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Issue 2 ， 2022
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Three-step Epitaxial Growth of GaAs on Si by MOCVD echnology Enhanced Publication
Abstract：Epitaxial growth of high-quality gallium arsenide(GaAs) films on silicon(Si) is the key factor to realize the monolithic integration of silicon-based light sources. However, the large lattice mismatch and thermal mismatch between Si and GaAs have a serious impact on the quality of GaAs films obtained by epitaxial growth. The growth of GaAs on Si was studied by metal-organic chemical vapor deposition(MOCVD). In this paper, the three-step growth method was used to further reduce the surface roughness and threading dislocation density of GaAs on Si by combining low temperature GaAs nucleation layer, high temperature GaAs layer and thermal cycle annealing. And the changes of residual stress in samples grown by different methods were tracked by X-ray diffraction(XRD) ω-2θ scan. Finally, when the growth time of GaAs low-temperature nucleation layer was 62 min (the growth thickness was about 25 nm), the full width at half maximum(FWHM) of GaAs epitaxial material exhibiting tensile stress with GaAs(004) rocking curve measured by XRD was 401″, threading dislocation density was 6.8×107 cm-2 and surface roughness over 5 μm×5 μm scan areas of 6.71 nm was obtained by means of three-step growth and cyclic annealing.Keywords：metal-organic chemical vapor deposition;GaAs;Si;Heteroepitaxy- 888
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Published：2022-02-25
Cover Story
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Research Advances of Continuous-wave Laser Driven Full-spectrum White Light Based on Inorganic Material System Enhanced Publication
Abstract：Full-spectrum white light, covering visible to infrared, is of great significance to optical research due to its solar-like spectrum. The full-spectrum white light generated by a continuous-wave laser irradiation on different materials has attracted extensive research interest because of its special optical properties and high luminous efficiency. In this review, the inorganic materials emitting full spectrum white light are classified and summarized from the point of activation center. Then, the photophysical process of full spectrum white light in inorganic material system is summarized and analyzed from three aspects: spectral property, temperature property, and photoelectric property, and its application is promising. Finally, the future research direction and development trend of this nonlinear optical phenomenon are summarized.Keywords：full-spectrum white light;inorganic material;nonlinear optical process- 491
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Published：2022-02-25
Invited Review
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Elaboration and Mid-infrared Emission of KYb3F10∶Er3+ Nanocrystals Embedded in Glass Ceramics Enhanced Publication
Abstract：Mid-infrared lasers operating at around 3 μm have been paid much attention due to their significant potential at civil and military field. Traditional mid-infrared laser glass matrix presents high phonon energy, which causes the radiative transition probability of luminescent ions being greatly weakened, and thus leads to the inability to obtain effective laser output. Therefore, it is of great value to explore efficient and stable gain materials for 3 μm laser. In this paper, we report the in-situ precipitation of KYb3F10∶Er3+ nanocrystals from SiO2-ZnF2-KF-YbF3-ErF3 fluorosilicate glass matrix. The obtained glass ceramic can maintain more than 80% transmittance. The nanocrystal species and elemental distribution in the glass were characterized by X-ray diffractometry(XRD) and transmission electron microscopy(TEM) technology. Under 980 nm laser diode(LD) excitation, the mid-infrared emission at 2.7 μm of Er3+for the heat-treated sample is greatly enhanced, which is about 19 times stronger than that of the precursor sample. The related mechanism for the luminescence enhancement is further explained by the results of absorption spectra and steady state fluorescence spectra. The present results may provide reference data and research ideas for the development of ~3 μm laser gain materials.Keywords：glass ceramics;fluoride nanocrystals;Er3+ ions;mid-infrared emission- 271
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Published：2022-02-25 -
Down-conversion Luminescence Performance of Dy3+ Doped Lu2O3 and Y2O3 Single Crystal Fibers for Temperature Sensing Enhanced Publication
Abstract：Rare earth sesquioxide single crystal fibers(SCFs) are considered to be potential high-temperature sensing media due to their ultra-high melting point(~2 400 ℃), stable physical and chemical properties and flexible structure. The transparent and crack-free Dy3+ doped Lu2O3 and Y2O3 single crystal fibers(SCFs) were successfully grown by laser heated pedestal growth(LHPG) method. According to the 4I15/2 and 4F9/2 energy levels of Dy3+ ion as a pair of thermally coupled energy levels(TCLs), the down-conversion luminescence in the wavelength range of 430-520 nm was obtained. The fluorescence intensity ratio(FIR) measurement technique shows that the Dy3+ doped Lu2O3 and Y2O3 crystals have a good temperature dependence in the temperature range of 298-673 K. The maximum relative sensitivity and absolute sensitivity of Dy∶Lu2O3 in this range are 0.97%·K-1(315 K) and 1.62×10-4 K-1(673 K), respectively, showing more excellent temperature sensing performance.Keywords：laser heated pedestal growth(LHPG) method;sesquioxide single crystal fibers(SCFs);down-conversion luminescence;fluorescence intensity ratio(FIR);temperature sensing- 485
