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1D semiconductors with atomically precise edge and well‐controlled width hold significant promise as channel materials for next‐generation electronics. Here a method to fabricate the narrowest zigzag‐edged bismuth phosphide (BiP) nanoribbons (NRs) is presented, achieving widths of three atoms (≈0.7 nm), through molecular beam epitaxy on bismuthene in a wide P coverage range. Using scanning tunneling microscopy and first‐principles calculations, it is revealed that these BiP NRs exhibit a blue‐phosphorene‐like structure, with a theoretical bandgap of 0.38 eV. Notably, first‐principles calculations reveal spin‐polarized states located on the zigzag edges, presenting an option for spintronics applications. Formation of these uniform BiP NRs is attributed to tensile strain from lattice‐registry confinement. During epitaxial growth, P clusters act dually as feedstock and catalysts, suggesting a self‐catalyzed growth mechanism. The bottom‐up strategy offers an effective approach for the atomically precise fabrication of 1D BiP NRs, paving the way for the creation of diverse low‐dimensional binary materials with tailored chemical and electronic properties, facilitated by selecting suitable elemental 2D materials as substrates. [ABSTRACT FROM AUTHOR]

Background: Inflammation and immune status are correlated with the severity of major depressive disorder (MDD).The purpose of this study was to establish an optimization model of peripheral blood parameters to predict the severity of MDD. Methods: MDD severity in the training and validation cohorts (n = 99 and 97) was classified using the Hamilton Depression Scale, Thirty-eight healthy individuals as controls. Significant severity-associated factors were identified using a multivariate logistic model and combined to develop a joint index through binary logistic regression analysis. The area under the receiver operating characteristic curve (AUC) was used to identify the optimal model and evaluate the discriminative performance of the index. Results: In the training cohort, lower CD4+/CD8+ T cell ratio, albumin level, and a higher monocyte percentage (M%) were significant as operating sociated with severe disease (P < 0.05 for all). The index was developed using these factors and calculated as CD4+/CD8+ T cell ratio, albumin level, and M%, with a sensitivity and specificity of 90 and 70%, respectively. The AUC values for the index in the training and validation cohorts were 0.85 and 0.75, respectively, indicating good discriminative performance. Conclusion: We identified disease severity-associated joint index that could be easily evaluated: CD4+/CD8+ T cell ratio, albumin level, and M%. [ABSTRACT FROM AUTHOR]

In this work,60TeO 2 -(35-x)ZnO-xNb 2 O 5 –5SrF 2 -0.5Dy 2 O 3 glasses was prepared to use a high-temperature melting method, where x represents the Nb 2 O 5 content (x = 0,5,7.5,10).Raman spectra studies revealed that increasing the concentration ratio of Nb 2 O 5 to TeO 2 resulted in the gradual transformation of [TeO 3 ] and [TeO 3+1 ] units in the glass network to [TeO 4 ] units. This transformation also enhanced the stability of the network structure. The emission peaks of the samples were observed at 481 nm (blue), 576 nm (yellow), and 663 nm (red), which is crucial for white light materials. The luminescent intensity increased with the increase of Nb 2 O 5 concentration, reaching its maximum at 7.5% mol. The CIE 1931 chromaticity coordinates fell within the range of white light, with corresponding color temperatures ranging from 5063 K to 5877 K. All the results show that the fluorescent materials used in high-brightness illumination can be obtained by adding an appropriate amount of Nb 2 O 5 to Dy3+-doped tellurate glass. [ABSTRACT FROM AUTHOR]

Since the discovery of graphene, 2D materials have attracted significant attention for their unique properties. Monoelemental 2D materials (ME2DMs) are of particular interest because of their superiority in synthetic exploration, excellent mobility, and wide range of band gaps over other 2D compounds. Substantial efforts are devoted to fabricate high‐quality materials through various substrates and reveal the growth mechanism at the atomic scale. In this review, the recent progress in the preparation of these ME2DMs is explored, the roles of different substrates is highlighted, and the challenges of and perspectives on their heterostructures is discussed. [ABSTRACT FROM AUTHOR]

One-dimensional (1D) zigzag tellurium (Te) wires on an alloyed Cu2Sb (111) surface are produced and characterized by combining molecular beam epitaxy and high-resolution scanning tunneling microscopy, respectively. These 1D Te wires with zigzag shapes exhibit a uniform width and well-defined periodicity grown in registry on a Cu2Sb (111) substrate. Density functional theory (DFT) calculations revealed a remarkable bandgap of 0.3 eV induced by spin–orbit coupling. Interestingly, the resulting Te wires became metallic on the substrate, as confirmed by scanning tunneling spectroscopy and DFT. The present study provides a platform for constructing periodic atomic wires on alloyed surfaces, which may be extended further to integrate them into circuits. [ABSTRACT FROM AUTHOR]

