A New Sol–Gel Material Doped with an Erbium Complex and Its Potential Optical‐Amplification Application

The crystal structure of a ternary Er(DBM)₃phen complex (DBM = dibenzoylmethane; phen = 1,10‐phenanthroline) and its in‐situ synthesis via a sol–gel process are reported. The infrared (IR), diffuse reflectance (DR), and fluorescence spectra of the pure complex and the Er³⁺/DBM/phen co‐doped luminescent hybrid gel, formed via an in‐situ method (ErDP gel), have been investigated. The results reveal that the erbium complex is successfully synthesized in situ in the ErDP gel. Excitation at the maximum absorption wavelength of the ligands resulted in the typical near‐IR luminescence (centered at around 1.54 μm) resulting from the ⁴I_13/2 → ⁴I_15/2 transition of the Er³⁺ ion, which contributes to the efficient energy transfer from the ligands to the Er³⁺ ion in both the Er(DBM)₃phen complex and the ErDP gel (an antenna effect). The full width at half maximum (FWHM) centered at 1541 nm in the emission spectrum of the ErDP gel is 72 nm, which has potential for optical‐amplification applications. Further theoretical analysis on the Er³⁺ ion in the ErDP gel shows that it appears to be a promising candidate for tunable lasers and planar optical amplifiers.     

ErIII‐Cored Complexes Based on Dendritic PtII–Porphyrin Ligands: Synthesis,Near‐IR Emission Enhancement,and Photophysical Studies

A series of stable and inert complexes with Er^III cores and dendritic Pt^II‐porphyrin ligands exhibit strong near‐IR (NIR) emission bands via highly efficient energy transfer from the excited triplet state of the Pt^II‐porphyrin ligand to Er³⁺ ions. The NIR emission intensity of thin films of Er^III complexes at 1530 nm, originating from 4f–4f electronic transitions from the first excited state (⁴I_13/2) to the ground state (⁴I_15/2) of the Er³⁺ ion, is dramatically enhanced upon increasing the generation number (n) of the aryl ether dendrons because of site‐isolation and light‐harvesting (LH) effects. Attempts are made to distinguish the site‐isolation effect from the LH effect in these complexes. Surprisingly, the site‐isolation effect is dominant over the LH effect in the Er³⁺‐[Gn‐PtP]₃(terpy) (terpy: 2,2′:6′,2″‐terpyridine) series of complexes, even though the present dendrimer systems with Er^III cores have a proper cascade‐type energy gradient. This might be due to the low quantum yield of the aryl ether dendrons. Thus, the NIR emission intensity of Er³⁺‐[G3‐PtP]₃(terpy) is 30 times stronger than that of Er³⁺‐[G1‐PtP]₃(terpy). The energy transfer efficiency between the Pt^II‐porphyrin moiety in the dendritic Pt^II‐porphyrin ligands and the Ln³⁺ ion increases with increasing generation number of the dendrons from 12–43 %. The time‐resolved luminescence spectra in the NIR region show monoexponential decays with a luminescence lifetime of 0.98 μs for Er³⁺‐[G1‐PtP]₃(terpy), 1.64 μs for Er³⁺‐[G2‐PtP]₃(terpy), and 6.85 μs for Er³⁺‐[G3‐PtP]₃(terpy) in thin films of these complexes. All the Er^III‐cored dendrimer complexes exhibit excellent thermal stability and photostability, and possess good solubility in common organic solvents.     

Annealing studies of photoluminescence spectra from multiple Er3+ centers in er-implanted GaN

A study of selectively excited photoluminescence (PL) at ∼ 6K in Er-im planted GaN as a function of annealing temperature (400–1000°C) has detected nine different Er³⁺ centers with distinct ∼ 1540 nm ⁴I_13/2 → ⁴I_15/2 Er³⁺ PL spectra and different activation temperatures. However, most of the optically active implanted Er atoms are incorporated at annealing temperatures as low as 400°C on a single type of center for which PL can only be excited efficiently by direct intra-4f shell absorption and is not strongly pumped by either above-gap or broad-band below-gap absorption. This strongly suggests that this high-concentration Er³⁺ center is an isolated, isoelectronic center consistent with Er³⁺ substituted on a Ga site. In contrast, a very small fraction of the Er atoms that form a variety of Er-defect/impurity complexes dominate the Er³⁺ emission spectra excited by above-gap and broad-band below-gap absorption because of their larger cross sections for both carrier capture and optical absorption.     