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Published：2022-02-25 -
Upconversion Luminescence and Temperature Sensing Characteristics of Lu2O3∶Er3+/Yb3+ Phosphor Enhanced Publication
Abstract：Lu2O3∶0.5%Er3+/x%Yb3+(x=1, 3, 5) phosphors were prepared by CO2 laser zone melting method. X-ray diffraction results showed that all the prepared Lu2O3∶Er3+/Yb3+ phosphors have a pure Lu2O3 crystal phase. Under the excitation of a 980 nm laser diode, the samples emit bright up-conversion luminescence(UCL). The luminescence intensity and the ratio of green band to red band in luminescence spectra change with Yb3+ concentration. Besides, the UCL intensity reaches its maximum value when the doping concentrations of Er3+ and Yb3+ ions are 0.5% and 3%, respectively. The temperature sensing characteristics of Lu2O3∶0.5%Er3+/3%Yb3+ were investigated using fluorescence intensity ratio(FIR) technique from 298 K to 873 K. The maximum absolute sensitivity is 0.006 0 K-1 at 532.8 K, and the maximum relative sensitivity is 0.009 0 K-1 at 298 K. The above results indicate that the Lu2O3∶Er3+/Yb3+ phosphor is very suitable for wide-range temperature sensing.Keywords：Lu2O3∶Er3+/Yb3+;upconversion luminescence;fluorescence intensity ratio(FIR);fluorescence temperature sensing- 224
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Preparation, Optical and Scintillation Properties of Organotin Compounds Doped Polyvinyltoluene-based Plastic Scintillators Enhanced Publication
Abstract：Traditional plastic scintillators are not suitable for energy spectroscopy detection due to their low effective atomic number and low density. The preparation of plastic scintillators doped with organic heavy metal compounds provides an effective avenue for energy spectroscopy detection for plastic scintillators. Organotin compounds doped plastic scintillators possess high photopeak sensitivity and retain fast decay characteristics of plastic scintillators. In this paper, polyvinyltoluene(PVT)-based plastic scintillators doped with different concentrations of 2-(tributylstannyl)furan were successfully prepared by free-radical polymerization, and their optical and scintillation properties were characterized and compared. The optical transmittance of 20% 2-(tributylstannyl)furan doped plastic scintillator based on PVT can be up to 90%. Under X-ray excitation, the radioluminescence spectrum of sample shows a broad band between 390 nm and 550 nm peaking at 425 nm. The sample demonstrates a light yield of 6 700 ph/MeV and an energy resolution of 15.8%@662 keV. The scintillation decay time is about 4.3 ns. 1 inch diameter plastic scintillator loaded with 20% 2-(tributylstannyl)furan was also prepared with a light yield of 6 300 ph/MeV and an energy resolution of 15.8%@662 keV.Keywords：plastic scintillators;organotin compounds;optical properties;energy resolution- 487
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Preparation and Polychromatic Upconversion Luminescence of Hexagonal NaErF4 and NaErF4@NaYF4 Core-shell Particles Enhanced Publication
Abstract：Hexagonal NaErF4 and NaErF4@NaYF4 core-shell upconversion luminescent materials were synthesized by simple hydrothermal method. The morphology, structure and upconversion luminescence properties of the obtained materials were studied by scanning electron microscopy(SEM), X-ray powder diffraction(XRD) and fluorescence spectroscopy(PL). The results show that the pure NaErF4 sample has hexagonal column morphology with smooth surface, and the side length and thickness are both 1 μm. With the coating of NaYF4 shell, a large number of cubic NaYF4 nanoparticles appeared around hexagonal NaYF4 particles, and the NaErF4@NaYF4 core-shell materials were obtained. The luminescence spectra show that the upconversion luminescence intensity can be effectively enhanced by coating NaYF4 shell on the surface of hexagonal NaErF4. The three emission peaks at 527, 543, 663 nm correspond to 2H11/2→4I15/2, 4S3/2→4I15/2 and 4F9/2→4I15/2 energy level transitions of Er3+, respectively. Meanwhile, with the increase of the molar ratio of Y∶F in the shell of NaErF4@NaYF4 sample, the crystal diffraction peak of cubic NaYF4 increases gradually, moreover, the red green ratio(R/G) gradually increases in the emission spectrum of the sample, and the luminescence color gradually transits from green to yellow, realizing multi-color luminescence.Keywords：upconversion luminescence;NaErF4@NaYF4;red green ratio- 229
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Published：2022-02-25 -
Local Electronic Structure of Lithium Nitrogen Codoped ZnO Films Revealed by X-ray Absorption Fine Structure Spectroscopy Enhanced Publication
