Evidence of the influence of phonon density on Tm3+ upconversion luminescence in tellurite and germanate glasses

Abstract

Spectral properties of blue upconversion luminescences in Tm 3ϩ doped tellurite ͑PWT, PbF 2 -WO 3 -TeO 2 ͒ glasses and germanate ͑PWG, PbF 2 -WO 3 -GeO 2 ͒ glasses pumped by a tunable dye laser were studied at room temperature. Two emission bands centered at 453 and 477 nm, corresponding to the 1 D 2 → 3 H 4 and 1 G 4 → 3 H 6 transitions of Tm 3ϩ ions respectively, were observed. The two-photon absorption mechanism responsible for the 477 nm luminescence was confirmed by a quadratic dependence of luminescent intensities on the excitation power. Tellurite glasses showed a weaker upconversion luminescence than germanate glasses. This observation was inconsistent with the prediction from the phonon sideband measurement. In this article, Raman spectroscopy and transmittance measurement were employed to investigate the origin of the difference in upconversion luminescences in the two glasses. Compared with phonon sideband spectroscopy, Raman spectroscopy extracts more information, including both phonon energy and phonon density, and therefore, is a more effective analytical tool for understanding upconversion luminescence. Our results showed that the phonon energy as well as phonon density of the host glass is important in determining the upconversion efficiency.

Spectroscopic properties of GeO2- and Nb2O5-modified tellurite glasses doped with Er3+

“…The red intensity is not affected apparently by the concentration of GeO 2 or Nb 2 O 5 . The green luminescence intensity is mainly determined by the MPE [17] of glass hosts, while the red upconversion emission intensity is mainly determined by ESA procedure [18]. Our investigation indicates that the MPE of host glass might be improved with increasing Nb 2 O 5 or GeO 2 content, which results in the promotion of the multi-phonon relaxation rate and decrease the upconversion emissions.…”

Spectroscopic properties of Er3+-doped and Er3+/Yb3+-codoped PbF2–MOx (M=Te, Ge, B) oxyfluoride glasses

“…In recent years, the upconversion process of rare-earth ions under infrared laser diode (LD) excitation in transparent hosts has been studied extensively due to potential applications in the fields such as 3D display, optical data storage, under-sea optical communications, biomedical diagnostics, sensors as well as room temperature infrared pumped visible lasers [1][2][3][4][5][6]. It is well known that Er 3+ is the most commonly used as an activator among the rare-earth ions [1][2][3][4][7][8][9][10][11][12][13].…”

Upconversion luminescence of Tm3+ and Yb3+-codoped lutetium oxide nanopowders

“…Solid-state lasers operating at visible wavelengths have attracted much interest for their wide applications such as highdensity optical data storage, undersea communication, medicine and color displays [1][2][3][4]. The rapid development and commercial availability of high power semiconductor lasers allows constructing upconversion lasers for the visible spectral range.…”