Transparent Er3 Research Articles

Er3+/Tm3+ codoped CaF2 based oxyfluoroborosilicate glass-ceramics for fiber laser applications

Transparent Er3+/Tm3+ codoped CaF2 based oxyfluoroborosilicate glass-ceramics (BSEr1TmxGCs) with variable Tm3+ concentration were prepared through melt quench process followed by reheat treatment at 450 °C/1h. They were characterized through differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) Raman spectroscopy, near infrared (NIR) emission and luminescence decay. The formation of CaF2 nanocrystallites against oxyfluoroborosilicate glassy phase was confirmed by scanning electron microscopic (SEM) and hi-resolution transmission electron microscopic (HRTEM) studies. The NIR emission properties were investigated at 460 nm diode laser pumping. The applicability of BSEr1TmxGCs were examined by evaluating effective bandwidth (Δλeff), stimulated emission cross-section (σe), gain bandwidth (σe × Δλeff), figure of merit (σe × τR) and quantum efficiency (ηQE). The energy transfer efficiency (ηET), rate of energy transfer (WET) between Er3+ and Tm3+ and the rate of non-radiative transitions (WNR) were also calculated. The comparative NIR emission performance suggests that the BSEr1Tm1GC has proficiency for 1530 nm broadband fiber lasers and optical amplifiers in short wavelength and conventional wavelength (S + C) band communication window.

Growth, Spectroscopic Characterization and Continuous-Wave Laser Operation of Er,Yb:GdMgB5O10Crystal

A transparent Er3+,Yb3+:GdMgB5O10 single crystal with dimensions up to 24 × 15 × 12 mm was grown successfully by the high-temperature solution growth on dipped seeds technique from K2Mo3O10-based solvent. The grown crystal was characterized using PXRD, DSC and ATR techniques. Differential scanning calorimetry measurements and SEM analysis of the heat-treated solids revealed Er,Yb:GdMgB5O10 to be an incongruent melting compound with an onset point of 1087 °C. The absorption edge of the Er,Yb:GMBO sample is located in the region of 245 nm, which approximates a value of 4.8 eV. Absorption and emission spectra, and luminescence kinetics, were studied. The energy transfer efficiency from ytterbium to erbium ions was determined. The laser operation in continuous-wave mode was realized and output characteristics were measured. The maximal output power of 0.15 W with a slope efficiency of 11% was obtained at 1568 nm.

Fabrication and Luminescent Properties of Highly Transparent Er:Y2O3 Ceramics by Hot Pressing Sintering.

Highly transparent Er:Y2O3 ceramics (1-9 at.% Er) were fabricated by hot pressing sintering with ZrO2 as the sintering additive. The microstructures, transmittance, luminescent properties, thermal conductivity, and mechanical properties of the Er:Y2O3 ceramic samples were investigated in detail. The samples all exhibited dense and fine grain microstructures; the average grain sizes were about 0.8 μm. The transmittance levels of the samples with various Er concentrations (2 mm thick) at the wavelengths of 600 and 2700 nm were ~74 and ~83%, respectively. As the Er doping concentration increased from 1 to 9 at.%, the up-conversion luminescence of the samples gradually changed from green to red, with the intensity ratio of red/green light increasing from 0.28 to 2.01. Meanwhile, the down-conversion luminescence properties of the specimens were also studied. When the samples were under 980 nm excitation, the emission bands were detected at 1552, 1573, 1639, and 1661 nm. The thermal conductivity of the samples was found to decrease from 8.72 to 5.81 W/(m·K) with an increase of the Er concentration from 1 to 9 at.%. Moreover, the microhardness and fracture toughness of the samples with 1 at.% Er concentration were ~8.51 GPa and ~1.03 MPa·m1/2, respectively.

Improved sensitivity of temperature sensor based on three-photons pumped upconversion in highly transparent Er3+ doped lead lanthanum zirconate titanate ceramics

Efficient two-photons and three-photons pumped upconversion emission were investigated in highly transparent Er3+ ions doped lead lanthanum zirconate titanate ceramics excited by using near infrared lasers centered at 980 nm, 1064 nm, and 1550 nm. Temperature dependent spectral changes of the multi-photons upconversion emission were explored, and highly sensitive temperature sensors were obtained based on the energy difference between 2H11/2 and 4S3/2. Using this temperature sensor, the temperature changes of the Er3+ ions doped lead lanthanum zirconate titanate ceramics was tested by irradiating the sample with a high-energy femtosecond laser at 1550 nm. This work is useful for developing a highly sensitive non-contact temperature measurement sensors, which provides the necessary theoretical basis for its practical application.