A novel double‐cladding Ho3+/Tm3+ co‐doped Bi2O3–GeO2–Ga2O3–BaF2 glass fiber, which can be applied to a 2.0‐μm infrared laser, was fabricated by a rod‐tube drawing method. The thermal properties of the glass were studied by differential scanning calorimetry. It showed good thermal stability and matching thermal expansion coefficient for fiber drawing when Tx−Tg > 193°C and the maximum difference of the thermal expansion coefficient is 3.55 × 10−6/°C or less. The 2.0‐μm luminescence characteristics were studied using the central wavelength of 808 nm pump light excitation. The results show that when the concentration ratio of Ho3+/Tm3+ reaches 0.5 mol%:1.0 mol%, the maximum fluorescence intensity was obtained in the core glass, the emission cross section reached 10.09 × 10−21 cm2, and the maximum phonon energy was 751 cm−1. In this paper, a continuous laser output with a maximum power of 0.986 W and a wavelength of 2030 nm was obtained using an erbium‐doped fiber laser as a pump source in a 0.5 m long Ho3+/Tm3+ co‐doped glass fiber. In short, the results show that Ho3+/Tm3+ co‐doped 36Bi2O3–30GeO2–15Ga2O3–10BaF2–9Na2O glass fiber has excellent laser properties, and it is an ideal mid‐infrared fiber material for a 2.0‐μm fiber laser with excellent characteristics [ABSTRACT FROM AUTHOR]

Combinations of phosphorus with main group III, IV, and V elements are theoretically predicted to generate 2D binary phosphides with extraordinary properties and promising applications. However, experimental synthesis is significantly lacking. Here, a general approach for preparing 2D binary phosphides is reported using single crystalline surfaces containing the constituent element of target 2D materials as the substrate. To validate this, SnP3 and BiP, representing typical 2D binary phosphides, are successfully synthesized on Cu2Sn and bismuthene, respectively. Scanning tunneling microscopy imaging reveals a hexagonal pattern of SnP3 on Cu2Sn, while α‐BiP can be epitaxially grown on the α‐bismuthene domain on Cu2Sb. First‐principles calculations reveal that the formation of SnP3 on Cu2Sn is associated with strong interface bonding and significant charge transfer, while α‐BiP interacts weakly with α‐bismuthene so that its semiconducting property is preserved. The study demonstrates an attractive avenue for the atomic‐scale growth of binary 2D materials via substrate phase engineering. [ABSTRACT FROM AUTHOR]

The double‐cladding Er3+/Yb3+ co‐doped bismuth germanium gallate microstructure fiber of large mode, with the core diameter of 30.6 μm, the inner cladding air pore diameter of about 3.06 μm and a lattice constant of 10.2 μm is prepared by a bundle‐drawing method. The spectral characteristics at 975 nm wavelength were studied and the results show that the maximum fluorescence intensity and the high gain quality factor of the fiber core glass can be obtained when the molar ratio of Er3+ to Yb3+ is 0.5%:2% and its emission cross section is up to 10.9 × 10−21 cm2. A stable laser output with a maximum power of 51.16 mW and a wavelength of 2710 nm was obtained in a microstructure optical fiber with a length of 160 mm employing a independently constructed fiber laser with a cascade structure, whose pump light power was 561 mW, the slope efficiency was 6.89%, the effective mode field area is about 576 μm2 and the beam quality factor M2 < 1.02. The double‐cladding Er3+/Yb3+ co‐doped bismuth germanium gallate microstructure fiber of large mode has excellent laser properties and is an ideal optical fiber material for the development of the 3.0 μm laser. [ABSTRACT FROM AUTHOR]

• The evolution of luminescence behavior and structure has been investigated by modifying network topology based on the substitution of TeO 2 with WO 3. • Micro-parameters of the energy transfer process in Ho3+/Yb3+ have been enhanced by introducing WO 3. (C D-A increased from 0.36 × 10−40 cm6/s to 1.11 × 10−40 cm6/s). • Emission section of Ho3+: 5I 6 → 5I 7 is 1.51 × 10−20cm2 (2884 nm), which increased 11.85% compared with those without WO 3. Ho3+/Yb3+ co-doped bismuth-tellurite glasses (TeO 2 -Bi 2 O 3 -ZnO) have been investigated systematically according to the Raman, absorption, and mid-infrared luminescence spectra, contraposing 3 μm band. The evolution of luminescence and structure has been explored by modifying network topology based on the substitution of TeO 2 with WO 3 when the optimal concentration ratio of Ho3+/Yb3+ was determined in TBZ glass. The results show that WO 3 entered the glass structure network as [WO 4 ] and [WO 6 ] units, contributing to the content of bridging oxygen and network connectivity increased, which can be enhanced effectively the luminescence properties. The gain cross-section is 1.51 × 10−20 cm2 (2884 nm) increasing by 11.85% compared with the glass without glass network modifiers. Moreover, the energy transfer micro-parameters have been calculated based on a spectral overlap method. The C D-A was augmented from 0.36 to 1.11 × 10−40 cm6/s. As mentioned above, the bismuth-tellurite glasses have the potential as the gain materials for mid-infrared fiber lasers. [ABSTRACT FROM AUTHOR]

