Emission Of Er3 Research Articles

Growth and spectroscopy characteristics of Er, Ce:BGSO crystal: A promising material for eye-safe laser applications

Er, Ce co-doped BGSO single crystals were successfully grown by the Bridgman method. The growth parameters, including temperature gradient and growth rate, were optimized to achieve high-quality crystals. The crystal structure and morphology were characterized using X-ray diffraction and scanning electron microscopy. The optical absorption properties of Er, Ce co-doped BGSO single crystals were studied using UV–Vis absorption spectroscopy. The absorption spectrum revealed the absorption edge and the presence of absorption bands related to the presence of Ce dopant, providing valuable insights into the energy transfer processes occurring within the crystal lattice. Furthermore, the luminescence mechanism of BGSO crystals was analyzed using the Judd-Ofelt (J-O) theory, with detailed investigation into the role of ligands in spectral parameters. The photoluminescence spectra and emission decay time of Er, Ce co-doped BGSO single crystals were characterized. A comparative analysis with Er, Ce:BGSO crystals was conducted to investigate the sensitization mechanism of Ce ions on Er emission at 1.5 μm, demonstrating their potential for use as eye-safe laser materials in various applications.

Alpha sensing, NIR to green light emission in Er3+ doped PbWO4 nanoparticles with modification of calcination atmosphere

In this study, various concentrations (0.5, 1, and 1.5 at%) of Er3+ PbWO4 nanoparticles (PWO: Er NPs) were prepared using a co-precipitation procedure, and the effect of the calcination atmosphere (air and argon) on the luminescence properties and scintillation responses were investigated. Different characterization analyses were carried out to study the structural and optical characteristics of prepared samples. We found evidence of the transformation of the PWO Scheelite structure into a non-centered group, which effectively influences the symmetry properties of the structure and subsequently its luminescence and sensing properties. Both Ar atmosphere and Er concentration contribute to the distortion of the scheelite structure and the symmetry breaking. However, with increasing dopant concentrations, the lattice becomes more homogeneously distorted, causing the structure to re-symmetrize and, as a result, the intensity of luminescence increases, particularly magnetic dipolar (MD) transitions that correspond to NIR emission. The ideal conditions are given when the impurity percentage reaches 1.5 at%, in the Ar atmosphere. Our PWO: Er (1.5 at%-Ar) sample had a maximum count rate of 1388 and 2082 and detection efficiency of 0.216 and 0.170 cps/Bq under 241Am sources with 0.22 and 0.26 μc activities, respectively. By exceeding the efficiency of the commercial ZnS(Ag), it showed promising potential for practical applications in future optoelectronic domains.

IR Hidden Patterns for Security Labels.

Authentication of a product's originality by anticounterfeiting labels represents a crucial point toward protection against forgery. Fast and scalable fabrication methods of original labels with a high degree of protection are in high demand for the protection of valuable goods. Here, we propose a simple strategy for fabrication of hidden security tags with IR luminescent readout by the direct femtosecond laser patterning of silicon-erbium-silicon sandwiched thin films. The choice of laser processing parameters makes possible the creation of random or quasi-regular self-organized surface nanotextures. The controlled laser-driven oxidation accompanying this process provides simultaneous regulation of the film's optical properties and spontaneous emission yield of the embedded Er atoms. The regimes are detected when optically similar patterned areas demonstrate different Er emission intensities, allowing us to create hidden security tags with facile readout at the C-band telecommunication wavelengths. The obtained results take another step toward the application of IR-luminescent erbium-based anticounterfeiting labels for covert and/or forensic security levels.

Maximizing Nanoscale Downshifting Energy Transfer in a Metallosupramolecular Cr(III)-Er(III) Assembly.

Pseudo-octahedral CrIIIN6 chromophores hold a unique appeal for low-energy sensitization of NIR lanthanide luminescence due to their exceptionally long-lived spin-flip excited states. This allure persists despite the obstacles and complexities involved in integrating both elements into a metallosupramolecular assembly. In this work, we have designed a structurally optimized heteroleptic CrIII building block capable of binding rare earths. Following a complex-as-ligand synthetic strategy, two heterometallic supramolecular assemblies, in which three peripherical CrIII sensitizers coordinated through a molecular wire to a central ErIII or YIII, have been prepared. Upon excitation of the CrIII spin-flip states, the downshifted Er(4I13/2 → 4I15/2) emission at 1550 nm was induced through intramolecular energy transfer. Time-resolved experiments at room temperature reveal a CrIII → ErIII energy transfer of 62-73% efficiencies with rate constants of about 8.5 × 105 s-1 despite the long donor-acceptor distance (circa 14 Å). This efficient directional intermetallic energy transfer can be rationalized using the Dexter formalism, which is promoted by a rigid linear electron-rich alkyne bridge that acts as a molecular wire connecting the CrIII and ErIII ions.