Er3+ doped sesquioxide Y2O3 optical ceramics: synthesis and spectral-luminescent properties

In this conribution we describe the technological process of transparent Er3+:Y2O3 ceramic synthesis, a prospective medium for future laser applications. Hot isostatic pressing (HIP) was used to improve the optical quality of the final product. As the results of our efforts the material with an optical transmission of 0.78-0.80 was obtained, that is close to the theoretical maximum value of 0.83. The main spectral and luminescent properties of the created Er3+:Y2O3 optical ceramics in the spectral range of 1.4-1.65 microns was determined and is reported in this work.

(INVITED)Transparent Er3+ doped Ag2O containing tellurite glass-ceramics

Transparent Er3+ doped Ag2O containing tellurite glass-ceramics were fabricated by melting process followed by a heat treatment at 20 °C above the glass transition temperature of the glass for 2 to 17 h. The effects of the crystallization on the optical and luminescence properties of the glasses are presented and discussed. The precipitation of Bi4TeO8 crystal was confirmed in all the glasses, independently of their composition. From the spectroscopic properties, the heat treatment was found to have no impact on the site of the Er3+ ions indicating that the Er3+ ions remain in the amorphous part of the glass-ceramic. Although Ag nanoparticles could be evidenced using transmission electron microscopy and nonlinear optical imaging, no surface plasmon resonance band of Ag nanoparticles appeared in the absorption spectrum of the heat treated glasses. No enhancement of the NIR emission centered at 1.5 μm was observed probably due to the low concentration of Ag nanoparticles precipitating in the glasses. However, an increase in the intensity of the upconversion and mid-infrared emissions was observed from the glass-ceramics prepared with the low amount of Ag2O (<1 mol%). As evidenced using Raman spectroscopy, the addition of Ag2O was found to depolymerize the tellurite network. The precipitation of the Bi4TeO8 crystal in the most polymerized glasses is suspected to reduce the Er–Er distances whereas it has no significant impact on the Er–Er distances in glasses with a depolymerized network.

Assessment of optical and fluorescence aspects of Er3+-doped multicomponent B2O3 glasses as active media for 1.532 μm near-infrared optical amplifiers

Current work principally provides an idea on controlling the Er3+: NIR (near-infrared) emission characteristics by changing a glass constituent and finding a suitable glass host favorable to design a novel C-optical band (1.53–1.565 μm) amplifier. By melting and rapid quench route, six transparent Er3+ (1 mol%)-doped B2O3-rich glasses having different single and mixed alkali ions were fabricated, and optical and fluorescence (visible and NIR) traits including Er3+ ion upper-levels 4S3/2 and 4I13/2 decay dynamics were inspected for such samples. At 1.4–1.65 μm wavelength range, an intense and wide NIR luminescence band centered at 1.532 μm (Er3+: 4I13/2 → 4I15/2 transition) has been obtained by a 980 nm laser diode pumping (4I15/2 → 4I11/2). NIR fluorescence Δλeff (effective bandwidth) varied depending on added single or mixed alkali ions, and a maximum Δλeff ∼74.66 nm was acquired for Er3+: Li ions constituting glass. For the 4I13/2 → 4I15/2 transition, σemi (stimulated emission cross-section) was evaluated using both Füchtbauer–Ladenburg and McCumber's theories. In all glasses, comparably, higher gain bandwidth (= 5.384 × 10−26 cm3) and peak σemiM (= 1.692 × 10−20 cm2) values have been attained for 4I13/2 → 4I15/2 transition in Li ions containing sample, and also this glass possesses the largest σabs (absorption cross-section) (= 1.459 × 10−20 cm2) for 4I15/2 → 4I13/2 transition. Further, at distinctive P (population inversion) values, gain spectra were computed, and all samples show C-optical band amplification beginning from P = 50%. All analyzed NIR fluorescence results indicate that Li ions having glass could be a potential gain medium for fiber amplifiers.

Fabrication and comprehensive structural and spectroscopic properties of Er:Y2O3 transparent ceramics

Transparent Er:Y2O3 ceramics with sub-micron grain size (<1 μm) were fabricated by using one-step vacuum sintering followed by hot isostatic pressing (HIPing) technique. The transmission of the undoped Y2O3 reaches 83%. The structural characteristics including the phonon energy were investigated through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) analysis and scanning electron microscopy (SEM) measurement. The overall spectroscopic properties of transmission, fluorescence emission up to 3000 nm, lifetime, up-conversion luminescence, and refractive index were systematically studied for both 0.25 at% and 7.0 at% Er:Y2O3 ceramics with different thicknesses. The comparison of the spectra of the fluorescence emission and up-conversion luminescence under both 976 and 808 nm laser excitation was performed. The multiple high-energy-state transitional processes after the excited state absorption (ESA) processes involved in the up-conversion are discriminated between the multi-phonon non-radiative transitions and the radiative transitions according to the measured maximum phonon vibrational energy. The calculation was performed based on the Judd–Ofelt theory.

