Large Emission Cross Section Research Articles

Analysis of spectroscopic characteristics of Sm3+ ions doped gallium silicate glasses for orange-red LEDs

In this work, a variety of Sm3+ ions doped gallium silicate glasses have been made using the conventional melt quenching procedure, and characterized by X-ray diffraction, absorption spectrum, fluorescence spectrum, fluorescence decay curves, respectively. The density of the glass increases with the increase of the concentration of Sm3+ ions, and XRD shows that the samples are all amorphous glasses. Absorption spectra were used to determine the J-O intensity parameters (Ωλ, λ = 2, 4, 6), as well as the radiation transition probability(A), fluorescence branching ratio(βr), and radiation lifetime(τr) of Sm3+ ions at the 4G5/2 energy level. Under 403 nm excitation, the emission spectra show obvious emission peaks at 602 nm and 649 nm, corresponding to 4G5/2 → 6H7/2 and 4G5/2 → 6H9/2 transitions respectively. The B3 glass sample has the largest emission cross section(σem) at the 4G5/2 → 6H7/2 transition, with σem = 11.40 × 10−22 cm2. The color coordinates, color purity and color temperature values of all samples were calculated. The color purity of all samples varied in the range of 96.20%–99.14 %, with the relevant samples separating in the orange-red light region. The experimental results indicate that the glass samples have a potential application prospect in the field of orange-red LEDs.

2.7μm luminescence and structural properties of Er3+-doped fluorotellurate glass

In this paper, the thermal properties and internal structures of fluorotellurate glasses with different concentrations of TeO2 were studied. Glass samples with a concentration of 30mol% TeO2 were doped with different concentrations of Er3+ (1,2, 3,3.5,4,4.5,5mol%) and their luminescence characteristics were analyzed. The fluorotellurate glass possess high infrared transmittance (93 %), thermal stability (ΔT>110 °C), and low phonon energy (821 cm−1). Er3+ doped fluorotellurate glass exhibits high fluorescence lifetime of 4I11/2 level (1.59 ms), large emission cross-section (5.98 × 10−21cm2), and achieves a quantum efficiency of up to 30 %. These experimental findings suggest promising prospects for the utilization of Er3+ doped fluorotellurate glass in 2.7 μm laser applications.

Kilohertz-linewidth and low-threshold single-frequency all-fiber laser utilizing self-developed Nd3+-doped fluoro-sulfo-phosphate fiber.

Compared to Nd: YAG lasers, Nd3+-doped fiber lasers offer superior beam quality, compactness, and heat dissipation, especially in generating single-frequency lasers, which holds great promise for applications in optical atomic clocks, quantum computing, and high-precision bio-photonic imaging. In this study, theoretical simulations of the local environment and experimental analyses on the luminescent characteristics of what we believe to be a novel Nd3+-doped fluoro-sulfo-phosphate (FSP) laser glass were performed to mitigate the concentration and hydroxyl quenching effects. Based on that, a highly Nd3+-doped (4 mol%) FSP fiber with a large emission cross-section (3.24 × 10-20 cm2), wide bandwidth (33.7 nm), long lifetime (354 µs), and high gain coefficient (4.24 dB/cm) was designed. Utilizing this fiber, a 1065 nm SFFL with a low pump threshold of 18 mW, a narrow linewidth of 6.5 kHz, and a 0.9 µm compact all-fiber laser were demonstrated, highlighting the potential of Nd3+-doped FSP fiber in high-performance fiber lasers.

Design of Fiber Laser Based on Erbium-ion

Erbium ions (Er3+) exhibit good characteristics of fiber lasers in the 1500-1550 nm band, including three-level systems, high tilt efficiency, and large emission cross sections. This article focuses on studying the spectral characteristics of erbium ions, simulating the power propagation equation of erbium-doped ion fiber lasers, and calculating the pump power threshold and output power. The findings of the simulation indicate that the laser begins to produce 10 W of pump optical power. The laser power hits 34.38 W and the oblique power is determined to be 38.20% as soon as the pump power exceeds 100 W. Experimental results show that when pump light propagates forward, the forward propagation power of the pump light will weaken, the forward propagation power of the signal light will increase, the reverse propagation of the signal light will weaken and the reverse propagation of the pump light will Transmission will also weaken, with directional transmission remaining largely unchanged. This study carried out numerical simulations on the experimental parameters of the fiber laser doped with Er3+and finally obtained the output power of pump light and signal light under these conditions, providing better data support for the preparation of 1500-1550 nm fiber laser doped with erbium ion.