Origin of photoluminescence from Er3+ centers in erbium doped GaAs and Al0.4Ga0.6 As grown by MBE

Sharp erbium-related intra-4f shell luminescence from Er doped GaAs and Al_0.4Ga_0.6 As epitaxial layers grown by molecular beam epitaxy (MBE) is presented. The emission arising from the two Er³⁺ excited states,⁴I_13/2 and⁴I_11/2 are studied. We have observed, by means of heat treatment under differentambients such as As, Ga and Al over pressure, that the optically active Er³⁺ preferentially occupies a Column III lattice site or Column III related defects. The photoluminescence results of co-doping Al_0.4Ga_0.6As:Er with Si and Be by MBE is also reported for the first time. A strong single 1.54 μm spontaneous emission line is achieved by co-doping with Be (≈1×10¹⁸ cm⁻³). This improvement is a result of successfully eliminating or suppressing the other transitions without sacrificing the 1.54 μm emission intensity or linewidth.     

Improvement of 1.53 μm emission and energy transfer of Yb3+/Er3+ co-doped tellurite glass and fiber

To improve the 1.53 μm band emission of Er³⁺, the trivalent Yb³⁺ ions were introduced into the Er³⁺ single-doped tellurite glass with composition of TeO₂–ZnO–La₂O₃, a potential gain medium for Er³⁺-doped fiber amplifier (EDFA). The improved effects were investigated from the measured 1.53 μm band and visible band spontaneous emission spectra together with the calculated 1.53 μm band stimulated emission (signal gain) spectra under the excitation of 975 nm laser diode (LD). It was found that Yb³⁺/Er³⁺ co-doping scheme can remarkably improve the visible band up-conversion and the 1.53 μm band fluorescence emission intensity, and meanwhile improves the 1.53 μm band signal gain to some extent, which were attributed to the result of the effective energy transfer of Yb³⁺:²F_5/2 + Er³⁺:⁴I_15/2 → Yb³⁺:²F_7/2 + Er³⁺:⁴I_11/2. The quantitative study of energy transfer mechanism was performed and microscopic energy transfer parameters between the doped rare-earth ions were determined. In addition, the spectroscopic properties of Er³⁺ were also investigated from the measured absorption spectrum according to the Judd–Ofelt theory, and the structure behavior and thermal stability of the prepared tellurite glass were analyzed based on the X-ray diffraction (XRD) and differential scanning calorimeter (DSC) measurements, respectively.     

Pr3+‐ and Pr3+/Er3+‐Doped Selenide Glasses for Potential 1.6 μm Optical Amplifier Materials

1.6 µm emission originated from Pr³⁺: (³F₃, ³F₄) → ³H₄ transition in Pr³⁺‐ and Pr³⁺/Er³⁺‐doped selenide glasses was investigated under an optical pump of a conventional 1480 nm laser diode. The measured peak wavelength and full‐width at half‐maximum of the fluorescent emission are ~1650 nm and ~120 nm, respectively. A moderate lifetime of the thermally coupled upper manifolds of ~212 ± 10 µs together with a high stimulated emission cross‐section of ~(3 ± 1)×10^??20 cm² promises to be useful for 1.6 µm band fiber‐optic amplifiers that can be pumped with an existing high‐power 1480 nm laser diode. Codoping Er³⁺ enhances the emission intensity by way of a nonradiative Er³+: ⁴I_{13/2 →} Pr³⁺: (³F₃, ³F₄) energy transfer. The Dexter model based on the spectral overlap between donor emission and acceptor absorption describes well the energy transfer from Er³⁺ to Pr³⁺ in these glasses. Also discussed in this paper are major transmission loss mechanisms of a selenide glass optical fiber.     