Monolayer iron oxides grown on metal substrates have widely been used as model systems in heterogeneous catalysis. By means of ambient-pressure scanning tunneling microscopy (AP-STM), we studied the in situ oxidation and reduction of FeO(111) grown on Au(111) by oxygen (O2) and carbon monoxide (CO), respectively. Oxygen dislocation lines present on FeO islands are highly active for O2 dissociation. X-ray photoelectron spectroscopy measurements distinctly reveal the reversible oxidation and reduction of FeO islands after sequential exposure to O2 and CO. Our AP-STM results show that excess O atoms can be further incorporated on dislocation lines and react with CO, whereas the CO is not strong enough to reduce the FeO supported on Au(111) that is essential to retain the activity of oxygen dislocation lines. [ABSTRACT FROM AUTHOR]

High concentration Dy3+/Tm3+ co-doped fluorotellurite glasses were prepared using melt-quenching method. The glass structure, spectral properties, and lifetime decay curves of the glasses were characterized. The results showed that the chromaticity coordinates changed due to the introduction of Tm3+ while the Dy3+ content remained constant. By capitalizing on the overlap region in excitation spectra between Dy3+/Tm3+ and exciting the samples at 355 nm, the resulting chromaticity coordinate (0.308, 0.318) closely resembled that of standard white light. This desirable outcome was achieved by adjusting the composition of Dy3+ and Tm3+ to 6.0 mol% and 3.0 mol% respectively. Furthermore, the addition of Tm3+ induced a gradual shortening of the fluorescence lifetimes of Dy3+, suggesting an efficient energy transfer process occurring between the two ions. In the investigation, the utilization of the Inokuti-Hirayama (I-H) model revealed that the alteration in lifetime decay curves displayed a proximity to S = 6. This implies that the primary mechanism implicated in energy transfer was the interaction of electric dipole-dipole. The results of this study have practical application significance for exploring high-quality white light emission and display devices. • High concentration of Dy3+/Tm3+ doped fluorotellurite glass. • The coordinate value was close to the standard white light. [ABSTRACT FROM AUTHOR]

• The ∼ 2 μm emission intensity of Tm3+ doped bismuth glass can be enhanced by the introduction of Ga 2 O 3. • Bismuth glasses process excellent thermal stability for fiber drawing. • BBG3 has a broad emission band (Δλ eff = 251.42 nm) and gain coefficient (10.89 cm−1). The influence of B 2 O 3 ↔ Ga 2 O 3 substitution on the ∼ 2 μm emission and gain properties of Tm3+-doped Bi 2 O 3 -B 2 O 3 -BaF 2 glasses was investigated by absorption, fluorescence, and Raman spectroscopy. It is shown that the thermal stability was enhanced as Ga 2 O 3 replaces the B 2 O 3 component gradually, while [GaO 4 ] and [BO 4 ] units enter the network. When the concentration of Ga 2 O 3 reaches 8 mol% (BBG3 glass), the maximum gain coefficient at ∼ 2 μm reaches 10.89 cm−1, which is larger than other glasses. Enhanced ∼ 2 μm emission and gain properties can be obtained by content Ga 2 O 3 with the choice of 15 mol%. The W ET of Tm3+ was calculated to reach 2051.7 × 10-20 cm3/s, indicating that an effective cross-relaxation process can be obtained. The Tm3+ doped bismuth glasses show potential as ∼ 2 μm fiber amplifiers. [ABSTRACT FROM AUTHOR]

Recently, 2.7 µm lasers have attracted much attention because of their wide applications in remote sensing, and medical laser surgery. The effect of Bi 2 O 3 ↔ BaF 2 substitution in the Er3+ doped Bi 2 O 3 -GeO 2 -BaF 2 glasses on physical and 2.7 µm emission properties have been studied. Under the excitation of 976 nm LD, an intense and broad 2.7 µm emission originating from the 4I 11/2 → 4I 13/2 transition of Er3+ was observed. BaF 2 was found to enter the glass network as Ba2+ and F−, which may contribute to a reduction in the bridge oxygen content. The 1.55 µm emission was attenuated and the 2.7 µm emission was enhanced due to the combined effect of F− reducing the OH− content of the glass and Ba2+ expanding the distance between Er3+ ions. Furthermore, the peak emission cross-section is calculated to be 12.9 × 10−21 cm2. The Er3+ doped Bi 2 O 3 -GeO 2 -BaF 2 glasses show potential as broadband mid-infrared emission gain material. [ABSTRACT FROM AUTHOR]

