2.7 µm Mid‐Infrared Emission in Highly Erbium‐Doped Lanthanum Gallate Glasses Prepared Via an Aerodynamic Levitation Technique

Abstract

AbstractHighly Er3+‐doped La2O3–Ga2O3 glasses up to ≈5.85 × 1021 cm−3 in Er3+ concentration are synthesized by an aerodynamic levitation technique. The glasses are characterized by high glass‐transition temperatures, low OH− absorptions, and long infrared cut‐off wavelengths. Judd–Ofelt analysis reveals a large radiative transition rate and a high branching ratio of the 4I11/2 → 4I13/2 transition, e.g., 46 s−1 and 21%, respectively, at 10 mol% Er2O3. The intensity of 2.7 µm emission drastically increases with increasing Er2O3 content and reaches a maximum at 10 mol% Er2O3. By contrast, the intensity of the 1.5 µm emission decreases with increasing Er2O3 content when the Er2O3 content is greater than 1 mol%. The emission cross‐section and the gain bandwidth at 2.7 µm are as large as 9.05 × 10−21 cm2 and 9.19 × 10−26 cm3 at 10 mol% Er2O3, respectively. The upconversion spectra also indicate that the investigated glasses exhibit small multiphonon relaxation rates and large quenching concentrations.