A novel Nd3+-doped fiber fabricated by curable nanocomposites for 916 nm laser

In this work, a novel Nd3+-doped silica fiber preform was fabricated by the UV-curable nanocomposite technology combined with the solution doping method. The preform sample had a great homogeneity with a doping concentration of 1.14 wt% Nd3+ ions and 2.51 wt% Al3+ ions. The obtained Nd3+-doped core glass provided a relatively large emission cross section (∼0.84 pm2) and a long lifetime (373 μs) of 916 emission. On this basis, by using an 808 nm laser diode as the pump source, lasing at 916 nm was achieved from a 4 cm long fabricated Nd3+-doped silica fiber, with the corresponding slope efficiency of ∼13.6 %. Notably, only 2 cm-short created fiber alone was enabled for 916 nm lasing generation. Our results indicated that the created Nd3+ doped fiber by the novel approach has unique advantages and potential for compact short-cavity 0.9 μm laser applications.

Crystal Structure and Optical Characteristics of K2Nd2O(BO3)2

A rare earth oxyborate crystal K2Nd2O(BO3)2 has been grown by means of high temperature solution method for the first time. It crystallizes in monoclinic P21/c (No. 14) space group, and the lattice parameters are a=11.318(6) Å, b=6.575(4) Å, c=10.689(6) Å, β=117.062(12)°, and Z=4. The absorption spectrum, emission spectrum, and fluorescence lifetime of K2Nd2O(BO3)2 have been evaluated, and the foundational spectral parameters have been analysed according to the Judd‐Ofelt theory. The high concentration of activated ions (1.13×1022 ions/cm3), large absorption coefficient (87.63 cm‐1), long fluorescence lifetime (91.2 μs), and large emission cross section (2.03×10‐20 cm2) of K2Nd2O(BO3)2 suggest its potential applications of microchip lasers.

Enhanced 2 μm emission behavior and energy transfer in Ho3+/Yb3+ co-doped bismuth-tellurite fiber-core glasses by CeO2

Ho3+/Yb3+ co-doped and Ho3+/Yb3+/Ce3+ tri-doped 85TeO2–5Bi2O3–10ZnO glasses were synthesized by the melt-quenching method. The structural and spectral properties were investigated comprehensively according to Raman, absorption, and fluorescence spectra. By evaluating the energy transfer process, the 2 μm emission behavior has been enhanced effectively with the introduction of a glass network modifier (CeO2), which can be ascribed to the population of Ho3+: 5I7 accelerated by cross-relaxation (CR) between Ho3+ and Ce3+. A large emission cross-section (1.11 × 10−20 cm2) and gain coefficient (2.12 cm−1) have been obtained of Ho3+ at around 2 μm band in TBZHYC2 glass, where a significant advancement has been achieved compared with the glass fiber core without CeO2. Moreover, the energy transfer mechanisms between Ho3+/Yb3+ and Ho3+/Ce3+ were quantitatively analyzed based on a spectral overlap method. As mentioned above, Ho3+/Yb3+/Ce3+ tri-doped bismuth-tellurite glasses are potentially competitive and applicable in the field of 2 μm band infrared fiber lasers as a kind of novel laser glass.

Singly Ho3+-doped tantalum tellurite glass and optical fiber for 2 μm fiber lasers

Singly Ho3+-doped TeO2–Ta2O5–ZnO (TTZ) glass and optical fiber for 2 μm fiber lasers have been investigated. The glass-forming region of the ternary TTZ glass system is determined to study its glass-forming ability and to select an appropriate glass matrix for doping Ho3+ ions. Upon the excitation of a 1940 nm laser diode (LD), an intense emission at 2.06 μm with a full width at half maximum (FWHM) of 61 nm is observed from the Ho3+-doped TTZ glass. The measured lifetime of the Ho3+: 5I7 level in TTZ glass shows a gradual decrease from 3.5 to 0.98 ms as the dopant concentrations increase from 0.2 to 2 mol%. A large emission cross-section (σeMC ∼ 4.56 × 10−21 cm2) and figure of merit (FOM, ∼ 6.83 × 10−24 cm2·s) are obtained. The Ho3+-doped TTZ glass is further fabricated into an optical fiber with an average transmission loss of 0.12 dB/cm at 1310 nm. The results show that singly Ho3+-doped TTZ glass and optical fiber are promising candidates for efficient 2 μm fiber lasers.