In this work, the glass network has been tailored by introducing the modifier WO 3 when a Ho3+/Yb3+ co-doped bismuth-tellurite glass composition was designed. The physical, absorption, emission, structure, and gain characteristics of the glasses with the different contents of WO 3 were investigated comprehensively based on various tests and analytical methods such as absorption spectra, fluorescence spectra, Raman spectra, and J-O theory. The results show that both the optical band gap and the bridge oxygen content are enhanced remarkably while the substitution of TeO 2 by WO 3 , accelerating the transition from [TeO 3 ] to [TeO 4 ] units. Simultaneously, the value of Ω 6 reached the maximum of 2.26×10-20 cm2 when the WO 3 is equal to 10 mol%, indicating that the Stark splitting of Ho3+: 5I 7 energy level is the weakest. The optimal FWHM and the gain coefficient are 143.3 nm and 2.22 cm-1, respectively. Furthermore, a blue shift of the central wavelength in absorption and emission peaks can be observed at the 2 μm band. As mentioned above, the bismuth-tellurite glass prepared is an ideal gain material that can realize a wider spectra span. [ABSTRACT FROM AUTHOR]

• The 2 μm band emission properties of bismuth-tellurite glass can be enhanced by energy transfer possess modified. • The topology structure units of the bismuth-tellurite glass can be investigated comprehensively by using Gaussian fitting. • The emission cross-section of Ho3+: 5I 7 → 5I 8 in TBZHYC2 glass has been enhanced by about 10 % compared with TBZ glass (from 1.01 × 10−20 cm2 to 1.11 × 10−20 cm2) when the concentration of CeO 2 is 0.3 mol%. Ho3+/Yb3+ co-doped and Ho3+/Yb3+/Ce3+ tri-doped 85TeO 2 –5Bi 2 O 3 –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 (CeO 2), which can be ascribed to the population of Ho3+: 5I 7 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 CeO 2. 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. [ABSTRACT FROM AUTHOR]

Ho3+/Tm3+ co-doped 50TeO2-25GeO2-3WO3-5La2O3-3Nb2O5-5Li2O-9BaF2 glass fiber is prepared with the rod-tube drawing method of 15 μm core diameter and 125 μm inner cladding diameter applied in the 2.0 μm-infrared laser. The 2.0 μm luminescence properties of the core glass are researched and the fluorescence intensity variation for different Tm3+ doping concentration is systematically analyzed. The results show that the 2.0 μm luminescence of Ho3+ is greatly influenced by the doping concentration ratio of Ho3+ to Tm3+ and that the maximum fluorescence intensity of the core glass can be obtained and its emission cross section can reach 0.933 × 10−21 cm2 when the sensitized proportion of holmium to thulium is 0.3 to 0.7 (mol%). Simultaneously, the maximum phonon energy of the core glass sample is 753 cm−1, which is significantly lower than that of silicate, gallate and germanate glass and the smaller matrix phonon energy can be conductive to the increase 2.0 μm-band emission intensity. The continuous laser with the maximum laser output power of 0.993 W and 2051 nm -wavelength of 31.9%-slope efficiency is output within the 0.5 m glass fiber and the experiment adopts 1560 nm erbium-doped fiber laser(EDFL) as the pump source and the self-built all-fiber laser. Therefore, the glass fiber has excellent laser characteristics and it is suitable for the 2.0 μm-band laser. [ABSTRACT FROM AUTHOR]

High concentration Dy3+ doped 75TeO 2 -25YF 3 -xDyF 3 (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 DyF 3 concentrations. The maximum phonon energy of the glass is about 770 cm-1. Ω 6 and χ are 3.5 and 0.51 when DyF 3 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 DyF 3 , which may be due to the depolymerization of [TeO 4 ], gradually converting into [TeO 3+1 ] and [TeO 3 ], 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 4F 9/2 → 6H 13/2. 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. [ABSTRACT FROM AUTHOR]

In this study, Tm3+-doped gallium tellurite glass samples were fabricated in order to achieve the fluorescence emission at 1.8 μm. Firstly, the optical properties (such as dispersion, absorption and fluorescence curves) of the glass samples were investigated and discussed. Meanwhile, the nonlinear refractive index, Judd-Ofelt (J-O) parameters, effective fluorescence bandwidth, absorption and emission cross sections, as well as gain coefficient of the glass samples were estimated in detail utilizing the collected data. Subsequently, lifetime evaluation was undertaken to explore the fluorescence decay behavior of Tm3+ at the 3F 4 energy level. The approach to in-depth analysis of the energy transfer process between Tm3+ was carried out by the quantitative calculations. Notably, we found that the quantum efficiency of the GT-0.75 sample was as high as 73.5% under the action of the 808 nm laser diode. Lastly, the thermal characteristics and internal structural units of the glass samples were depicted by the DSC curves, Raman and FTIR spectra. The present results indicate that Tm3+ -doped gallium tellurite glass is a kind of laser glass material with great potential in 1.8 μm wavelength band. [ABSTRACT FROM AUTHOR]