Quantum-plasmonic engineering to improve the 1.53 µm radiative emission in Er3+-doped tellurite glasses under controlled temperature

The plasmonic applications at low temperatures of metallic nanoparticles in glasses doped with rare-earth ions are not yet covered in-depth analysis in the literature. This paper insights into the coupling between gold nanoparticles and Er3+ embedded in tellurite glasses via luminescence enhancement of the emission centred at 1.53 µm under controlled temperature. This enhancement is obtained for the sample with 24 h of heat treatment (TErAu24) concerning the Er3+ single doped (TEr) at room temperature under 980 nm excitation. The enhancement remains under cooling conditions, consequence of the strong coupling between the plasmon and the Er3+, attributed to an increment of the localized plasmon mode volume at low temperatures. Further, the band area increment of the TErAu24 sample comparing the spectra at 98 and 348 K is 414 %, whereas for the TEr is about 348 %. These findings provide advanced understanding of the plasmonics on quantum emitters engineering.

Enhancing 2.7 µm emission of Er3+ in bismuth glass by introducing ZnO

In recent years, 2.7 μm lasers have attracted the attention of many researchers due to their wide application in military, medical, aerospace and other fields. This study investigates the gain effect of ZnO on Er3+-doped bismuthate glasses by partially replacing GeO2 in the glass with ZnO. It is found that under 980 nm pump excitation, with the increase of ZnO, the emission of Er3+ at 1.5 μm and 2.7 μm was enhanced. This result is consistent with the changing trend of J-O parameter Ω2. All these results confirmed that the introduction of ZnO into bismuthate glasses is a reasonable and effective method to enhance the mid-infrared 2.7 μm emission in Er3+-doped bismuthate glasses. Therefore, the current research indicates that an appropriate amount of ZnO in Er3+-doped bismuthate glasses is a suitable materials for 2.7 um fiber lasers.

Evolutionary behavior of thermal and optical properties of fluoride fiberglass with Er3+ doping

AbstractEr3+‐doped fluoride glass and fiber have been widely used in multiple fields such as mid‐infrared laser, visible laser, and amplifier. However, there is no unified conclusion on the thermal and optical properties with respect to varying concentrations of Er3+ doping. Furthermore, this is a paucity of systematic guidance on the preparation of Er3+‐doped fluoride glass and fiber. In this study, fluorozirconate fiberglass with Er3+ doping is systematically examined. Additionally, a preliminary explanation of the evolutionary behavior of glass devitrification, thermal properties, and fluorescence properties is provided. Energy transition models were built for 1.5 and 2.7 µm emissions in Er3+‐doped fluorozirconate at room temperature. Moreover, a suitable doping concentration is proposed based on the evolutionary behavior of thermal and optical properties. In this study, guidance on appropriate Er3+ doping concentration levels in fluorozirconate glass is provided and potential applications are explored.

Sm3+ as effective deactivator for enhanced ∼3 μm laser emission in Er,Sm:SrLaAlO4 crystal

A promising mid-infrared (MIR) laser crystal with Er, Sm co-doped SrLaAlO4 (Er,Sm:SLA) crystal was successfully grown using the Czochralski (CZ) method. It was the first time that co-doped Sm3+ ion as deactivator for Er3+ activated ∼ 3.0 μm laser. The crystal structure, absorption spectra, emission spectra, and energy level lifetime were discussed in detail. The band structure and density of states were calculated by the density functional theory. The spectral parameters were calculated using Judd-Ofelt (J-O) theory and the deactivate effect of Sm3+ was systematically studied. The introduction of Sm3+ ions enhance the 2.7 µm mid infrared emission intensity by three times, and decrease the lifetime of 4I13/2 energy level of Er3+ ion from 4.35 ms to 0.98 ms. The lifetime ratio of upper and lower levels for 2.7 µm emission was calculated to be 0.63, which is 2.6 times of Er:SLA crystal and comparable to some commercial crystals. All the results indicate that the Sm3+ ion is an effective deactivator for ∼3 μm laser emission. The long upper level lifetime, as well as the large lifetime ratio, the broadening spectra characteristics and the appropriate emission cross-section show the Er,Sm:SLA crystal a good gain material for ultrafast and tunable lasers at ∼3.0 μm.

