Optical transitions and visible upconversion in Er3+ doped niobic tellurite glass

TLDR

Visible upconversion fluorescence in Er³⁺‑doped niobic tellurite glass offers potential for color displays, underwater communication, and infrared sensing. Er³⁺‑doped Nb₂O₅–TeO₂ glass was fabricated and characterized as a candidate for optical fiber lasers and amplifiers. The glass exhibits intense, broad 1.53 µm infrared fluorescence (51 nm FWHM, 2.6 ms lifetime, ~100 % quantum efficiency, 8.52×10⁻²¹ cm² emission cross‑section) and efficient visible upconversion (531, 553, 670 nm) under 975 nm and 798 nm excitation, with a green‑upconversion efficiency of 9.5×10⁻⁴ comparable to Er/Yb‑codoped fluoride glasses.

Abstract

Er 3+ doped Nb2O5–TeO2 (NT) glass suitable for developing optical fiber laser and amplifier has been fabricated and characterized. Intense and broad 1.53 μm infrared fluorescence and visible upconversion luminescence were observed under 975 nm diode laser and 798 nm laser excitation. For 1.53 μm emission band, the full width at half-maximum is 51 nm, the fluorescence lifetime is 2.6 ms, and the quantum efficiency is ∼100%. The maximum emission cross section is 8.52×10−21 cm2 at 1.532 μm, and is higher than the values in silicon and phosphate glasses. Under 798 nm excitation, efficient 531, 553, and 670 nm upconversion emissions are due to two-photon absorption processes. The “standardized” efficiency for the green upconversion light is 9.5×10−4, and this value is comparable to that reported for Er3+/Yb3+ codoped fluoride glasses. Intense visible upconversion fluorescence in Er3+ doped NT glass can be used in color display, undersea communication, and infrared sensor.