Stimulated Emission Cross-section Σe Research Articles

Influence of rare earth substitution on structure, photoluminescence emission properties and Judd-Ofelt analysis of ZnS:Eu3+ red phosphors

A series of Eu3+ doped ZnS red emitting phosphors were synthesized by conventional low temperature solid state reaction technique. The structural and spectroscopic characteristics of the prepared materials were examined by theoretical and experimental methods. The XRD results confirm the formation of hexagonal structured ZnS material. Similar morphology is obtained from TEM and SEM analysis and the particle size and grain size were calculated. The compositional analysis using EDS confirms the atomic percentage present in the materials. The optical band gap energy of the samples varied from 3.59 to 3.43 eV. The PL emission under excitation 390 nm has greater emission intensity at concentration x = 0.1 in Zn(1-x)S: xEu3+ material. The intense red emission (614 nm) for concentration x = 0.1 have CIE coordinates (0.6090, 0.3905) with color purity 90.41% and CCT 1629.26 K. The site symmetry of Eu3+ ions was explained using PL emission spectra. The intensity parameters Ω2, Ω4 and Ω6, radiative properties like branching ratio (βR), transition radiative parameter (AR), stimulated emission cross section σe, radiative life time (τR) was calculated from Judd-Ofelt theory. The luminescence decay kinetics was analyzed and the life time of material was calculated in millisecond (ms) range. The strong and intense red emission and the improved stimulated emission cross section offer Eu3+ doped ZnS material useful for designing optoelectronic device applications.

Optical-transition properties of the Nd3+ ion in Gd0.8La0.2VO4 crystal

Nd:Gd 0.8 La 0.2 VO 4 has been investigated as a Nd-doped laser crystal belonging to the zircon structural family. The optical absorption and emission properties have been characterized for the Nd3+ ion in Nd:Gd0.8La0.2VO4 crystal. It results in a good fit when the Judd–Ofelt theory of parity-forbidden electric-dipole transitions of rare earth ions on noncentrosymmetric sites is applied to the crystal. Based on the Judd–Ofelt theory, the following spectral parameters have been obtained: the phenomenological parameters Ωt (t=2, 4, and 6), the radiative lifetime, the fluorescence branching ratios and the quantum efficiency. The stimulated emission cross section σe for the 1.06 μm transition of Nd3+ in the crystal has been determined from fluorescence measurements. In comparison with those of other laser crystals, these results indicated that Nd:Gd0.8La0.2VO4 is a promising efficient laser material.