Exploring the optical properties of the 1.53 μm emission in Er3+-doped glass, anti-glass and ceramic in TeO2 - Ta2O5 – Bi2O3 system

A series of 80TeO2 - 10Ta2O5 – 10Bi2O3 glasses, anti-glasses and ceramics doped with different concentrations of Er₂O₃, ranging from 0.25 % to 2 % mol, were synthesized to explore their structural transformation and optical properties. The maximum solubility of Er₂O₃ was identified at 1.25 % mol, beyond which the glass transitioned from an amorphous to a crystalline structure. The anti-glasses and ceramics obtained from the heat treatment of the parent glasses were also studied to gain insights into their optical properties. This study reveals a direct relationship between Er3+ ions concentration and full width at half maximum (FWHM) of photoluminescence spectra. The increase in Er3+ ions concentration correlates with a rise in FWHM, indicative of spectral broadening. Anti-glass exhibits a higher emission intensity, followed by ceramic and then glass, reflecting their distinct structural properties. Anti-glass doped with 1 % mol Er2O3 shows an FWHM over 130 nm under 578 mW pumping. The lifetime of the excited state 4I13/2 increases with the Er2O3 content in the anti-glass and the ceramic, with a notable decrease at 1 % mol Er2O3 ions for both materials, while in glass, the decrease is observed at 0.5 %. Emission cross-sections decrease with increasing Er3+ ions concentration and power, influenced by factors like thermal effects and saturation. The Judd-Ofelt theory highlights structural differences, with glasses having a more disordered structure and with an increase in the Ω₆ parameter across all materials, implying enhanced electric dipole line strength and spontaneous emission probability with higher Er₂O₃ content. Overall, this comprehensive study provides valuable insights into the optical behavior of Er3+ ions in these materials, essential for applications in laser design and optical amplifiers.

Influence of Yb3+ percentage on emission of Er3+ doped into GdVO4 matrix

In this study, we used the non-hydrolytic sol–gel methodology to synthesize gadolinium vanadate particles doped with different Er3+ and Yb3+ molar ratios. Er3+ and Yb3+ chlorides and vanadium alkoxide were used as precursors during the sol–gel synthesis. The resulting powders were treated at 800 °C and characterized by x-ray diffraction and photoluminescence. The x-ray diffractogram displayed peaks attributed to the gadolinium vanadate matrix. Photoluminescence helped to evaluate the Fluorescence Intensity Ratio (FIR), which is important for understanding the nanothermometer property. The FIR of the GdVO4:Er3+/Yb3+ samples containing different Er3+ and Yb3+ molar ratios increased as a function of the laser power, which indicated that the local temperature increased. The excitation spectra obtained at fixed wavelengths of 525 and 555 nm displayed bands at 322, 379, and 489 nm, ascribed to the charge transfer band and Er3+ levels. Upon excitation at 321 nm, the emission spectra in the visible region presented intense bands at 525 and 555 nm, due to Er3+ emission, and excitation at 321 nm led to emission in the infrared region, 980 and 1550 nm. In conclusion, the synthesized system can be employed as a temperature sensor.

Enhanced up-conversion luminescence and temperature sensing performance of NaBiF4: Er3+, Yb3+, Al3+

Rare earth doped fluoride-based up-conversion luminescent materials have been widely studied in non-contact temperature sensing technology. However, the luminous intensity of the fluoride at high temperature still needs to be improved. Here, enhanced up-conversion luminescence and temperature sensing performance of NaBiF4: Er3+, Yb3+ is realized by Al3+ substitution. The samples exhibit the characteristic green (521 nm and 540 nm) and red (654 nm) emissions of Er3+ ion under 980 nm excitation. When the concentration of Al3+ is 5%, the green emission is enhanced by about 10 times, and the red light is enhanced by about 7 times. Obvious lattice shrinkage caused by the introduction of Al3+ is responsible for the enhancement. In addition, the optimal sample is highly thermally stable from 303 K to 443 K. The maximum relative sensitivity at 303 K increases from 0.791% K−1 to 1.106% K−1. The results indicate that NaBiF4: Er3+, Yb3+, Al3+ be a potential thermosensitive material.