Abstract：It is to reveal the formation mechanism of Li and N codoped p-ZnO films and the cause for the stable p-type conductivity. The films has been studied by investigating their local electronic structures using X-ray photoelectron spectroscopy and X-ray absorption fine structure spectroscopy based on synchrotron radiation source. The signals of Li—N bond and Li—N complex acceptors in the p-ZnO films have been collected, and the acceptor level estimated from photoluminescence spectroscopy is about 122 meV. The formation of Li—N complex acceptors has been confirmed, and the realization of Li—N bond has been attributed to the origin of the good stability of the p-type ZnO films obtained by Li, N codoping method.Keywords：Zinc oxide;P-type doping;Formation mechanism;Stability;X-ray absorption fine structure spectroscopy- 148
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ZnO Luminescence Behavior Under Low Temperature by Ion-beam-induced Luminescence Enhanced Publication
Abstract：Ions beam induced luminescence(IBIL) can be used to analyze the evolution of defects under different temperatures and different ion irradiation conditions in real-time in situ. In this paper, the evolution of luminescence of point defects with fluence inside ZnO single crystals at 300,200, 100 K was analyzed using 2 MeV H+. The deep-band emission and near-band emission of ZnO were observed in the experiments, and combined with the Voigt splitting results, it was determined that the origin of red emission(1.75 eV) was VZn, and the orange-red emission(1.95 eV) was associated with the transitions from the conduction band to Oi. While for the green emission(2.10 eV) that redshifts with decreasing temperature, it was mainly related to VO. The reason of redshift was that more electrons from conduction band were released to Zni. For the near-band emission, 3.10 eV and 3.20 eV emission mainly associated with the transitions from Zni to the valence band and recombination of excitons, and the redshifts were mainly due to the localization energy level of Zni and the temperature-induced band-gap shrinkage. Using the single exponential formula to fit the decay of the luminescence intensity with fluence, the decay rate costant(f) was used to characterize the irradiation hardness of the defects. It was found that all three peaks of the deep-band emission were the maximum irradiation hardness at 200 K, while for the two peaks of the near-band emission, they had the maximum irradiation hardness at 300 K. This may be due to the fact that during the temperature increase, a large number of electron holes obtained enough thermal kinetic energy to be released from the originally bound by the point defect, coupled with the temperature-induced band-gap shrinkage, the dual effect made the radiation recombination inside the crystal enhanced, and thus the irradiation resistance was enhanced.Keywords：ion-beam-induced luminescence;temperature;point defects;ZnO- 130
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Published：2022-02-25
Synthesis and Properties of Materials
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Zinc Chloride Modification of Blue Quantum Dot Light-emitting Diode Enhanced Publication
Abstract：Inorganic zinc chloride(ZnCl2) was used as a ligand to modify cadmium-based blue quantum dot(B-QD) film. In this case, ZnCl2 can partially replace the original long-chain ligand of oleic acid(OA) because of a strong interaction between ZnCl2 and QDs. The replaced ZnCl2 can passivate the surface defects of QDs to enhance the photoluminescence quantum yield(PLQY) of the QDs film. Meanwhile, the strategy can significantly improve carrier transport capacity and pull up the vacuum energy level of the QDs film by 0.2 eV due to ZnCl2 dipoles, which may improve electron and hole injection balance, reduce the turn-on voltage of EL devices, and extend device lifetime as well. This method might provide an effective way to improve performances of blue quantum dot light-emitting diodes.Keywords：zinc chloride modification;inorganic ligand exchange;blue quantum dot light-emitting diodes;balanced carriers;efficiency roll-off improvement- 204
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Single-longitudinal Mode Thulium-doped Fiber Laser in 2 050 nm Band Based on Passive Compound Triple-ring Cavity Enhanced Publication
Abstract：A single-longitudinal-mode(SLM) thulium-doped fiber laser in 2 050 nm band enabled by a novel passive triple-ring compound cavity filter was proposed and demonstrated. Theoretically analyzing of this sub-cavity filter was performed in detail. The use of the compound cavity filter in the fiber laser guaranteed the SLM lasing by carefully adjusting the effective free spectral range and transmission bandwidth for ultra-narrow filtering. The output wavelength of the fiber laser was 2 048.48 nm, and the optical signal-to-noise ratio was 70 dB. The wavelength and power fluctuations measured within 100 min were less than 0.02 nm and 0.453 dB, respectively. Experimental results verified that the fiber laser could operate in a stable SLM lasing state. The proposed laser is promising to be used in free-space optical communication or be used as the seed source of the high power fiber laser for Doppler Lidar.Keywords：fiber laser;thulium-doped fiber;single-longitudinal-mode;fiber Bragg grating- 137
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Research Progress on Optimizing Performance of Cu2ZnSn(S,Se)4Thin-film Solar Cells by Partial Cation Substitutions Enhanced Publication