Er3+‐Yb3+ ions doped fluoro‐aluminosilicate glass‐ceramics as a temperature‐sensing material

AbstractThe transparent Er3+‐Yb3+‐doped fluoro‐aluminosilicate glass‐ceramic (GC) was prepared by melt‐quenching. The crystal phase, morphology, and up‐conversion (UC) luminescence of as‐produced GC were characterized by X‐ray diffraction, scanning electron microscopy, and fluorescence spectrophotometry, respectively. The results show that BaYF5 nanocrystals were uniformly distributed in the glass matrix of the as‐produced GC. When the as‐produced GC was subjected to heat treatment, the crystallinity was increased, but the crystal identity remains unchanged. Such heat‐treatment doubled the intensity of the UC luminescence, and this enhancement was ascribed to the increased incorporation of both Er3+ and Yb3+ ions into the lower phonon energy environment of BaYF5 nanocrystals. Furthermore, the heat‐treated GC was stable against further crystallization, and consequently its UC luminescence was stable at the application temperature. The heat‐treated GC was found to possess an outstanding temperature‐sensing capability.

Fabrication of highly transparent Er3+, Yb3+:Y2O3 ceramics with La2O3/ZrO2 as sintering additives and the near-infrared and upconversion luminescence properties

Abstract Highly transparent Er3+, Yb3+:Y2O3 ceramics were fabricated by pressureless vacuum sintering method using La2O3 and ZrO2 as compound sintering additives. The microstructure, optical transmittance, upconversion and near-infrared spectral properties of the ceramics were investigated by X-ray diffraction, scanning electron microscopy, energy-dispersive spectrometry and spectroscopic analysis methods. The sintered ceramics displayed a pure cubic Y2O3 phase structure and a nearly pore-free microstructure with homogeneous grain morphology and grain-size distribution. The highest transmittance of Er3+, Yb3+:Y2O3 ceramics sintered at 1800 °C for 14 h with 9 at% of La2O3 and 3 at% of ZrO2 as compound additives was more than 82% in the range of 380–3000 nm. Under 980 nm wavelength excitation, the ceramics exhibited intense blue, green and red upconversion emission, and broad-bandwidth near-infrared emission centered at 1536 nm, which gives it the potential to act as a high-performance solid-state 1.54 μm near-infrared and upconversion laser gain media.

Phase-separation engineering in fluorozirconate glass for designing and fabricating of transparent perfluorinate glass ceramic

Perfluorinate glass ceramics with ultra-low phonon energy are very important optical and photonic materials. Unfortunately, there is no suitable method to obtain transparent perfluorinate glass ceramics due to poor thermal stability of fluoride glass. As a result, wide applications of glass ceramics in advanced infrared systems are restricted. Here, an effective method based on phase-separation engineering is used to develop transparent perfluorinate glass ceramics. In this article, a novel transparent Er3+-doped ZnZrF6-Ba6Zn7F26 perfluorinate glass ceramic was designed and fabricated by phase-separation engineering. The sample exhibits low phonon energy (564 cm−1), ultra-wide transmission range (0.33–8.2 μm, T ≥ 50 %), and strong infrared emission, which is better than that of ZBLAN glass, oxide-, and oxyfluoride-glass ceramics. These good properties of the perfluorinate glass ceramic demonstrate that phase-separation engineering not only offers an effective approach to obtain perfluorinate glass ceramics but also provides wide-ranging opportunities for advanced infrared optical and photonic materials.

Novel transparent Er3+ doped perovskite glasses fabricated by containerless solidification

Perovskite glasses with the compositions of La0.85-xErxBi0.15Al0.5Ga0.5O3 (x = 0.025, 0.05, 0.1, 0.125, 0.15) and remarkable electrical insulation performance were synthesized by containerless solidification. The x = 0.15 amorphous material had the highest Vicker's hardness (7.34 GPa). The transmittance reached as high as 86% in the infrared (IR) region. The absorption peaks in the UV–vis–NIR region of transmittance spectra could be attributed to the transitions of Er3+ ions from the ground state 4I15/2 to excited states. All transparent samples emitted intense green emissions when excited at 379 nm, corresponding to the 2H11/2 and 4S3/2 to 4I15/2 transitions of Er3+ ions. The average decay life-time decreased from 25.3 μs to 6.1 μs with increasing Er3+ ion content, revealing the interaction within Er–Er clusters.