Enhanced upconversion emission in Nd, Yb, Er and Ho tetra-doped Y2O3 phosphor

Yb3+, Nd3+, Er3+ and Ho3+ tetra ions doped Y2O3 upconversion phosphors have been prepared by the combustion route. Crystalline phase purity and cubic phase of prepared samples have been confirmed from powder X-ray diffraction study. Absorbance of samples over spectral range 200–1100 nm has been measured by diffuse reflectance spectroscopy. All samples exhibit large band gaps. Scanning electron micrograph analysis reveals spherical morphology of particles and sizes around 200 nm. Upconversion emission has been studied under a 980 nm diode laser excitation with 166 mW laser power. The Ho3+, Nd3+ and Yb3+ co-doped Y2O3 phosphor show very high emission intensity of a green band centred at around 550 nm and another moderate intensity red band centred on 667 nm, while reverse is the case for Er3+, Nd3+ and Yb3+ co-doped Y2O3 phosphor. Er3+, Ho3+, Nd3+ and Yb3+ co-doped Y2O3 phosphor show enhanced high emission intensity in both green and red bands. These two bands are not visible in Nd3+ and Yb3+ co-doped Y2O3 phosphor but show weak upconversion emission at 549, 568 and 799 nm. Owing to the high emission intensity of green band, Ho3+, Nd3+ and Yb3+ co-doped Y2O3 phosphor may find potential applications in medical and security, while Er3+, Ho3+, Nd3+ and Yb3+ co-doped phosphor showing enhanced upconversion in green and red bands may find applications in white light generation.

Net gain in C+L band from LED pumped broadband emission in Er3+-doped oxyhalide tellurite glass

Expanding gain bandwidth into the L-band for erbium-doped fiber amplifiers (EDFAs) is a crucial strategy to overcome limitations in prevalent C-band focused commercial silica-based EDFAs, significantly boosting optical network transmission capacity. Herein, we synthesized Er3+-doped broadband near-infrared emission tellurite glasses utilizing the melt quenching process, systematically exploring the impact of ZnCl2 on the glass structure and optical properties. The 82TeO2–3Nb2O5–15ZnCl2–3Er2O3 (TNZ15) glass emerged as a standout candidate for broadband amplifiers around wavelength at 1.55 μm. With escalating ZnCl2 concentration, a discernible red shift in the emission peak wave lines was observed, accompanied by an expansion of the full width at half maximum (FWHM) from 98 nm to 106 nm. Noteworthy characteristics of all samples included exceptional thermal stability and elevated near-infrared (NIR) transmittance. Application of the Judd-Ofelt (J-O) theory facilitated the calculation of J-O parameter intensity, providing deeper insights into the optical behavior of the materials. Finally, the evaluation of TNZ15 planar optical waveguides, employing the vertical top pumping mode of two 980 nm LEDs, encompassed both the C-band (1530–1565 nm) and the L-band (1565–1625 nm). The results underscore the potential of TNZ15 glass as a promising gain material for broadband optical amplifiers and lasers, offering valuable insights into the development of next-generation optical amplification technologies.

In-band luminescence thermometry in the third biological window and multicolor emission of Er-doped fluoride and oxide nanoparticles

In this study we present a morphological and spectroscopical characterization of three different erbium doped nanocrystal samples, namely two oxides (Y2O3:3%Er, Sc2O3:3%Er) and one fluoride (YF3:5%Er). The spectroscopic study offers a comprehensive comparison of their multicolor emissions, ranging from the visible to the mid-infrared region. Emissions from the first five excited states are presented and the emission cross sections of the 4I11/2 → 4I15/2, 4I11/2 → 4I13/2, and 4I13/2 → 4I15/2 transitions have been calculated and compared with literature results for the oxide compounds providing a confirmation for the 1.5 μm emission of Er:Y2O3, a correction over published values for the 2.7 μm emission of Er:Y2O3, and also new results for the Er:Sc2O3 emission cross section values of all the infrared bands. Moreover, this study explores the application of the 4I13/2 emission for in-band luminescence thermometry within the third biological window. An optimized segmentation of the 1.5 μm emission permits to achieve high relative and absolute sensitivities using just one dopant ion.