Abstract：As a representative of inorganic thin film solar cells, Cu2ZnSn(S,Se)4(CZTSSe) thin film solar cells have attracted much extensive attention, since the constituent elements are rich in earth, low toxic, etc. At present, high defect density of the absorber layer and low open circuit voltage of device are both considered as two key factors limiting the efficiency of device. In order to break though the two difficulties, the researchers developed the substitutions of Cu+/Zn2+/Sn4+ by another cation. This can optimize the film properties of the harmful defects, crystal structure, and band structure, improving the performance of devices. Here, we classify by equivalent and inequivalent cation substitutions to elaborate current research development of CZTSSe thin film solar cells by cation substitution, and summarize their advantage and disadvantage in optimizing performance of devices.Keywords：thin film solar cell;Cu2ZnSn(S,Se)4;cation substitutions- 150
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Published：2022-02-25
Device Fabrication and Physics
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Simulation of 1 550 nm Femtosecond Pulse Self-similar Fiber Amplification Enhanced Publication
Abstract：In this paper, an all-fiber structure of ultrashort pulse erbium-doped fiber amplifier was simulated, and the self-similar pulse amplification processed of erbium-doped fiber under normal dispersion conditions was analyzed in detail. In the fiber pre-amplifier, a high positive dispersion erbium-doped fiber was be used to pre-shape the pulse shape. The soliton mode-locked pulse with the repetition frequency of 43 MHz, pulse width of 600 fs, and average output power of 1.2 mW was pre-shaped into a parabolic pulse. The pre-shaped pulse is amplified by the optical fiber main amplifier. After two-stage optical fiber amplification, the signal optical power of 1.2 mW was amplified to 102 mW, and the amplification gain was 19.3 dB. The influence of erbium-doped fiber length and amplification power on the evolution of pulse self-similarity was analyzed in this article. The amplified pulse was compressed to 53 fs through 4.4 m long single-mode fiber and the peak power was 44.8 kW.Keywords：fiber amplifier;self-similarity;normal dispersion erbium-doped fiber;ultrashort pulse;simulation- 178
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Numerical Simulation on Output Characteristics of 980 nm Tapered Semiconductor Lasers Enhanced Publication
Abstract：Tapered semiconductor lasers with high power and high brightness characteristics have been extensively used in many fields such as laser processing, free space communications, and medical etc. A simulation on 980 nm tapered semiconductor lasers has been done based on the wide-angle differential beam propagation method(WA-FD-BPM) in this work. The effects of structural parameters(such as ridge etching depth, taper angle, different ridge/taper length ratio, taper etching depth, front cavity reflectance) on the beam quality and P-I-V characteristics of the device are analyzed in detail. The analysis shows that the geometric loss of the tapered waveguide is the main factor leading to the decrease of the slope efficiency of the device, and the optical pumping effect is an important factor affecting the deterioration of the beam quality. The beam quality can be improved by reducing the reflectivity of the front cavity surface of the device. The results in this paper can provide a certain theoretical reference for the design and analysis of tapered lasers.Keywords：Tapered semiconductor laser;wide-angle differential beam propagation;beam quality;optical field distribution- 218
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Published：2022-02-25
Theoretical Calculation and Spectral Analysis
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Preparation of Copper/Silver Bimetallic Nanoclusters Stabilized by Penicillamine and Their Application in Silver Ion Detection Enhanced Publication
Abstract：Bimetallic copper-silver nanoclusters(DPA-Cu/Ag NCs) were prepared by one-pot method using penicillamine as reducing agent and stabilizer, and used as a sensor to detect silver ions in water samples. The Ag+ sensor has the advantages of low price, quick analysis speed and high selectivity. The structure and chemical composition of bimetallic copper-silver nanoclusters were characterized by transmission electron microscopy(TEM). The results showed that the DPA-Cu/Ag NCs exhibited a maximum emission at 555 nm with an excitation wavelength of 300 nm. It is a milky white solution under visible light, and the solution shows bright yellow fluorescence under UV light. When the preparation conditions of DPA-Cu/Ag NCs are optimized, it can be used as a probe to detect silver ions with high selectivity and sensitivity. The detection limit of silver ion is 0.3 μmol/L and the linear range is 0-500 μmol/L. The DPA-Cu/Ag NCs probe can also be applied to the detection of silver ion concentration in natural environmental water samples(lake water, bottled mineral water and laboratory tap water, etc.), and its detection performance is excellent with good percent of accuracy and reproducibility, indicating that the DPA-Cu/Ag NCs probe has extremely high application value in environmental monitoring.Keywords：metal nanocluster;fluorescence;bi-metal;silver ion detection- 193
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Published：2022-02-25
Luminescence Applications and Interdisciplinary Fields
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