Spectroscopic and laser properties of Sm³⁺ ions doped lithium fluoroborate glasses for efficient visible lasers

Spectroscopic properties of Sm3+ ions doped Alkaliborate glasses for photonics applications

A new series of Sm³⁺ doped alkaliborate glasses have been prepared by melt quenching technique and their structural and spectroscopic properties were analysed employing XRD, FTIR, optical absorption, photoluminescence and decay spectral measurements in order to explore their suitability for photonic applications. The amorphous nature have been confirmed through XRD analysis and the FTIR spectra reveal the presence of fundamental stretching and bending vibrations of the borate networks in the prepared glasses. From the absorption peak positions, bonding parameter (δ) values were calculated to examine the nature of the metal-ligand bond. The optical band gap (E_opt) corresponds to the direct and indirect allowed transitions and the Urbach energies (ΔE) were calculated from the absorption spectra to understand the electronic band structure of the studied glasses. The Judd-Ofelt (JO) intensity parameters Ω_λ (λ=2, 4 and 6) were determined to explore the symmetry of the ligand environment around the Sm³⁺ ions in the studied glasses. The luminescence spectra exhibit four emission bands in the visible region due to the ⁴G_5/2→⁶H_5/2, ⁶H_7/2, ⁶H_9/2 and ⁶H_11/2 transitions. The radiative parameters such as transition probability (A), stimulated emission cross-section (σ_P^E), branching ratios (β_R) and radiative lifetime (τ_R) have been determined from the luminescence spectra using JO theory to ensure the suitability of the studied glasses for optoelectronic applications. The luminescence spectra were characterized through CIE 1931 chromaticity diagram to examine the dominant emission color of the studied glasses. The lifetime values of the Sm³⁺ doped studied glasses pertaining to the ⁴G_5/2 excited level have been determined through decay curve measurements and the non-exponential decay curves were fitted to the Inokuti-Hirayama model to analyze the energy transfer mechanism between the nearby Sm³⁺ ions. The obtained results were discussed and compared with the similar reported glasses.