Enhanced Efficiency, Broadened Excitation, and Tailored Er3+ Luminescence Triggered by Te4+ Codoping in Cs2NaYbCl6 Crystals for Multifunctional Applications.

The quest for efficient and tunable luminescent materials has been at the forefront of research in the fields of chemistry and materials science. This work delves into the investigation of the luminescence properties of Er3+ ions triggered by 1% Te4+ in the environmentally benign perovskite Cs2NaYbCl6 (CNYC) crystals, aiming to enhance their efficiency and tune the luminescence color. The ratio of the green (2H11/2, 4S3/2-4I15/2) to red (4F9/2-4I15/2) emissions of Er3+ can be freely tunable by varying the concentration of Er3+ and producing the defects induced by codoping Te4+. The calculations reveal that the multiexcitonic excitations of Er3+ stem from f-f (4I15/2-4G11/2, 2H9/2) rather than d-f transitions. The broadened excitation, tuning of color, and enhancement of efficiency achieved in the luminescence perovskite crystals Cs2NaYbCl6:Te4+, Er3+ (CNYC:Te4+,Er3+) presents promising opportunities for the development of advanced optoelectronic devices with superior performance. Moreover, our investigation demonstrates the tunable luminescence response of CNYC:Er3+ to temperature variations, offering potential applications in temperature sensing.

Enhancement mechanism of red up-conversion emission in single NaYbF<sub>4</sub>:2%Er<sup>3+</sup>@NaYbF<sub>4 </sub>micron core-shell structure

The construction of core-shell structure can effectively reduce the quenching effect on the surface of material and regulate ion-ion interaction, which has become one of the effective ways to enhance and regulate the spectral characteristics of rare-earth upconversion luminescent materials. In this paper, a variety of NaYbF<sub>4</sub>: 2%Er<sup>3+</sup> micron core-shell structures are constructed with the help of epitaxial growth technology, effectively improving the red up-conversion emission of Er<sup>3+</sup> ions. The prepared microcrystals with core-shell structures are of hexagonal phase microdisks, and their sizes are relatively uniform. In order to better obtain the material spectral data, a confocal microscopic spectroscopy is used to study spectral properties. Under 980 nm near-infrared laser excitation, the red emission intensity of single NaYbF<sub>4</sub>:2%Er<sup>3+</sup>@NaYbF<sub>4</sub>@NaYF<sub>4</sub> core-shell-shell microdisk is 4.6 times higher than that of NaYbF<sub>4</sub>:2%Er<sup>3+</sup> micron disk, and the red-to-green ratio increases from 6.3 to 8.1. Meanwhile, Ho<sup>3+</sup> ions are introduced into the NaYbF<sub>4</sub>:2%Er<sup>3+</sup>@NaYbF<sub>4</sub>: 2%Ho<sup>3+</sup> @NaYF<sub>4</sub> core-shell-shell microdisk, and the red emission intensity is nearly 6.7 times higher than that of single NaYbF<sub>4</sub>: 2%Er<sup>3+</sup> microdisk, and the red-to-green ratio increases from 6.3 to 9.4 through the interaction between ions. The microcrystal spectral characteristics and luminescence kinetics of different core-shell structures are studied, showing that the red emission enhancement of Er<sup>3+</sup> ions is mainly derived from the construction of different core-shell structures, which can effectively enhance the cross-relaxation between Er<sup>3+</sup> ions, the energy back transfer between Yb<sup>3+</sup> and Er<sup>3+</sup> ions, and the energy transfer from Ho<sup>3+</sup> ions to Er<sup>3+</sup> ions. The micron core-shell structures with efficient red emission in this study has great application prospects in the fields of luminescence, anti-counterfeiting and optoelectronic devices.

