CH3)3 (TMA) as Al precursor, respectively. The structure features and optical properties of Bi/Al-codoped silica optical fibers are investigated. Bi2O3 stoichiometry is confirmed by X-ray photoelectron spectroscopy (XPS). The valence state of Bi element is +3. Concentration distribution of Si, Ge and O elements is approximately 24–33, 9 and 66mol%, respectively, in fiber preform core and cladding layer region. Bi and Al ions have been also slightly doped approximately 150–180 and 350–750ppm in fiber preform core, respectively. Refractive index difference of the Bi/Al-codoped fiber is approximately 0.58% using optical fiber refractive index profiler analyzer. There are obvious Bi-type ions absorption peaks at 520, 700 and 800nm. The fluorescence peaks are at 1130 and 1145nm with 489 and 705nm excitations, respectively. Their fluorescence lifetimes are 701 and 721μs, respectively. And then there are obvious fluorescence bands in 600–850 and 900–1650nm with 532nm pump exciting. There is a maximum fluorescence intensity peak at 1120nm, and its full wave at half maximum (FWHM) is approximately 180nm. These may mainly result from the interaction between Bi and Al ions. The Bi/Al-codoped silica optical fibers would be used in high power or broadly tunable laser sources, and optical fiber amplifier in the optical communication fields.