Enhanced mid-infrared emission by energy transfer in Er3+/Yb3+ co-doped zirconium fluoride-chloride transparent glass

Transparent Er3+/Yb3+ co-doped zirconium fluoride-chloride (ZFC) glass are firstly prepared for mid-infrared emission. The stronger 2750 nm emission from Er3+: ZFC glass is owing to a stronger covalence and local asymmetry of the crystal field around the Er3+ ions. The low phonon energy (600 cm−1) of ZFC glass are calculated from FTIR spectra and confirmed by Raman spectra. The low OH− concentration (9.75 × 10−17 cm−3) and high transmittance (1300-4000 cm−1) of ZFC glass are beneficial to mid-infrared emission. Co-doping rare earth ions Yb3+ enhances the 2750 nm emission. The energy transfer process between Yb3+ and Er3+ are identified based on luminescence spectra and decay curves. The role of Yb3+ plays the sensitizer on Er3+: 4I11/2 and enhances the excited state absorption of Er3+: 4I13/2 → 4F9/2, which is good for transition Er3+: 4I11/2 → 4F13/2. Thus, Er3+/Yb3+: ZFC glass with large emission cross section (1.06 × 10−20 cm2) is a potential laser application material.

A transparent and dual-functional oxyfluoride glass ceramics with color-tunable up-conversion luminescence and high thermosensitivity

Transparent and dual-functional Er3+/Tm3+/Yb3+ tri-doped β-PbF2 glass ceramics (GCs) were synthesized successfully by the conventional melting-quenching method. Under 976 nm laser excitation, intense and typical emissions of Tm3+ and Er3+ with good signal discriminability were simultaneously observed. Just through regulating Er3+ concentration, a color-tunable emission over a large range of “purplish blue→cool white→green→reddish orange” was achieved in Er3+/Tm3+/Yb3+ tri-doped β-PbF2 GCs upon 976 nm laser excitation. Additionally, besides two pairs of conventional thermally coupled energy levels (TCELs) of Er3+ and Tm3+, temperature sensing property of the Er3+/Tm3+/Yb3+ tri-doped β-PbF2 GCs was investigated based on a novel coupled energy levels, 3F2,3 (Tm3+)/4S3/2 (Er3+). Fortunately, the relative sensitivity Sr of the novel coupled energy levels of 3F2,3 (Tm3+)/4S3/2 (Er3+) with the maximum value of 2.70 %K−1 at 288 K is improved tempestuously than the conventional TCELs, even larger than many other rare earth ion doped temperature sensors. The results presented in this work indicate that the transparent Er3+/Tm3+/Yb3+ tri-doped β-PbF2 GCs is a competitive dual-functional candidate with large range of color-tunable UCL and high thermosensitivity.

Enhanced mid-infrared emission in Er3+/Tm3+ co-doped tungsten-tellurite glasses

Transparent Er3+/Tm3+ co-doped tungsten-tellurite (TWL) glasses with variable Er3+ concentration were prepared by the conventional melt-quenching method. The samples prepared were investigated by differential scanning calorimetry (DSC), absorption spectra, up-conversion, near and mid-infrared emission and lifetime decays. DSC analyses indicates a high transition temperature (Tg) and a large value of △T. Enhanced 2.7 μm emission in Er3+/Tm3+ co-doped TWL glasses presents its superiority in mid-infrared application. Based on above emission spectra and lifetime decays, the energy transfer mechanism between Er3+ and Tm3+ ions was discussed. Tm3+ ions are an effective sensitization for 2.7 μm emission of Er3+ ions in this glass for its high energy transfer efficiency (83.6%). A comparative study on emission performance suggests that this Er3+/Tm3+ codoped TWL glass is a competent candidates for mid-infrared laser materials.

Emission color-tunable and optical temperature sensing properties of Er3+/La3+ co-doped (K0.5Na0.5)NbO3 optoelectronic transparent ceramic

Transparent Er3+/La3+ co-doped (K0.5Na0.5)NbO3 ceramic was prepared by pressureless sintering. The XRD result shows that it possesses high symmetrical pseudo-cubic perovskite structure without impurity phase. The ceramic owns fine grains with the average size of ∼350 nm, uniform grain distribution, low porosity and high density. The optical transmittance of 0.3-mm ceramic is up to ∼60% in the visible region. Additionally, the ceramic has good dielectric properties with the relaxor-like behavior. Under an excitation of 980-nm, the temperature-dependent up-conversion luminescent color of Er3+ is stable below 523 K and adjustable (changing from green to tangerine color as temperature increases) above 523 K. The ratio of red to green emission intensity with temperature can provide a non-contact luminescent route to roughly detect the phase transition of this ferroelectric ceramic. Furthermore, the fluorescence temperature sensing performance of the ceramic was investigated and the maximum sensitivity is 0.003/K at 380 K. Due to optical, PL and electrical properties, the transparent ceramic shows potential in the application of electro-optical coupling devices.