In this study, we prepared Tb3+-doped bismuth tellurite glasses by a high-temperature melting method. The matrix glass was characterized by higher thermal stability (ΔT = 102 °C) and lower maximum phonon energy (614 cm−1). Based on absorption spectra, Judd-Ofelt analysis revealed the spontaneous radiation transition probability (269.34 s−1) and fluorescence branching ratio (41.55%) of 5D 4 →7F 5 transition. The luminescence peaks of the samples were located at 486 nm and 545 nm blue-green bands. Meanwhile, the luminescence intensity increased with the increase of Tb3+ concentration and reached the maximum at 4mol% Tb 4 O 7. In addition, emission cross-section and gain coefficients were calculated in blue wavelength range, the maximum values were 2.01 × 10−22 cm−1 and 2.92 cm−1, respectively. Combining all the above results, Tb3+ doped bismuth tellurite glass had potential application value in the field of blue-green communication. [ABSTRACT FROM AUTHOR]

Tm3+/Yb3+ co-doped TeO 2 –Bi 2 O 3 –ZnO glass has been synthesized by using the melt-quenching method in this paper. According to Gaussian fitting and J-O theory, the impact of phonon energy on both structure and fluorescence properties has been investigated by introducing different phonon energy oxides. It was shown that various glass network units were observed in Raman spectra. Moreover, the Te–O–Te can be destroyed via the addition of WO 3 and B 2 O 3 , resulting in [TeO 4 ] transformed to [TeO 3 ] and [TeO 3+δ ] groups, while thermal stability and fluorescence properties were enhanced. And the phonon energy (ħω 0) increased from 758 to 926 (WO 3) and 1097 cm−1 (B 2 O 3). Meanwhile, the intensities of the absorption and fluorescence spectra were improved significantly by the change of glass network units. The effective fluorescent bandwidth (Δλ eff) was raised from 223 to 227 and 231 nm, and the gain coefficient was from 1.60 cm−1 to 1.71 cm−1 and 1.72 cm−1. Finally, the micro-parameters for energy transfer processes have been calculated by using a spectral overlap method. Results indicate that the energy transfer process between Tm3+ and Yb3+ was more efficient with the high phonon energy oxide introduction (WO 3 and B 2 O 3), which provides practical significance that will be beneficial for obtaining the 2 μm high gain material. • Tm3+/Yb3+ co-doped 85 TeO 2 –5Bi 2 O 3 –10ZnO glass has been prepared with partial substitution of TeO 2 by WO 3 or B 2 O 3. • The impact on the structure of bismuth-tellurite glasses has been investigated when introducing WO 3 and B 2 O 3. • The influence on spectroscopic properties of Tm3+/Yb3+ co-dopedtellurite glasses has been characterized by WO 3 and B 2 O 3. • The energy transfer process has been analyzed between Tm3+ and Yb3+ based on different phonon energy at the 2 μm. [ABSTRACT FROM AUTHOR]

1 The modified topological cage can enhance the structure and emission properties. 2 Bismuth-tellurite glasses have good thermal stability (ΔT=143°C) for fiber drawing. 3 Lower maximum phonon energy makes the energy transfer of Tm3+/Yb3+ more efficient. 4 TBBB3 has a large emission cross-section (9.79 × 10−21 cm2, 1857nm). Tm3+/Yb3+ co-doped TeO 2 -Bi 2 O 3 -B 2 O 3 -BaF 2 glasses were synthesized by the melt-quenching method. The Raman and FT-IR spectra were deconvoluted by the Gaussian decomposition method to determine the molecule vibration glass network. And the luminescence properties at 2 μm were systematically analyzed under 980 nm laser diodes (LD) pumped according to J-O theory. Furthermore, the spectroscopic parameters, absorption, emission cross-sections, and gain coefficient of Tm3+ in TBBB3 were calculated by absorbance and fluorescence spectra. Eventually, the energy transfer process was quantitatively characterized by using a spectral overlap method. The maximum emission cross-section of Tm3+ is 9.79 × 10−21 cm2 (at 1857 nm) when the doped concentration ratio of Tm3+/Yb3+ is 0.5: 2 (mol%). Meanwhile, the backward energy transfer coefficient (C A-D) is much smaller than the forward (C D-A), and the energy transfer rate W ET is 1691.5 × 10−20 cm3/s. All these results indicate that the glass presented is an ideal laser gain material at 2 μm. [ABSTRACT FROM AUTHOR]