Giant Red-Shifted Emission in (Sr,Ba)Y2O4:Eu2+ Phosphor Toward Broadband Near-Infrared Luminescence

Near-infrared (NIR) light-emitting diodes (LEDs) light sources are desirable in photonic, optoelectronic, and biological applications. However, developing broadband red and NIR-emitting phosphors with good thermal stability is always a challenge. Herein, the synthesis of Eu²⁺-activated SrY₂O₄ red phosphor with high photoluminescence quantum efficiency and broad emission band ranging from 540 to 770 nm and peaking at 620 nm under 450 nm excitation is designed. Sr/Ba substitution in SrY₂O₄:Eu²⁺ has been further utilized to achieve tunable emission by modifying the local environment, which facilitates the giant red-shifted emission from 620 to 773 nm while maintaining the outstanding thermal stability of SrY₂O₄:Eu²⁺. The NIR emission is attributed to the enhanced Stokes shift and crystal field strength originated from the local structural distortions of [Y1/Eu1O₆] and [Y2/Eu2O₆]. The investigation in charge distribution around Y/Eu provides additional insight into increasing covalency to tune the emission toward the NIR region. As-fabricated NIR phosphor-converted LEDs demonstration shows its potential in night-vision technologies. This study reveals the NIR luminescence mechanism of Eu²⁺ in oxide-based hosts and provides a design principle for exploiting Eu²⁺-doped NIR phosphors with good thermal stability.     

Er3+–Tm3+ co-doped tellurite fibers for broadband optical fiber amplifier around 1550 nm band

Tellurite fibers with 7500 ppm Er³⁺ concentration and diverse 2500–15,000 ppm Tm³⁺ concentrations were manufactured, and their amplified spontaneous emission (ASE) intensities 1550 nm band around were obtained for 980 and 790 nm pump laser. Maxima 187 nm bandwidth at −3 dB points using Er³⁺–Tm³⁺ co-doped tellurite optical fibers pumping at 790 nm was obtained, and energy transfer (ET) process between ⁴I_13/2 Er³⁺ and ³F₄ Tm³⁺ levels related with the amplifier quantum efficiency was studied from experimental and calculated lifetime.     

Luminescence and microstructure of Er/O co-doped Si structures grown by MBE using Er and SiO evaporation

Er and O co-doped Si structures have been prepared using molecular-beam epitaxy (MBE) with fluxes of Er and O obtained from Er and silicon monoxide (SiO) evaporation in high-temperature cells. The incorporation of Er and O has been studied for concentrations of up to 2×10²⁰ and 1×10²¹ cm⁻³, respectively. Surface segregation of Er can take place, but with O co-doping the segregation is suppressed and Er-doped layers without any indication of surface segregation can be prepared. Si_1−xGe_x and Si_1−yC_y layers doped with Er/O during growth at different substrate temperatures show more defects than corresponding Si layers. Strong emission at 1.54 μm associated with the intra-4f transition of Er³⁺ ions is observed in electroluminescence (EL) at room temperature in reverse-biased p–i–n-junctions. To optimize the EL intensity we have varied the Er/O ratio and the temperature during growth of the Er/O-doped layer. Using an Er-concentration of around 1×10²⁰ cm⁻³ we find that Er/O ratios of 1 : 2 or 1 : 4 give higher intensity than 1 : 1 while the stability with respect to breakdown is reduced for the highest used O concentrations. For increasing growth temperatures in the range 400–575°C there is an increase in the EL intensity. A positive effect of post-annealing on the photoluminescence intensity has also been observed.     

