Search for: All records

A comparative spectroscopic investigation was conducted to evaluate the potential of Dy³⁺and Er³⁺doped Ga₂Ge₅S₁₃chalcogenide glass and CsCdCl3 crystal for suitability as gain media for mid-infrared lasers operating within the 4.1-4.8 (m spectral range. Both rare-earth ions exhibited broad mid-IR emissions at room temperature centered at ∼4.4-4.5 µm, attributed to the Dy³⁺:⁶H_11/2→⁶H_13/2and Er³⁺:⁴I_9/2→⁴I_11/2transitions. The fluorescence lifetimes of these mid-IR transitions varied significantly between these two host materials. Dy³⁺and Er³⁺doped CsCdCl₃crystals exhibited long lifetimes of ∼9-12 ms, while the same ions in Ga₂Ge₅S₁₃glass yielded lifetimes in the range of ∼1 ms. Temperature-dependent lifetime measurements further confirmed the role of multiphonon relaxation in Dy³⁺: Ga₂Ge₅S₁₃, although fitting with the temperature dependence of the multiphonon energy-gap law indicated the presence of additional nonradiative decay channels, likely involving impurity interactions. In contrast, Er³⁺emissions exhibited minimal temperature dependence across both hosts, with measured lifetimes closely matching calculated radiative values. Judd-Ofelt analyses revealed radiative properties and transition probabilities comparable to other low-maximum-phonon-energy rare-earth-doped hosts, with the studied Dy³⁺doped host materials standing out by offering sigma-tau products several times higher than those of Er³⁺in the same hosts. 

A comparative study was conducted to investigate the 3.9 µm mid-IR emission properties of Ho³⁺doped NaYF₄and CsCdCl₃crystals as well as Ho³⁺doped Ga₂Ge₅S₁₃glass. Following optical excitation at ∼890 nm, all the studied materials exhibited broad mid-IR emissions centered at ∼3.9 µm at room temperature. The mid-IR emission at 3.9 µm, originating from the⁵I₅→⁵I₆transition, showed long emission lifetime values of ∼16.5 ms and ∼1.61 ms for Ho³⁺doped CsCdCl₃crystal and Ga₂Ge₅S₁₃glass, respectively. Conversely, the Ho³⁺doped NaYF₄crystal exhibited a relatively short lifetime of ∼120 µs. Temperature dependent decay time measurements were performed for the⁵I₅excited state for all three samples. The results showed that the emission lifetimes of Ho³⁺:CsCdCl₃and Ho³⁺:Ga₂Ge₅S₁₃were nearly temperature independent over the range studied, while significant emission quenching of the⁵I₅level was observed in Ho³⁺:NaYF₄. The temperature dependence of the multi-phonon relaxation rate for 3.9 µm mid-IR emission in Ho³⁺:NaYF₄crystal was determined. The room temperature stimulated emission cross-sections for all three samples were calculated using the Füchtbauer-Landenburg equation. Furthermore, the results of Judd-Ofelt analysis are presented and discussed. 

The mid-IR spectroscopic properties of ${\mathrm{E}\mathrm{r}}^{3+}$doped low-phonon ${\mathrm{C}\mathrm{s}\mathrm{C}\mathrm{d}\mathrm{C}\mathrm{l}}_3$and ${\mathrm{C}\mathrm{s}\mathrm{P}\mathrm{b}\mathrm{C}\mathrm{l}}_3$crystals grown by the Bridgman technique have been investigated. Using optical excitations at $\sim <\#comment/>800\mathrm{n}\mathrm{m}$and $\sim <\#comment/>660\mathrm{n}\mathrm{m}$, both crystals exhibited IR emissions at $\sim <\#comment/>1.55$, $\sim <\#comment/>2.75$, $\sim <\#comment/>3.5$, and $\sim <\#comment/>4.5\text{µ<\#comment/>}\mathrm{m}$at room temperature. The mid-IR emission at 4.5 µm, originating from the ${}^4{\mathrm{I}}_{9/2}\to <\#comment/>{}^4{\mathrm{I}}_{11/2}$transition, showed a long emission lifetime of $\sim <\#comment/>11.6\mathrm{m}\mathrm{s}$for ${\mathrm{E}\mathrm{r}}^{3+}$doped ${\mathrm{C}\mathrm{s}\mathrm{C}\mathrm{d}\mathrm{C}\mathrm{l}}_3$, whereas ${\mathrm{E}\mathrm{r}}^{3+}$doped ${\mathrm{C}\mathrm{s}\mathrm{P}\mathrm{b}\mathrm{C}\mathrm{l}}_3$exhibited a shorter lifetime of $\sim <\#comment/>1.8\mathrm{m}\mathrm{s}$. The measured emission lifetimes of the ${}^4{\mathrm{I}}_{9/2}$state were nearly independent of the temperature, indicating a negligibly small nonradiative decay rate through multiphonon relaxation, as predicted by the energy-gap law for low-maximum-phonon energy hosts. The room temperature stimulated emission cross sections for the ${}^4{\mathrm{I}}_{9/2}\to <\#comment/>{}^4{\mathrm{I}}_{11/2}$transition in ${\mathrm{E}\mathrm{r}}^{3+}$doped ${\mathrm{C}\mathrm{s}\mathrm{C}\mathrm{d}\mathrm{C}\mathrm{l}}_3$and ${\mathrm{C}\mathrm{s}\mathrm{P}\mathrm{b}\mathrm{C}\mathrm{l}}_3$were determined to be $\sim <\#comment/>0.14\times <\#comment/>{10}^{-<\#comment/>20}{\mathrm{c}\mathrm{m}}^2$and $\sim <\#comment/>0.41\times <\#comment/>{10}^{-<\#comment/>20}{\mathrm{c}\mathrm{m}}^2$, respectively. The results of Judd–Ofelt analysis are presented and discussed.