Achieving narrow bandwidth and high stimulated cross-section in Nd3+-doped LiCaB glasses for near infra-red laser amplifiers

The aim of this research is to examine the effects of Nd3+ ions on the spectroscopic characteristics of different concentrations of lithium-calcium-borate glasses and improve the emission cross section alongside bandwidth. The prepared glasses were produced with the melt-quenching technique and were thoroughly analyzed to determine their usefulness as laser amplifiers. Various studies were conducted, including X-ray diffraction (XRD), solid-state nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), absorption and emission measurements, and time decay curve measurements. The structural analysis using XRD and NMR techniques revealed that the glasses were amorphous and that non-bridging oxygen was present. Moreover, it was discovered that the glass-forming tendency and glass stability of these glasses improved with the concentration of Nd3+ ions. The glasses' absorption spectra display 10 transition states in UV and visible regions. Among all the prepared glasses, the lithium-calcium-borate glass doped with 0.5 mol % Nd3+ ions stand out with a stimulated emission cross-section value of 3.40 x 10-20 cm2 and a narrow bandwidth of 33 nm, making it an ideal lasing amplifier medium due to the 4F3/2 -> 4I11/2 (1060 nm) transition. Theoretical Judd-Ofelt calculations were conducted to evaluate various parameters, including oscillatory strength, radiative parameters, radiative lifetime, gain bandwidth, figure-of-merit, and saturation current, for all transitions in the near-infrared region, to support the experimental investigations and offer a detailed discussion of these parameters.