Visible emission studies of melt-grown Dy-doped CsPbCl₃ and KPb₂Cl₅ crystals

We report results of the optical properties of Dy-doped CsPbCl₃ and KPb₂Cl₅ bulk crystals for potential applications in yellow solid-state laser development. The crystals were synthesized from purified starting materials and melt-grown by vertical Bridgman technique. Optical transmission measurements revealed characteristic absorption bands from intra-4f transitions of Dy³⁺ ions. Direct optical excitation at 455 nm (⁶H_15/2 → ⁴I_15/2) resulted in dominant yellow emission bands at ∼575 nm from the ⁴F_9/2 excited state of Dy³⁺ ions. In addition, both crystals exhibited weaker emission lines in the blue (∼483 nm) and red (∼670 nm) regions. The peak emission-cross sections for the yellow transition (⁴F_9/2 → ⁶H_13/2) were determined to be ∼0.22 × 10⁻²⁰ cm² for Dy: CsPbCl₃ (λ_peak = 576.5 nm) and ∼0.59 × 10⁻²⁰ cm² for Dy: KPb₂Cl₅ (λ_peak = 574.5 nm). The spectral properties and decay dynamics of the ⁴F_9/2 excited state were evaluated within the Judd-Ofelt theory to predict total radiative decay rates, branching ratios, and emission quantum efficiencies.