Setsuhisa Tanabe

The Judd-Ofelt intensity parameters, ${\mathrm{\ensuremath{\Omega}}}_{\mathit{t}}$ (t=2,4,6) for f-f transitions of ${\mathrm{Er}}^{3+}$ ions doped in ${\mathrm{B}}_{2}$${\mathrm{O}}_{3}$-${\mathit{R}}_{2}$O (R=Na,K) glasses were determined from optical-absorption measurements, and their compositional dependence was investigated systematically. The values of ${\mathrm{\ensuremath{\Omega}}}_{2}$ exhibited a maximum around 25 mol % ${\mathit{R}}_{2}$O, while those of ${\mathrm{\ensuremath{\Omega}}

Rare-earth-doped optical amplifiers have a great potential for broadband Wavelength-Division-Multiplexed (WDM) telecommunication by tailoring host glass compositions. In order to design the emission spectra of doped rare-earth ions, it is important to understand the relationship between the local ligand field and various optical properties of specific 4f-levels, such as the radiative transition probability, the nonradiative decay probability, which dominate the spectral line width and quantum ef

The Ωt intensity parameters (t=2,4,6) of Er3+ ions in several oxide glasses and the isomer shift (IS) of 151Eu Mössbauer spectra in glasses of the same composition were determined. Among these Ωt’s, the Ω6 parameter was found to have a good relation with IS; Ω6 decreases with an increase of IS which reflects the 6s electron density of rare-earth ions. From the theoretical expression of Ωt, Ω6 is considered to be more affected by the overlap integrals of the 4f and 5d orbitals than Ω2 and Ω4, and

The upconversion properties of ${\mathrm{Er}}^{3+}$ ions were studied for the fluorophosphate glasses (45-x)${\mathrm{AlF}}_{3}$\ensuremath{\cdot}x${\mathrm{AlPO}}_{4}$\ensuremath{\cdot}${5\mathrm{E}\mathrm{r}\mathrm{F}}_{3}$\ensuremath{\cdot}${30\mathrm{C}\mathrm{a}\mathrm{F}}_{2}$\ensuremath{\cdot}${20\mathrm{B}\mathrm{a}\mathrm{F}}_{2}$, with use of the infrared radiation from a (Ga,Al)As laser diode (\ensuremath{\lambda}=802 nm) as an excitation source. Green upconversion fluorescence due to

Optical properties of the Ce:YAG glass-ceramic (GC) phosphor for the white LED were investigated. Concentration dependence of fluorescence intensity of Ce³⁺:5d→4f transition in the GC showed a maximum at 0.5mol%Ce₂O₃. Quantum efficiency (QE) of Ce³⁺ fluorescence in the GC materials, the color coordinate and luminous flux of electroluminescence of LED composite were evaluated with an integrating sphere. QE increased with increasing ceramming tempe

$^{151}\mathrm{Eu}$ M\"ossbauer effect measurements were carried out for various silicate and phosphate laser glasses doped with ${\mathrm{Eu}}^{3+}$ ions instead of ${\mathrm{Nd}}^{3+}$, for which Judd-Ofelt ${\mathrm{\ensuremath{\Omega}}}_{\mathit{t}}$ parameters are known. The isomer shift (IS) for the silicate glasses decreased with an increase in the electronegativity of the network-modifying alkali and alkaline-earth metal ions, indicating a decreased 6s electron density of the rare-earth

By utilizing efficient persistent energy transfer from Ce³⁺ to Er³⁺, we have successfully developed a novel garnet persistent phosphor of Y₃Al₂Ga₃O₁₂ doped with Er³⁺, Ce³⁺, Cr³⁺ ions (YAG<italic>G</italic>:Er–Ce–Cr) exhibiting long (&gt;10 h) near-infrared (NIR) persistent luminescence (PersL) in the broad range from 1450 nm to 1670 nm due to the typical Er³⁺:⁴I_13/2