Through the traditional molten method, we designed and fabricated Nd3+/Yb3+ co-doped bismuth borate glasses, and completed the study of the luminescence mechanism of rare earth ions in 1 μm band as well as the doping concentration on the luminescence performance of the glass. Firstly, the thermodynamic properties of the glass sample was evaluated by utilizing DSC curve. Subsequently, the spectral properties of BBFNY-2 glass sample was revealed by analyzing the absorption spectra, fluorescence spectra, fluorescence lifetimes and Judd-Ofelt (J-O) theory. Finally, the energy transfer mechanism between rare earth ions Nd3+→Yb3+ was analyzed in detail. The increase of fluorescence intensity at 1008 nm in the glass was calculated corresponding to the broadening of Δ λ eff from 103 nm to 107 nm, and the obtainable OCT (optical coherence tomography) axial resolution increased from 4.4 μm to 4.1 μm. In this work, the small absorption cross section of Yb3+ at 980 nm in 55Bi 2 O 3 –35B 2 O 3 –10BaF 2 (mol%) glass is effectively solved by Nd3+→Yb3+ energy transfer. Meanwhile, the relevant parameters of the prepared BBFNY-2 glass sample were calculated, and the results suggested that the fabricated glass samples have large microscopic parameters, high transfer efficiency and long fluorescence lifetime. In the results, it was revealed that the via non-radiative electric dipole-dipole process was responsible for the energy transfer and was proportional to the concentration of the Nd3+ donor ions. With all the results, the prepared BBFNY-2 glass sample is a high-potential candidate material for ∼1 μm laser applications. • Bismuth borate glass singly-doped and co-doped Nd3+ and Yb3+ were prepared. • The Bi 2 O 3 –B 2 O 3 –BaF 2 glasses are activated with Nd3+ and Yb3+. • Energy transfer from Nd3+ to Yb3+ takes places. • An analysis based on the Dexter theory is done. • The small σ abs of Yb3+ at 980 nm in BBF glass was solved by the energy transfer of Nd3+.→Yb3+. [ABSTRACT FROM AUTHOR]

• High concentration of Tm3+ ion doped fluorotellurate glass was prepared. • The TeO 2 -Al 2 O 3 -BaF 2 glasses are activated with Tm3+. • A large emission cross section (9.50 × 10−21 cm−2) in the ~ 2 µm band was achieved by modulating the Tm3+ doping concentration. • By analyzing the energy transfer mechanism, the energy transfer rate W ET between Tm3+ was calculated as 2073.4 × 10−20 cm3/s. The high concentration Tm3+ ions doped fluorotellurate glass samples (TeO 2 -Al 2 O 3 -BaF 2) fabricated by high-temperature fusion technique and the luminescence properties of the glass samples were examined based on absorption and fluorescence spectra to forecast the latent capability of TAFT4 glass for ~ 2 µm band fiber lasers. The thermodynamic properties of the glass samples utilized for drawing the optical fiber, internal structure and the maximum phonon energy were characterized based on the thermal stability parameter ΔT and Raman spectra, respectively. The Judd-Ofelt (J-O) intensity parameters (Ω t) was estimated from the recorded absorption spectral data, and the estimation results showed that the value of Ω 2 was as high as 6.97 × 10−20 cm2. To reveal the spectral properties of TAFT4 glass sample, significant radiative parameters including spontaneous raditive transition probabilities (A rad), fluorescence branching ratios (β), radiative lifetimes (τ rad), absorption and emission cross sections of Tm3+ ions excitation energy levels were determined using J-O intensity parameters. Furthermore, the calculation of the gain coefficient is included to determine its capability as a gain medium. The fluorescence decay behavior of Tm3+ ions and the energy transfer mechanism were investigated and analyzed in detail, and the macroscopic rate W ET of the CR process between Tm3+ ions in TAFT4 glass was quantified by the transfer constants C D-D and C D-A. The value of W ET was high up to 2073.4 × 10−20 cm3/s by estimation. As mentioned above, the fabricated TAFT4 glass sample may be a suitable gain medium that can be used for ~2 µm band fiber lasers. [ABSTRACT FROM AUTHOR]