Phase relations in Cu- RO1.5- O (R < Ho,Er, Yb) and gibbs energy of formation of Cu2R2O5 (R < Ho,Er, Yb) between 1000 and 1325K

Phase relations in Cu-RO_1.5-O(R < Ho,Er,Yb) ternary systems at 1273K have been established by isothermal equilibration of samples containing different ratios of Cu:R(R < Ho,Er,Yb) in flowing air or high purity argon atmosphere for four days. The samples were then rapidly cooled to ambient temperature and the coexisting phases were identified by powder x-ray diffraction analysis. Only one ternary oxide, Cu₂R₂O₅(R < Ho,Er,Yb) was found to be stable. The chemical potential of oxygen for the coexistence of the three phase assemblage, Cu₂O + R₂O₃ + Cu₂R₂O₅(R < Ho,Er,Yb) has been measured by employing the solid-state galvanic cells,< (−) Pt, Cu₂O + Ho₂O₃+ Cu₂Ho₂O₅//CSZ//Air (Po₂< 2.12 × 10⁴ Pa), Pt (+) (−) Pt, Cu₂O + Er₂O₃+ Cu₂Er₂O//CSZ//Air (Po₂< 2.12 × 10⁴ Pa), Pt (+) (−) Pt, Cu₂O + Yb₂O₃ + Cu₂Yb₂O₅//CSZ//Air (Po₂ < 2.12 × 10⁴ Pa), Pt (+) in the temperature range of 1000 to 1325K. Combining the measured emf of the above cells with the chemical potential of oxygen at the reference electrode, using the Nernst relationship, gives for the reactions, 2Cu₂O(s) + 2Ho₂O₃(s) + O₂(g) → 2Cu₂Ho₂O₅(s) (1) 2Cu₂O(s) + 2Er₂O₃(s) + O₂(g) → 2Cu₂Er₂O₅(s) (2) and 2Cu₂O(s) + 2Yb₂O₃(s) + O₂(g) → 2Cu₂Yb₂O₅(s) (3) δΜo₂ = −219,741.3 + 145.671 T (±100) Jmol⁻¹ (4) δΜo₂ = −222,959.8 + 147.98 T(±100) Jmol⁻¹ (5) and δΜo₂ = −231,225.2 + 151.847 T(±100) Jmol⁻¹ (6) respectively. Combining the chemical potential of oxygen for the coexistence of Cu₂O + R₂O₃ + Cu₂R₂O₅(R− Ho,Er,Yb) obtained in this study with the oxygen potential for Cu₂O + CuO equilibrium gives for the reactions, 2 CuO(s) + Ho₂O₃(s) → Cu₂Ho₂O₅(s) (7) 2 CuO(s) + Er₂O₃(s) → Cu₂Er₂O₅(s) (8) and 2 CuO(s) + Yb₂O₃(s) → Cu₂Yb₂O₅(s) (9) δG‡ < 22,870.3 − 23.160 T (±100) Jmol⁻¹ (10) δG‡ < 21,261.1 − 22.002 T (±100) Jmol⁻¹ (11) and δG‡ < 17,128.4 - 20.072 T (±100) Jmol^-1 (12) It can be clearly seen that the formation of Cu₂R₂O₅R < Ho,Er,Yb) from the component oxides is endothermic. Further, Cu₂R₂O₅(R < Ho,Er,Yb) are an entropy stabilized phases. Based on the results obtained in this study, the oxygen potential diagram for Cu-R-O(R < Ho,Er,Yb) ternary system at 1273K has been composed.     

Excitation mechanisms of multiple Er3+ sites in Er-implanted GaN

Site-selective photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopies carried out at 6K on the ∼1540 nm ⁴I_13/2→⁴I_15/2 emissions of Er³⁺ in Er-implanted GaN have revealed the existence of four different Er³⁺ sites and associated PL spectra in this semiconductor. Three of these four sites are excited by below-gap, impurity- or defect-related absorption bands, with subsequent nonradiative energy transfer to the Er³⁺ 4f electrons; a fourth site is excited by direct Er³⁺ 4f shell absorption. PLE spectra obtained by selectively detecting Er³⁺ PL from each of the three sites pumped by broad below-gap absorption bands are compared with the PLE spectra of broad PL bands attributed to implantation damage-induced defects in the Er-implanted GaN. This comparison enables us to distinguish broad-band, below-gap optical excitation processes for Er³⁺ emission that are attributable to (1) absorption due to implantation damage-induced defects; (2) absorption due to defects or impurities characteristic of the as-grown GaN film; and (3) an Er-specific absorption band just below the band gap which may involve the formation of an Er-related isoelectronic trap. The two sites excited by impurity-or defect-related absorption bands are also strongly pumped by above-gap excitation, while the sites pumped by the Er-related trap and direct 4f shell absorption are not. This observation indicates that excitation of Er³⁺ luminescence in crystalline semiconductor hosts by either optical or electrical injection of electron-hole pairs is dominated by trap-mediated carrier capture and energy transfer processes. These trap-mediated processes may also control the thermal quenching of Er³⁺ emission in semiconductors.     

