Optical spectra and luminescence dynamics of the Dy-doped Gd₂SiO₅ single crystal

Abstract

Spectroscopic properties of the Dy³⁺:Gd₂SiO₅ (GSO) single crystal were investigated. The polarized absorption and unpolarized emission spectra were measured at temperature ranging from 10 K to 300 K. Experimental oscillator strengths were determined from room temperature polarized absorption spectra and phenomenological intensity parameters Ω _t were calculated by using the standard Judd–Ofelt theory. Low-temperature measurements were used to determine the energy level structure of two nonequivalent Dy³⁺ sites in the GSO crystalline host. Analysis of spectra and decay curves of the ⁴F_9/2 emission revealed that Dy³⁺ ions entering nine-coordinated sites with C _3v symmetry and Dy³⁺ ions entering the seven-coordinated sites with C _s symmetry form two distinct, well-isolated subsystems weakly coupled by the spectral energy migration process. In addition to dissimilar crystal field splitting of multiplets, the two subsystems differ significantly in the efficiency of excitation energy transfer between dysprosium ions, thereby showing dissimilar self-quenching of the ⁴F_9/2 emission. Besides, only one of the two Dy³⁺ subsystems is coupled to Gd³⁺ ions by nonradiative Gd³⁺–Dy³⁺ energy transfer process. Laser potential related to the ⁴F_9/2→⁶H_13/2 yellow luminescence of dysprosium ions was assessed based on evaluation of the emission cross-section values. It was concluded that the Dy:Gd₂SiO₅ (Dy:GSO) is a promising material for the visible laser operation.