In this work, Er3+/Yb3+ co-doped 40Bi 2 O 3 -30GeO 2 -15Ga 2 O 3 -15Na 2 O glass was papered by melt-quenching method. The thermal properties and spectroscopic were studied. The glass has good thermal stability and the maximum phonon energy is 750 cm−1, which is benefited for 1.53 μm emission. According to the J-O theory and absorption spectra, the J-O intensity parameters were calculated, the spectral quality factor χ = Ω 4 /Ω 6 of BGGN4 glass is 2.236. Under 980 nm excitation, the 1.53 μm luminescence characteristics of these glasses were studied. When the Er3+/Yb3+ ions doping concentration ratio (mol%) reaches 0.5:1.0, the maximum fluorescence intensity can be obtained, and the maximum emission cross section is 6.4 × 10−21cm2. The maximum stimulated gain coefficient in the 1.53 μm band is 4.6 cm−1. Finally, the up-conversion emission and energy transition mechanism of Er3+/Yb3+ co-doped BGGN glass were studied. The results indicate the prepared Er3+/Yb3+ co-doped bismuth germanate glass have good gain performance and is an ideal 1.53 μm laser gain material. • Er3+/Yb3+ co-doped 40Bi 2 O 3 -30GeO 2 -15Ga 2 O 3 -15Na 2 O glass was prepared by melt-quenching method. • The prepared glass has relatively low maximum phonon energy (750 cm−1). • Large σ emi indicate good gain properties of prepared glass. • Up-conversion and energy transfer mechanism are analyzed. [ABSTRACT FROM AUTHOR]

• Tm3+-doped Bi 2 O 3 -GeO 2 -Ga 2 O 3 Na 2 O glass was prepared by melt-quenching method. • Effects of Ga 2 O 3 on thermal stability and emission properties were studied. • The prepared glass has relatively low maximum phonon energy (745 cm−1). • Large σ emi ×τ m and σ emi × ∆λ eff indicate good gain properties of prepared glass. • Energy transfer coefficient of cross relaxation process is calculated. In this paper, Tm3+-doped Bi 2 O 3 -GeO 2 -Ga 2 O 3 Na 2 O glass was synthesized using melt-quenching method. Spectroscopic and thermal properties of the presented glass was characterized. The effects of Ga 2 O 3 oxide on the glass structure and ~1.8 µm emission properties were investigated. The thermal stability and Raman spectroscopic analysis showed that partial substitution of GeO 2 by Ga 2 O 3 resulted in decreasing of glass transition temperature and maximum phonon energy (745 cm−1). It is known that relatively low maximum phonon energy is good for ~1.8 µm emission. Based on the measured absorption spectra, Judd-Ofelt intensity parameters and other spectroscopic parameters were calculated to elucidate the radiative properties of the presented Tm3+-doped glass. Moreover, under the excitation of 808 nm laser diode, broadband ~1.8 µm fluorescence was observed. For Bi 2 O 3 -GeO 2 -Ga 2 O 3 Na 2 O glass doped with 1.0 mol% Tm 2 O 3 , the large values of σ emi × τ mea product (8.30 × 10−21 cm2ms) and σ emi × ∆λ eff product (16.00 × 10−26 cm3) indicate a good gain property as well as a good gain bandwidth. Finally, the energy transfer coefficient (C D- A = 12.0 × 10−40 cm6/s) of cross relaxation (3H 4 , 3H 6 → 3F 4 , 3F 4) between Tm3+ ions is calculated. These results indicate that the prepared Tm3+-doped Bi 2 O 3 -GeO 2 -Ga 2 O 3 Na 2 O glass is a promising gain material for ~1.8 µm band solid-state laser applications. [ABSTRACT FROM AUTHOR]

Er3+/Yb3+ co-doped large-mode-area double-cladding fibers based on Bi 2 O 3 -GeO 2 -Ga 2 O 3 –Na 2 O–CeO 2 glass material were fabricated using a rod-in-tube method. Due to the low core numerical aperture (NA = 0.057), the prepared fiber can operate in single-mode regime with a cut-off wavelength of ∼1.49 μm while its core diameter reaches 20 μm. Based on the measured absorption spectrum, the spectroscopic parameters of Er3+/Yb3+ co-doped core glass were calculated by Judd-Ofelt theory. Relatively large spectroscopic quality factor (χ = 3.139), spontaneous transition probability (266.58 s−1) and radiative lifetime (3.75 ms) indicate the core glass has good radiation characteristics. Moreover, under 980 nm excitation, the strongest 1.53 μm emission is achieved in core glass while the doping concentration ratio of Er3+/Yb3+ is 1.0 mol%: 2.5 mol%. And the maximum emission cross section is calculated to be 8.2 × 10−21 cm2 at 1532 nm by McCumber theory. Finally, a stable laser output at 1535.4 nm is achieved in a 50 cm long as-drawn Er3+/Yb3+ co-doped fiber, yielding a maximum laser output power of 93.64 mW and a slope efficiency of 11.75%. The excellent optical properties indicate the prepared Er3+/Yb3+ co-doped fibers have potential applications for 1.53 μm band high power fiber laser. • Large-mode-area double-cladding bismuthate glass fibers are fabricated. • Optical properties of the present bismuthate glasses are improved by CeO 2. • Core and cladding glasses have excellent thermal properties and compatibilities. • Large τ mea (4.12 ms) and σ emi (8.2 × 10−21 cm2) have been realized in core glass. • A stable laser output is achieved in the present Er3+/Yb3+ co-doped optical fiber. [ABSTRACT FROM AUTHOR]

