Structure, optical properties and energy transfer analysis of Nd3+, Dy3+ co-doped CeF3 crystal for potential laser application

Abstract

A crack-free Nd³⁺, Dy³⁺ co-doped CeF₃ single crystal was synthesized through the Bridgman method, and a thorough investigation of its crystal structure and optical properties was conducted. The analysis of energy transfer processes between Nd³⁺ and Dy³⁺ was conducted as well. The XRD pattern shows that Nd,Dy:CeF₃ was crystallized in the hexagonal system and the calculated lattice parameters of the as-grown crystal are a = 7.1161 Å and c = 7.2708 Å. Through the absorption spectrum, J–O theory calculation was carried out, and results show that the radiative lifetimes of Nd³⁺:⁴F_3/2 and Dy³⁺:⁴F_9/2 levels in the Nd,Dy:CeF₃ crystal are 189.93 μs and 989.61 μs, respectively. The maximum emission cross-sections of the Nd³⁺:⁴F_3/2 → ⁴I_11/2 transition and Dy³⁺:⁴F_9/2 → ⁶H_13/2 transition are 2.23 × 10⁻²⁰ cm² and 0.30 × 10⁻²⁰ cm² in the crystal. The fluorescence lifetimes of Nd³⁺:⁴F_3/2 and Dy³⁺:⁴F_9/2 levels are 104.00 μs and 298.03 μs, respectively. The laser induced damage threshold of the Nd,Dy:CeF₃ crystal is estimated to be 31.63 J cm⁻² through a single pulsed laser system (pumping wavelength: 1064 nm; pulse width: 9 ns). The analysis of energy transfer between Nd³⁺ and Dy³⁺ reveals that a large portion of energy transfers from Nd³⁺ to Dy³⁺ and then utilized by Dy³⁺ for IR fluorescence emission; thus, the emission cross-section of the band around 1.3 μm is enhanced. These results indicate that the Nd,Dy:CeF₃ crystal is a potential material for IR laser operation.