Spectroscopy and enhanced frequency upconversion in Nd³⁺–Yb³⁺codoped TPO glasses: energy transfer and NIR to visible upconverter

Abstract

TeO-PbO (TPO) glasses codoped with Nd and Yb ions have been fabricated by conventional melting technique. The absorption, emission and excitation spectra of the samples have been recorded. The optical band gap in both the doped/codoped glasses is found to be ∼3.31 eV. Judd-Ofelt analysis has been carried out by using the absorption spectrum of 0.8 mol% Nd doped glass to determine the radiative properties viz radiative transition probabilities, branching ratios, radiative lifetimes, quality factor and emission cross sections of some emitting levels for Nd ions. The radiative transition probability for the G → I transition (∼1926 Hz) is found to be maximum compared to other G → I (∼1622 Hz) and F → I (∼865 Hz) transitions. Upconversion (UC) luminescence of the samples has been examined by the 980 nm CW diode laser excitation. Effect of addition of Yb ions in the Nd doped glasses on UC emission intensity has been discussed. The UC emission intensity corresponding to the green, red and NIR bands in the codoped glass has been enhanced by ∼17, ∼12 and ∼42 times as compared to that of the Nd singly doped glass. The quantum efficiency for the G level is found to be ∼32%. The nephelauxetic ratio, bonding parameter and covalency of Nd ions have been found positive which represents the covalent bonding between Nd ion and oxygen atom. The colour tunability from yellowish-green to dominant green region has been obtained in the optimized codoped TPO glass.

Effect of the Addition of Pb3O4 and TiO2 on the Optical Properties of Er3+/Yb3+:TeO2–WO3 Glasses

“…The absorption coefficient (α), optical band gap ( E g ), and incident photon energy ( h ν) are correlated by a relation and are given by Tauc and Mott, 28,29 where, “ A ” represents the proportionality constant and “ r ” is used for a particular real number, such as, r = 1/2 and 3/2 for direct allowed and direct forbidden transitions, whereas r = 2 and 3 are used for indirect allowed and indirect forbidden transitions, respectively. 12 Therefore, to calculate the direct optical band gap in all the RE ion-doped/codoped glasses, r = 1/2 has been considered in eq 1. The curves between (α h ν) 2 versus incident radiation energy “hν (in eV)” for all the doped/codoped glasses are shown in Figure 2.…”

“…It means that the degree of structural compactness of the geometrical configuration of the glass matrix enhances on introducing the Pb 3 O 4 and TiO 2 HMO materials. 18 The RE ion concentration ( N RE ) and inter-ionic separation between RE ions ( R RE ) in all the prepared glasses have been calculated by using the following relations 12,18,33 where, “ N A ” is the Avogadro number (6.022 × 10 23 ). In the present case, the RE ion concentration and the inter-ionic separation almost remain the same.…”

Enhancement of Optical Emission and Dielectric Properties of Eu3+-Doped Na2O–ZnO–TeO2 Glass Material

“…The peak position of the transitions shifted towards a higher wavelength for 2% doping of concentration of Nd 2 O 3 . This shifting may be arises due to the presence of excited Nd 3+ ions in 2 D 5/2 and 4 G 11/2 state for the respective transitions with blue emissions [6].…”

“…Tellurite glasses doped with rare-earth ions have attracted researchers for their broad spectrum of applications in optoelectronic and photo-electronic devices viz solid-state lasers optical switches, broad-band amplifications, nonlinear optical devices, infra-red (NIR) laser windows, optical fibers. The doping of rare-earth ions in tellurite glasses have shown interesting properties like amplification of optical signal in the visible and NIR region, optical data storage, white light emission and planner waveguides which are applicable to micro-chip lasers, biomedical diagnostics, light-emitting diodes and high-density optical data reading [6][7][8]. Recently, the precise properties of tellurite glass have been investigated for the demonstration of various spectroscopic and nonlinear optical device applications as broadband light emission and optical communications network.…”

Preparation and photoluminescence enhancement of Au nanoparticles with ultra‐broad plasmonic absorption in glasses

“…Improving the UCL efficiency is still one of the urgent issues in this field. At present, a variety of methods such as tailoring the rare earth doping level, a host matrix selection with low phonon energy, photonic crystals surface effect have been developed to enhance the UCL . The collective oscillations of the free electrons of metal nanoparticles (NPs) can generate the localized plasmonic resonance absorption (LSPR), which offers another effective way to enhance the UCL efficiency of rare‐earth doped materials .…”