Spectroscopic investigations on Dy3+ ions doped zinc lead alumino borate glasses for photonic device applications

This paper presents the structural, optical absorption, photoluminescence (PL) and decay spectral properties of Dy³⁺ ions doped zinc lead alumino borate (ZPAB) glasses to elucidate their possible usage in photonic devices such as w-LEDs and lasers. A broad hump shown by the XRD spectrum recorded for an un-doped ZPAB glass confirms its non-crystalline nature. The Judd-Ofelt (J-O) intensity parameter evaluated from the measured oscillator strengths of the absorption spectral features were used to estimate various radiative parameters and also to understand the nature of bonding between Dy³⁺ ions and oxygen ligands. Under 350 nm excitation, the as-prepared glasses are exhibiting two emission bands ⁴F_9/2 → ⁶H_15/2 (blue), and ⁴F_9/2 → ⁶H_13/2 (yellow) at 483 and 575 nm, respectively. From the PL spectra, the Y/B ratio values, CIE chromaticity color coordinates and color correlated temperature (CCT) were evaluated. The experimental lifetimes measured from the decay profiles are decreasing with increase in Dy³⁺ ions concentration in these glasses which may be attributed to the cross-relaxation and non-radiative multiphonon relaxation process. Decay profiles observed for higher concentration were well fitted to Inokuti-Hirayama (I-H) model to understand the energy transfer process and subsequent decrease in experimental lifetimes. The higher values of radiative parameters, emission cross-sections, quantum efficiency, optical gain and gain band width suggest the suitability of 0.5 mol% of Dy³⁺ ions in these ZPAB glasses for the photonic device application.