Enhanced up-conversion luminescence in transparent glass-ceramic containing KEr3F10:Er3+ nanocrystals and its application in temperature detection.

Transparent Er3+ doped glass-ceramics containing KEr3F10:Er3+ nanocrystals were prepared via the traditional melt-quenching technique. The micro-structures, optical properties and up-conversion luminescence behaviors of the Er3+ doped glass-ceramics were systemically studied using X-ray diffraction, absorption and up-conversion luminescence spectra. Under the excitation of a laser at 980 nm, the intensity of red emission of the glass-ceramics increases more than 70 times after heat treatment compared with that of the precursor glass ceramic. Moreover, the fluorescence intensity ratio of the thermally coupled energy levels (2H11/2 and 4S3/2) shows a good linear relationship with temperature and maintains relatively high sensitivities of 0.398% per K at 303–573 K, which indicates that the glass ceramics have promising applications in temperature detection.

Fabrication and microstructure characterizations of transparent Er:CaF2 composite ceramic

AbstractA novel layered transparent Er:CaF2 composite ceramic was proposed in the present study. Er:CaF2 nanoparticles were synthesized by a chemical coprecipitation method. The crystal structures and morphologies of synthesized nanoparticles were performed by X‐ray diffraction (XRD) and field emission scanning electron microscope (FE‐SEM) measurements, respectively. Transparent composite ceramic was fabricated by the combination of multistep dry pressing and hot‐pressed sintering method without any sintering aids or binders. The average grain size of 2% Er‐doped and 5% Er‐doped layers were about 30 and 55 μm, respectively. The thickness of interfacial between two different Er‐doped layers was 150‐200 μm. For a 1.5 mm thickness transparent Er:CaF2 composite ceramic, the optical transmittance reached 44.9% at 500 nm and 53.6% at 1200 nm. The luminescence spectra and thermal conductivities of transparent ceramic specimens were also discussed.

The effect of alkali metal ions on crystallization characteristics and luminescent properties of transparent Er3+-doped fluorosilicate glass-ceramics

In current work, transparent fluorosilicate glass-ceramics (GCs) containing NaYF4:Er3+ nanocrystals were successfully prepared by controlled heat treatment process. The thermal properties and crystallization characteristic temperatures were determined by the differential scanning calorimetry (DSC). The X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to confirm the formation of NaYF4 nanocrystals in glass matrix. Energy dispersive spectrometer (EDS) results and Judd-Ofelt (J-O) parameters analysis demonstrated the incorporation of Er3+ into NaYF4 nanocrystals. Intense 2.7 μm luminescence was observed in Er3+-doped GCs upon excitation with a 980 nm laser diode (LD). Furthermore, the effect of different alkali metals (Li+, Na+, K+) on crystallization characteristics and luminescent properties has been studied in detail, which indicates Li+ is the most favorable option for mid-infrared luminescence properties compared with Na+ and K+. The excellent spectroscopic characteristics suggest that the obtained GCs may be promising materials for mid-infrared fiber lasers.

Fabrication and characterization of Er, Nd codoped Y2O3 transparent ceramic: A dual mode photoluminescence emitter

The transparent Er, Nd co-doped Y2O3 ceramics with transparency ∼78% (in 500–2000 nm range without Fresnel's correction) were fabricated successfully. It involved nanoparticle synthesis by coprecipitation method and sintering of pellets under high vacuum condition. The crystalline phase, particle size and element composition were confirmed by X-ray diffraction, scanning electron microscope, energy dispersive X-ray fluorescence techniques, respectively. The upconversion luminescence mechanisms involving energy transfer and non-radiative relaxation were analyzed. It is expected that, the result evolved from this study will provide better understanding of upconversion mechanism involved in Er, Nd codoped host material. The emission at both 563 nm (Er3+:4S3/2 → 4I15/2) and 1064 nm (Nd3+:4F3/2 → 4I9/2) on 822 nm (Nd3+:4I9/2 → 4F5/2) excitation proves potential of the ceramic material for dual mode efficient emitter at room temperature.