• Tm3+ doped TeO 2 –B 2 O 3 –Al 2 O 3 –Na 2 O glass was prepared by melt-quenching method. • The structure of boro-tellurite glass containing Al 2 O 3 was analyzed by FTIR and Raman spectra. • The prepared glass has large Ω 2 (6.53 × 10−20 cm2) and high spontaneous probability a rad (499.58s−1). • Large σ emi × Δλ eff (21.25 × 10−26 cm3) indicated the prepared glass has good gain properties. • The energy migration and cross-relaxation processes are analyzed. This study aims to investigate the characteristics of Tm3+ doped TeO 2 –B 2 O 3 –Al 2 O 3 Na 2 O glass. The structures that exist in host glass were obtained from the Raman spectrum. Due to the introduction of sodium and aluminum, the Te O Te bond is broken, and the amount of bridge oxygen is reduced, causing the transformation of [TeO 4 ] structural units to [TeO 3+1 ] and [TeO 3 ] structural units. The spectrum characteristics of Tm3+ in the samples were predicted by theoretical calculations. Prepared Tm3+ doped glass has large Ω 2 and small Ω 6 , which is connected to the ligand field's asymmetry and the stiffness of the network. Furthermore, under the excitation of 808 nm laser diode, broadband ∼1.8 μm fluorescence was observed and the effective fluorescent bandwidth Δλ eff of 1830 nm emission in the glass is about 234 nm. For the sample with 0.5 mol% Tm 2 O 3 , the large values of emission cross-section product (9.08 × 10−21 cm2) and σ emi × Δλ eff product (21.25 × 10−26 cm3) indicate a good gain property as well as a good gain bandwidth. Eventually, the energy migration process and cross-relaxation process between thulium ions were analyzed. The micro-parameter of the CR process is 4.049 × 10−40 cm6/s. Hence, the results indicate that the prepared Tm3+ doped glass could be a potential candidate for ∼2 μm mid-infrared laser devices. [ABSTRACT FROM AUTHOR]

Tm3+ doped Bi 2 O 3 -GeO 2 -Na 2 O glass samples were synthesized by conventional melt-quenching method. The Raman spectra measurements showed the maximum phonon energy of prepared glass is 794 cm−1, which is considerably lower than silicate glasses. Based on the measured absorption spectra, Judd-Ofelt intensity parameters, spontaneous radiative transition probabilities and radiative lifetimes were calculated to elucidate the radiative properties of Tm3+ in the presented glass. Intense near infrared emission around ~2 μm was obtained under the pump of 808 nm laser diode. A large stimulated emission cross section (5.51 × 10−21 cm2 at 1851 nm) of Tm3+: 3F 4 → 3H 6 was achieved in the prepared bismuth germanate glass doped with 1 mol% Tm 2 O 3. Besides, the energy transfer processes among Tm3+ were analyzed using the extended overlap integral method. These results indicate that the presented glass is a promising candidate for ~2 μm laser applications. •Tm3+-doped Bi 2 O 3 -GeO 2 -Na 2 O glasses were prepared and investigated. •The host glass has relatively low maximum phonon energy (794 cm −1). •High A rad (351.43 s−1) and σ emi of ~2 μm (5.51 × 10 −21 cm2) have been realized. •The large σ emi × τ m (5.45 × 10 −21 cm2ms) indicates a high gain around ~2 μm. • The energy transfer rate W ET is 768 × 10 −20 cm3/s in BGT4 glass. [ABSTRACT FROM AUTHOR]

The Nd 3+ /Yb 3+ co-doped borosilicate glasses are fabricated by using a conventional melt quenching technique in air atmosphere. The Spectroscopic properties of 1.0 μm emission in Nd 3+ /Yb 3+ co-doped borosilicate glasses are investigated under 808 nm excitation. The luminescence decay curves show a nonexponential character, the energy transfer microscopic parameters and transfer efficiencies are calculated. Results indicate that the energy transfer takes place via nonradiative electric dipole–dipole processes and is enhanced with the concentration of Nd 3+ donor ions. The glass co-doped with 0.5 mol% Nd 2 O 3 and 2 mol% Yb 2 O 3 has a large microscopic parameters 100×10 −40 cm 6 s −1 , high transfer efficiencies 73.58% and long fluorescence lifetime 0.3 ms at 1020 nm, which is of great potential as a candidate material in the development of multiple-pump-channel Yb 3+ fiber lasers. [ABSTRACT FROM AUTHOR]