Aluminum or phosphorus co-doping effects on the fluorescence and structural properties of neodymium-doped silica glass

Abstract

To utilize the excellent properties of silica (SiO2) glass for a glass laser host, neodymium-aluminum (Nd–Al) and neodymium-phosphorous (Nd–P) co-doped SiO2 glasses were studied. They were prepared by plasma-torch chemical vapor deposition (CVD). It was found that a doping level less than ten times the number of Nd for the Al co-dopant and less than about fifteen times for the P co-dopant was enough to remove undesirable fluorescence properties of Nd-doped SiO2 glasses and make them suitable for laser application. The clustering Nd ions disperse well in a glass matrix and lasing fluorescence increases. The effects of the Al dopant on the density and Raman spectra were also studied to obtain structural information. On the basis of glass science and solution chemistry, the marked effects of both dopants were explained by the following model. Nd ions can be well incorporated into a SiO2 glass network through co-dopant oxide forming a solvation shell around the Nd ions. This model leads to an expansible method for coordination control around active ions in SiO2 glass. A preliminary experiment on laser oscillation using Nd–Al co-doped SiO2 glass was also carried out.

Chromium-doped silica optical fibres: influence of the core composition on the Cr oxidation states and crystal field

“…The distortion of the perfect tetrahedral symetry partially lifts the degeneracy of some energy levels such as 3 T 1 ( 3 F) and causes the presence of several peaks assigned to one transition. The Cr(Al) absorption spectrum is similar to those observed in aluminate [7] and alumino-silicate glasses [8] [18,19].…”

Cosolvent-free sol–gel synthesis of rare-earth and aluminum codoped monolithic silica glasses

“…The¸e xp value of the Al-codoped glass is much larger than that of the Al-free glass because of the enhanced dispersion of Nd 3+ ions, resulting in a relatively large¯value (³0.30.4). However, thȩ exp value is not large enough, as compared with PL decay constants reported for NdAl codoped glasses (280450, 3), 4) 257425, 7) 250550, 12) 325, 14) 240250, 17) and 376¯s 27) ). It is partly because of the small z Al /z Nd value (z Al /z Nd = 1).…”

“…Most of ), which commonly accelerate the nonradiative transition of PL centers. In Nd-doped silica glasses, PL decay constants as large as ³400 500¯s have been realized by hydrogen-free synthesis using the plasma CVD technique, 4) and by HD isotope exchange of SiOH groups to decrease the phonon energy of the relevant stretching mode.…”

Doping effects in amorphous oxides

“…The reason had remained unclear for a decade. In 1980s, Arai et al 52) measured the density of NdAl-codoped silica glasses, and found that Nd Al codoping brought about a negative volume change on mixing. This result indicated that in some manner, the Nd 3+ ion and the Al 3+ ion are correlated with each other in a silica network.…”