Structure and fluorescence characteristics in highly Dy3+ doped tellurite-fluoride glass for white light fiber lasers

High concentration Dy3+ doped 75TeO2-25YF3-xDyF3 (where x = 8, 10, 12, 14 mo1%) were synthesized by a melt-quenching method. Raman spectra and oscillator strength were utilized to evaluate the structural of glass and radiation properties with differing DyF3 concentrations. The maximum phonon energy of the glass is about 770 cm-1. Ω6 and χ are 3.5 and 0.51 when DyF3 concentration reaches 10 mol%, indicating that the activated ions in the glass material system have a wide fluorescence bandwidth and excellent stimulated emission characteristics. The yellow/blue value enhance with the addition of high concentrations of DyF3, which may be due to the depolymerization of [TeO4], gradually converting into [TeO3+1] and [TeO3], destroying with the local coordination environment and inverting Dy3+ symmetry. Furthermore, under the excitation wavelength of 350 nm, the TYDF2 glass obtained relatively large emission cross-section (35.53 × 10−22 cm2) and gain coefficient (5.88 cm−1) at 4F9/2 → 6H13/2. The CIE coordinates are in the range of white light, and the CCT values are between 4200 and 4400 K. The results show that highly Dy3+ doped tellurite-fluoride glasses prepared in this way have the potential as a gain materials for white light fiber lasers.

Fabrication of sub-micrometer sized Er:CaF2 transparent ceramics for eye-safe lasers

The 1 at.% Er:CaF2 transparent ceramics were prepared by the air pre-sintering and hot isostatic pressing (HIP) using nano-powders synthesized by the co-precipitation method. The influence of pre-sintering temperature and HIP post-treatment on the density, microstructures, optical and photoluminescence properties of Er:CaF2 ceramics were investigated. After HIP post-treatment (650 °C × 2 h, 100 MPa Ar), the pores in the pre-sintering ceramics were gradually eliminated and high transparency was achieved. The maximum in-line transmittance of the HIPed 1 at.% Er:CaF2 reaches 90.5% at 1600 nm (2.8 mm thickness) when the pre-sintered temperature is 625 °C.The absorption cross section was calculated. The strong absorption peak at 1530 nm reveals an unfavorable infrared emission. The main emission peak at 1530 nm, which is derived from the 4I13/2 → 4I15/2 transition of Er3+, can be observed under excitation of 980 nm. Owing to the long lifetime of 4I13/2 (32.3 ms) and large emission cross section, the 1 at.% Er:CaF2 transparent ceramics have great potential to achieve a good NIR laser performance in the 1.5 μm region.

Strong and broadband 2.7 μm fluorescence of Yb3+/Er3+ co-doped ZnO modified tungsten tellurite glasses for broadband mid-infrared optical amplifiers and tunable fiber lasers

Strong and broadband 2.7 μm fluorescence with effective emission linewidth of 140.4 nm has been achieved in 1 mol% Yb2O3 and 1 mol% Er2O3 co-doped ZnO modified tungsten tellurite glass under an excitation from a 980 nm laser diode. The influences of Yb3+ concentration on 2.7 μm spectroscopic properties of Yb3+/Er3+ co-doped ZnO modified tungsten tellurite glasses were analyzed by absorption spectra, emission spectra and lifetime measurement. Long lifetime of 4I11/2 level (649.4 μs), high spontaneous radiative transition probability (65.1 s−1), large emission cross section (8.27 × 10−21 cm2) and figure of merit (5.37 × 10−24 cm2s) near 2.7 μm ensure intense 2.7 μm emission. Furthermore, the energy transfer coefficients between Yb3+ and Er3+ ions are quantitatively determined to explain the reinforcement of 2.7 μm fluorescence. Therefore, Yb3+/Er3+ co-doped ZnO modified tungsten tellurite glasses with better 2.7 μm spectroscopic performances are predominant candidates in constructing broadband mid-infrared optical amplifiers and tunable fiber lasers.

Investigation of Er3+-Doped Phosphate Glass for L+ Band Optical Amplification

In this work, Er <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> -doped phosphate glass with good flatness of the emission spectrum of the L+ band was prepared by optimizing the content of BaO. The absorption and emission spectra were measured. Increase of BaO content is conducive to the broadening of the emission spectrum in the L+ band. The dependence of flatness with Raman intensity has been shown by linear fitting. The results show that B31 sample has best flatness of the emission spectrum in the L+ band. It is showed that the largest emission cross-section at 1630 nm is 0.0529 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-20</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and higher than other Er <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> -doped phosphate glass. Decay curves of the <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13/2</sub> level were measured and the longest fluorescent lifetime is 10.18 ms and longer than other glass except germinate glass. The broadening of the Er <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> -doped phosphate glass spectrum of the L+ band has been achieved successfully, which provides a reference for the material of optical amplifiers.