A General Ammonium Salt Assisted Synthesis Strategy for Cr3+-Doped Hexafluorides with Highly Efficient Near Infrared Emissions

The discovery of highly efficient broadband near infrared (NIR) emission material is urgent and crucial for constructing NIR lighting sources and emerging applications. Herein, a series of NIR emission hexafluorides A₂BMF₆:Cr³⁺ (A = Na, K, Rb, Cs; B = Li, Na, K, Cs; M = Al, Ga, Sc, In) peaking at ≈733–801 nm with a full width at half maximum (FWHM) of ≈98–115 nm are synthesized by a general ammonium salt assisted synthesis strategy. Benefiting from the pre-ammoniation of the trivalent metal sources, the Cr³⁺ can be more efficiently doped into the A₂BMF₆ and simultaneously prevent the generation of the competitive phase. Particularly, Na₃ScF₆:Cr³⁺ (λ_em = 774 nm, FWHM ≈ 108 nm) with optimal Cr³⁺-doping concentration of 35.96% shows a high internal quantum efficiency of 91.5% and an external quantum efficiency of ≈40.82%. A lighting emitting diode (LED) device with a NIR output power of ≈291.05 mW at 100 mA driven current and high photoelectric conversion efficiency of 20.94% is fabricated. The general synthesis strategy opens up new avenues for the exploration of Cr³⁺-doped high efficiency phosphors, and the as-obtained record NIR output power demonstrates for NIR LED lighting sources applications.     

Preparation of LaOBr:Er3+ Up-conversion Luminescent Nanobelts by Electrospinning Then Bromination

Electrospun nanobelts were prepared from lanthanum oxybromide doped with trivalent erbium ions (La₂O₃:Er³⁺), then up-conversion nanobelts were successfully synthesized from these by bromination with ammonium bromide (NH₄Br) powder as bromine source and use of a double-crucible method. The products were characterized in detail by x-ray diffractometry, scanning electron microscopy, energy dispersion spectroscopy, and fluorescence spectroscopy. The results indicated the LaOBr:Er³⁺ nanobelts were tetragonal in structure with the space group P4/nmm. The width and the thickness of LaOBr:Er³⁺ nanobelts were 3.06 ± 0.42 μm and 290 nm, respectively. On excitation with a 980-nm diode laser, LaOBr:Er³⁺ the nanobelts emitted strong green and red up-conversion emission centered at 522 nm, 541 nm, and 667 nm. The green and red emission was assigned to the energy level transitions ²H_11/2 → ⁴I_15/2, ⁴S_3/2 → ⁴I_15/2, and ⁴F_9/2 → ⁴I _l5/2 of the erbium ions (Er³⁺). A mechanism of formation LaOBr:Er³⁺ up-conversion luminescence nanobelts is proposed. This bromination technique not only results in preservation of the morphology of precursor rare earth oxides, it can also be used to fabricate other pure-phase rare earth oxybromide luminescence nanomaterials at relatively low calcination temperatures.     