Novel insights into the electronic and optical properties of the 1.53-μm emission in Er3+-doped oxide- and oxyfluoride- tellurite glasses for optical communications

There is a continuous search for novel technologies to extend the NIR emission and expand the operation range of current Er-doped silica-based glasses. In this sense, it is important to understand the different interactions between the Er3+ ions and the glass structure and how it influences the 4I13/2→4I15/2 emission. The intrinsic features of tellurite glasses make them to be promising candidates. The effect of the glass composition was evaluated by comparing oxide and oxyfluoride-based tellurite glasses. These results show that the distribution of electrons in Stark levels have population dynamics obeying the Fermi-Dirac distribution against the traditional Maxwell-Boltzmann function usually considered. In addition, this work explores how the Er3+ ion emissions at 1.53 µm can be engineered. We demonstrate how the luminescence from the 4I13/2→4I15/2 transition of Er3+ ions is affected by the doping concentration, showing an increase in the emission output of the oxide and oxyfluoride glasses, with up to 5.0 mol% of Er2O3, and a FWHM over 100 nm under 104 mW pumping. The variations in the emission were also assessed as related to pumping power and temperature. Under cooling, the emission intensity increased over the infrared and the emission underwent a redshift, whereas the increasing temperature led to a blueshift with a variation of FWHM ranging from 90 to 140 nm. The analysis presented in this work elucidates the different aspects involved in the emission of Er3+ ions while highlighting the versatility of these tellurite glasses as a promising glass matrix for optical communications with operations in Er3+ emission window.

Dynamic manipulation of multimodal emission in Er3+-activated non-core–shell structure for optical thermometry and information security

Dynamic manipulation of multimodal emission in Er3+-activated non-core–shell structure for optical thermometry and information security

Revisiting the luminescence properties of Er3+, Tm3+ and Ho3+ doped Bi4Ge3O12 rod-type crystal fibers for the laser application

BGO single crystals doped with Er3+, Tm3+ and Ho3+ rare-earth ions were prepared in the form of rod-type crystal fibers via the micro-pulling down technique to perform an extensive investigation of their visible, near- and mid-infrared luminescence properties and to really decide on their interest as solid-state laser media in the various spectral domains. Revisiting and completing the absorption spectra already available in the literature led to the derivation of more reliable “effective” radiative lifetimes and branching ratios. Registration of the fluorescence decays of the most important emitting levels versus dopant concentrations led for the first time to an unambiguous determination of “intrinsic” emission lifetimes – corresponding to negligible contributions from inter-ionic energy-transfers - and non-radiative multiphonon relaxation rates. Such data also allowed for the determination of the dominant phonon energy which comes into play in the electron-phonon coupling responsible for these multiphonon relaxation processes and for its lattice vibration origin, i.e. a high phonon energy of the order of 820 cm−1 corresponding to the coupling between bending vibrations of (GeO4)4- tetrahedra and vibrations corresponding to motions of these (GeO4)4- tetrahedra against the Bi3+ ions for which the rare-earth dopant ions substitute. Using the above data and different methods for the calibration of the registered emission spectra in cross section unit and for the derivation of gain cross section curves finally show that mid-infrared emissions of Er:BGO, Tm:BGO and Ho:BGO around 1.55 μm, 1.9 μm and 2 μm, respectively, occur with comparable gain cross sections as in the most important reference mid-infrared laser materials, although over slightly shifted thus complementary spectral domains. It is shown that potentialities also exist with Tm:BGO in the blue, deep-red and near-infrared spectral domains around 470 nm, 800 nm and 1.45 μm, by pumping the crystals with conventional pump sources and using some suitable co-dopants to avoid detrimental self-terminating processes.

Cooperative-luminescence-assisted single-band upconverted red emission in Er3+ and Yb3+ co-doped MgAlON transparent ceramic

Although single-band emission upconversion fluorescence, which is particularly important in sensors, biomedical and imaging applications, has been extensively investigated in nanoparticles using energy transfer engineering, it is still difficult to be achieved in transparent ceramics. Herein, the MgAlON: Er3+/Yb3+ transparent ceramics with functionalized grain boundaries were successfully fabricated. Lanthanide ions were investigated to highly enrich at the MgAlON grain boundaries, resulting in novel fluorescent properties. Upon 980 nm laser excitation, the sample emitted temperature and excitation power-independent single-band red upconverted fluorescence with a red-to-green fluorescence intensity ratio of ∼25. The new mechanism of Yb3+-Yb3+ cooperative fluorescence-assisted energy transfer, which is responsible for the single-band feature, was elucidated. Moreover, the upconverted fluorescence chromaticity can be modified by the excitation wavelength, relying on the existence of the cooperative fluorescence level and its related energy transfer mechanism. This work reveals the potential of grain boundary functionalization of transparent ceramics in energy transfer engineering.