Visible to infrared down conversion of Er3+ doped tellurite glass for luminescent solar converters

A series of tellurite glasses having the composition70TeO2–20ZnO–(10-x)Nb2O5 (in mol%) doped with Er3+ ion (x = 0.5, 1.0, 1.5, 2.5, 3, 3.5 and 4 mol% respectively) was synthesized using the melt quenching route. Based on the Raman analysis and Differential Scanning Calorimetry, the produced glasses exhibited low-phonon (772 cm−1) energy and good thermal stability (147 °C), respectively. The X-ray (XR) diffraction proved the amorphous state of the synthesized glasses, which highlights the high quality of the obtained glass materials. The impact of Er2O3 content on the local structure around erbium ions was investigated via Judd-Ofelt theory. Various radiative parameters such as the quality factors (χ), the branching ratios (β), the quantum efficiencies (η) and radiative lifetimes (τR) have been reported and discussed. The Down-conversion (DC) energy-process in the Er3+ ions was analyzed using an excitation wavelength of 488 nm and the different mechanisms involved in the 1.53 µm emission are discussed. The effect of erbium content on the measured lifetime of the 4I13/2state was analyzed according the M. Inokuti and F. Hirayama (I-H) model. For high concentrations of Er2O3 oxide, the obtained results showed an efficient energy transfer between Er3+ ions, which may cause the luminescence quenching and the reduction in radiative parameters of the 4I13/2 → 4I15/2 transition at 1.53 µm. While the addition of Er2O3 oxide at low content up to a concentration of 4.211020 cm−3 showed that this glass possessed high quantum efficiency (91%), large emission cross section of about 9.1 10−21 cm2 and effective bandwidth exceeding 100 nm attributed to the 1.53 µm emission, which makes the proposed tellurite glass highly promising in many photonic applications, especially for the design of luminescent solar concentrators (LSC) for bandgap solar cells in the range of 0.7–0.9 eV.

∼2 μm fluorescence and energy transfer characteristics in a highly Tm3+-doped bismuthate glass based on Al2O3 adjustment

In this paper, the glass network of a newly developed bismuthate glass was adjusted and analyzed by changing the Al2O3 content, thus effectively increasing the doping concentration of Tm3+. The fundamental physical and thermal properties including density, molar volume, refractive indices, and characteristic temperatures were systematically investigated, suggesting the B2O3/Al2O3 anomaly ratio of the prepared host glass is 35%/10%. Various glass network units were found in the host glasses, so that the flexibility of the glasses was enhanced, which is favorable for highly and homogeneously doping of Tm3+ ions. A highly Tm3+-doped bismuthate glass with a concentration of 20.5 × 1020 ions/cm3 was prepared without quenching. Radiative parameters of the presented glass were determined from absorbance spectra. Moreover, relatively large emission cross-section (5.29 × 10−21 cm2) and gain coefficient (10.87 cm-1) were achieved in the prepared highly Tm3+-doped bismuthate glass. Finally, the microparameters for energy transfer processes were calculated by a spectral overlap method. Results show that the presented highly Tm3+-doped bismuthate glass has ideal potential for high gain fibers in ∼2 µm band.

Spectroscopic properties of Er3+-doped fluoroindate glasses

The optical and thermal properties of a new class of fluoroindate glass with different erbium contents were investigated via Raman, transmission, and fluorescence spectroscopies, fluorescence decay curve analysis, and differential scanning calorimetry. The strength parameters of the samples were calculated using the Judd–Ofelt theory. The mid-infrared luminescence properties of erbium-doped fluoroindate glasses were studied, and a strong emission at 2.7 μm was obtained. Compared with the traditional ZBLAN glass, this glass has excellent emission properties, especially a longer fluorescence lifetime (7.09 ms) and larger emission cross-section (6.95 × 10−21 cm2) at 2.7 μm. The results indicate that fluoroindate glass is an attractive host for mid-infrared lasers and as a gain medium for optical amplifier applications.

Kerr-lens mode-locked Yb:LuAG ceramic thin-disk laser.

A Kerr-lens mode-locked (KLM) thin-disk laser with Yb:LuAG ceramic was demonstrated. Yb:LuAG ceramic is an attractive material for high-power lasers due to its high thermal conductivity and large emission cross section. The highest output power of 17 W with a pulse duration of 130 fs was achieved. Moreover, the pulse duration of 88 fs was also obtained with a high-Q factor cavity. To the best of our knowledge, this is the first demonstration of a KLM thin-disk laser based on Yb:LuAG, including both ceramic and single crystal. The results show the usefulness of ceramic thin disks for high-power ultrashort pulse laser sources.