Improvement of 4I11/2 → 4I13/2 Transition Rate and Thermal Stabilities in Er3+‐Doped TeO2‐B2O3 (GeO2)‐ZnO‐K2O Glasses

Spectroscopic and thermal analysis indicates that tellurite glasses doped with B₂O₃ and GeO₂ are promising candidate host materials for wide‐band erbium doped fiber amplifier (EDFA) with a high 980 nm pump efficiency. In this study, we measured the thermal stabilities and the emission cross‐sections for Er³⁺: ⁴I _13/2 → ⁴I _15/2 transition in this tellurite glass system. We also determined the Judd‐Ofelt parameters and calculated the radiative transition rates and the multiphonon relaxation rates in this glass system. The 15 mol% substitution of B₂O₃ for TeO₂ in the Er³⁺‐doped 75TeO₂‐20ZnO‐5K₂O glass raised the multiphonon relaxation rate for ⁴I_11/2 → ⁴I_13/2 transition from 4960 s^?1 to 24700 s^?1, but shortened the lifetime of the ⁴I_13/2 level by 14 % and reduced the emission cross‐section for the ⁴I_13/2 → ⁴I_15/2 transition by 11%. The 15 mol% GeO₂ substitution in the same glass system also reduced the emission cross‐section but increased the lifetime by 7%. However, the multiphonon relaxation rate for ⁴I_11/2 → ⁴I_13/2 transition was raised merely by 1000 s^?1. Therefore, a mixed substitution of B₂O₃ and GeO₂ for TeO₂ was concluded to be suitable for the 980 nm pump efficiency and the fluorescence efficiency of ⁴I_13/2 → ⁴I_15/2 transition in Er³⁺‐doped tellurite glasses.     

NIR Mechanoluminescence from Cr3+ Activated Y3Al5O12 with Intense Zero Phonon line

Mechanoluminescence (ML) materials with long-wavelength emission bands are essential for future in vivo bioimaging, non-destructive testing of solids, etc. The lack of a defined mechanism, however, prevents the application of near infrared ML materials above 650 nm in several new fields. Here, the addition of Ga³⁺ ions to Y₃Al₅O₁₂: Cr³⁺ manipulates matrix microstructure evolution, boosting near-infrared (NIR) zero-phonon line (ZPL) stress optical output of the Cr³⁺ ion at 688 nm. The key factor changing the crystal field intensity D_q/B due to the addition of Ga³⁺ ions is what causes the luminescence amplification of ZPL. The ML fabricated by composite polydimethylsiloxane and Y₃Al₄GaO₁₂: Cr³⁺ (YAGG: Cr³⁺) may penetrate chicken feet epidermal tissue and 4 mm pork tissue thanks to the strong NIR ZPL emission of YAGG: Cr³⁺ phosphor. This discovery of enhancing near-infrared ZPL intensity by solid solution provides us with a new technique for optimizing NIR ML materials, as well as a new prospect for NIR ML materials in biological applications.     

Electrochromic Switch Devices Mixing Small‐ and Large‐Sized Upconverting Nanocrystals

The hasty progress in smart, portable, flexible, and transparent integrated electronics and optoelectronics is currently one of the driving forces in nanoscience and nanotechnology. A promising approach is the combination of transparent conducting electrode materials (e.g., silver nanowires, AgNWs) and upconverting nanoparticles (UCNPs). Here, electrochromic devices based on transparent nanocomposite films of poly(methyl methacrylate) and AgNWs covered by UCNPs of different sizes and compositions are developed. By combining the electrical control of the heat dissipation in AgNW networks with size‐dependent thermal properties of UCNPs, tunable electrochromic transparent devices covering a broad range of the chromatic diagrams are fabricated. As illustrative examples, devices mixing large‐sized (>70 nm) β‐NaYF₄:Yb,Ln and small‐sized (<15 nm) NaGdF₄:Yb,Ln@NaYF₄ core@shell UCNPs (Ln = Tm, Er, Ce/Ho) are presented, permitting to monitor the temperature‐dependent emission of the particles by the intensity ratio of the Er^{3+ 2}H_11/2 and ⁴S_3/2 → ⁴I_15/2 emission lines, while externally controlling the current flow in the AgNW network. Moreover, by defining a new thermometric parameter involving the intensity ratio of transitions of large‐ and small‐sized UCNPs, a relative thermal sensitivity of 5.88% K^?1 (at 339 K) is obtained, a sixfold improvement over the values reported so far.     

