Fluorescence and its Nd3+ Concentration Dependence of Nd-Doped SiO2 Glasses Prepared by Plasma Torch CVD

Abstract

The time resolved fluorescence spectra and their Nd³⁺ concentration C_Nd dependence were observed in Nd-doped SiO₂ glasses prepared by plasma torch CVD. The ⁴F_3/2 radiative emissions observed consist of a fast (FDC, τ_m≃0.35 µs) and a slow (SDC, τ_m≃470 µs) decay component. The FDC are characterized by the intensity ratio (⁴F_3/2–⁴I_11/2/⁴F_3/2–⁴I_9/2>1), but the SDC by the inverse ratio and the spectral shift to the longer wavelength. The SDC increases and reaches almost constant values in higher C_Nd. The FDC can not be observed in very low C_Nd region, but increases abraptly in higher C_Nd. The FDC is ascribed to the Nd³⁺ in the clustering microstructure and the SDC is ascribed to the isolated Nd³⁺ in crystal field unique to unitary SiO₂ glass.