Spectroscopic properties of ErF3 doped tellurite–gallium oxyfluoride glass for ∼3 μm laser materials

ErF3-doped TeO2–Ga2O3–BaF2–AlF3–Y2O3 (TGBAY) glasses with high fluorescence efficiency and a high thermal damage threshold were developed for potential mid-infrared fiber laser applications. A model 2.7-μm fiber laser based on this material was analyzed using rate and propagation equations. Under 808 and 980 nm laser pumping, fluorescence emissions with central wavelength at 1.55 and 2.73 μm were detected. Based on the Judd–Ofelt (J–O) theory, the intensity parameters (Ωλ, λ = 2, 4, and 6) and radiative transition property were calculated and characterized through absorption and emission spectra. The results indicated that tellurite–gallium oxyfluoride glass had a high glass transition temperature (Tg, ∼391 °C), large emission cross sections at 1.55 μm (6.32 × 10−21 cm2) and 2.73 μm (9.68 × 10−21 cm2) as well as a longer fluorescence lifetime (6.84 ms at 1.55 μm and 262 μs at 2.73 μm) relative to the conventional Er3+-doped tellurite glass. The temperature dependence of the emission spectra indicated that TGBAY-2Er glass was more favorable to achieve infrared emission at low temperatures. Numerical simulation revealed the feasibility of achieving a ∼2.7 μm fiber laser operation based on the developed Er3+-doped tellurite–gallium oxyfluoride glass fiber.

Enhanced 3.9 µm emission from diode pumped Ho3+/Eu3+ codoped fluoroindate glasses.

The use of Eu3+ codoping for enhancing the Ho3+:5I5→5I6 emission in fluoroindate glasses shows that Eu3+ could depopulate the lower laser state Ho3+:5I6 while having little effect on the upper state Ho3+:5I5, resulting in greater population inversion. The Ho3+/Eu3+ codoped glass has high spontaneous transition probability (6.31s-1) together with large emission cross section (7.68×10-21cm2). This study indicates that codoping of Ho3+ with Eu3+ is a feasible alternative to quench the lower energy level of the 3.9 µm emission and the Ho3+/Eu3+ codoped fluoroindate glass is a promising material for efficient 3.9 µm fiber lasers.

2.86 μm emission and fluorescence enhancement through controlled precipitation of ZnTe nanocrystals in DyF3 doped multicomponent tellurite oxyfluoride glass

Tellurite oxyfluoride glasses with composition of 71TeO2-10ZnO-10BaF2-4K2O-3Nb2O5-2TiO2 doped with different concentrations of DyF3 (0.3, 0.4, 0.5, 0.7, 1 wt%) were prepared by melt-quenching method under dry O2 atmosphere. Under 808 nm laser pumping, infrared (IR) fluorescence emission with central wavelength of 2.86 μm was detected. Basing on the Judd-Ofelt (J-O) theory, the intensity parameters (Ωλ, λ=2, 4 and 6) and radiative property were calculated and characterized through the transmission and fluorescence spectra. The tellurite oxyfluoride glass had high thermal stability and large emission cross-section at 2.86 μm (7.82 × 10−21 cm2). DyF3 doped tellurite oxyfluoride glass ceramic were prepared via in-situ crystallization of ZnTe nanocrystals through heat treatment to ameliorate the surrounding environment of rare earth (RE) ions. The tellurite oxyfluoride glass ceramic prepared by heat treatment at 390°C had great enhancement in 2.86 μm fluorescence intensity (about 7 times), longer fluorescence lifetime (126 μs), indicating that the in-situ crystallization method may be helpful for exploring tellurite based high gain laser glass.

Surface radiation-regulation effect in Eu(BA)3Phen doped polyacrylonitrile nanofibers

Electrospun nanofibers of Eu(BA)3Phen doped polyacrylonitrile (PAN) have been prepared and the surface radiation-regulation effect of flexible fibers is revealed. Fluorescence contrast between bulks and nanofibers confirmed that the fibrosis process facilitated spectral reshaping and enhanced energy transfer efficiency of ligands to rare earth ions. Due to the enhanced surface radiation-regulation effect, the quantum efficiency of Eu(BA)3Phen/PAN nanofibers remains on an upward tendency as Eu(BA)3Phen content increasing, and the maximum quantum efficiency of fibers reaches to 86.7%. Large emission cross-section and high radiation transition probability for 5D0 → 7F2 of Eu3+ reach up to 4.043 × 10−21 cm2 and 518.79 s−1, respectively, which indicates that the europium-complexes/PAN nanofibers possess great emissive ability. Accordingly, the nano-sized rare-earth fluorescence materials with high quantum efficiency and excellent flexibility obtained by electrospun fibrosis compensate the brittle defects of bulks, which provides a breakthrough in developing light-converting materials.