Electrospinning Preparation and Drug‐Delivery Properties of an Up‐conversion Luminescent Porous NaYF4:Yb3+, Er3+@Silica Fiber Nanocomposite

Up‐conversion (UC) luminescent porous silica fibers decorated with NaYF₄:Yb³⁺, Er³⁺ nanocrystals (NCs) (denoted as NaYF₄:Yb³⁺, Er³⁺@silica fiber) are prepared by the electrospinning process using cationic surfactant P123 as a template. Monodisperse and hydrophobic oleic acid capped β‐NaYF₄: Yb³⁺, Er³⁺ NCs are prepared by thermal decomposition methodology. Then, these NCs are transferred into aqueous solution by employing cetyltrimethylammonium bromide (CTAB) as secondary surfactant. The water‐dispersible β‐NaYF₄:Yb³⁺, Er³⁺ NCs are dispersed into precursor electrospinning solution containing P123 and tetraethyl orthosilicate (TEOS), followed by preparation of precursor fibers via electrospinning. Finally, porous α‐NaYF₄:Yb³⁺, Er³⁺@silica fiber nanocomposites are obtained after annealing the precursor fibers containing β‐NaYF₄:Yb³⁺, Er³⁺ at 550 °C. The as‐prepared α‐NaYF₄:Yb³⁺, Er³⁺@silica fiber possesses porous structure and UC luminescence properties simultaneously. Furthermore, the obtained nanocomposites can be used as a drug delivery host carrier and drug storage/release properties are investigated, using ibuprofen (IBU) as a model drug. The results indicate that the IBU–loaded α‐NaYF₄:Yb³⁺, Er³⁺@silica fiber nanocomposites show UC emission of Er³⁺ under 980 nm NIR laser excitation and a controlled release property for IBU. Meanwhile, the UC emission intensity of IBU–α‐NaYF₄:Yb³⁺, Er³⁺@silica fiber system varies with the released amount of IBU.     

Concentration-dependent luminescence properties in Er3+-doped TeO2-ZnO-La2O3 glasses

Erbium-doped tellurite-based glasses(Er3+:TeO2-ZnO-La2O3) are prepared by the conventional melt-quenching technique,and concentration-dependent luminescence properties of Er3+ are investigated.A significant spectral broadening of the 1.53 μm fluorescence corresponding to 4I13/2 →4I15/2 transition is observed,and the fluorescence decaying becomes a nearly exponential way with the increasing Er3+concentration.Radiation trapping is evoked to explain the broadening of 4I13/2 → 4I15/2 emission line of Er3+ ions.The optimum doping content of Er2O3 for 1.53 μm fluorescence emission is about 1.5 mol%.     

Effect of Yb^3＋ concentration on Er^3＋ luminescence properties of sol-gelderived silica-alumina xerogels

Er~(3 )-activated silicate glasses are recognized of tech-nological interest in several areas and,in particular ,it iswell known for their successful application in opticalamplification at the C band (1530 -1565 nm) of tele-communications[1].Inside this l…     

Low energy electron excited nanoscale luminescence spectroscopy of erbium doped AIN

We have investigated the optical activity of Er³⁺ ions in AlN via depth-resolved, (5 nm to 250 nm), low energy electron-excited nanoscale (LEEN) luminescence spectroscopy and compared it with the luminescence of an Er-free AlN film. For the Er-free film, there was no emission in the IR from the AlN at any depth, and at higher energies we measured only a broad, weak feature between 1.7–3.25 eV along with an O defect related feature at 3.8 eV, which is significantly enhanced toward the surface. We found strong emission in the AlN:Er films from the first excited → ground state transition of Er³⁺ at 0.80 eV along with many other excited state transitions, although the features are broad compared to those of GaN:Er. The AlN:Er luminescence saturates near a concentration of 10²¹ cm⁻³, at which point we also observe enhanced O defect related luminescence uniformly distributed throughout the film. This finding suggests a role for O in activating the Er at low Er concentrations, while inhibiting the Er activity at high O concentrations.