Based on the first-order correlation function of light,we propose analogous optical coherent states(AOCSs)sourced by partially coherent beams,which can nondiffractively propagate with sinusoidal oscillation in the har...Based on the first-order correlation function of light,we propose analogous optical coherent states(AOCSs)sourced by partially coherent beams,which can nondiffractively propagate with sinusoidal oscillation in the harmonic potential when the nondiffraction propagation matching condition(NPMC)is met.Unlike the traditional quantum coherent state,the minimum uncertainty of AOCS is related to the coherence of light,and only when the NPMC is met,its uncertainty is the least.Furthermore,based on the mathematical similarity between the Schrödinger and the Helmholtz equations,we find that our proposed AOCSs correspond to the partially coherent steady states of the harmonic oscillator.Our research not only increases the understanding of the coherence of light and enriches the types of nondiffraction beams but also increases the understanding of the quantum coherence regulating the evolution of probability waves.展开更多
Tissue clearing combined with high-resolution confocal imaging is a cutting-edge approach for dissecting the three-dimensional(3D)architecture of tissues and deciphering cellular spatial interactions under physiologic...Tissue clearing combined with high-resolution confocal imaging is a cutting-edge approach for dissecting the three-dimensional(3D)architecture of tissues and deciphering cellular spatial interactions under physiological and pathological conditions.Deciphering the spatial interaction of leptin receptor-expressing(LepR^(+))stromal cells with other compartments in the bone marrow is crucial for a deeper understanding of the stem cell niche and the skeletal tissue.In this study,we introduce an optimized protocol for the 3D analysis of skeletal tissues,enabling the visualization of hematopoietic and stromal cells,especially LepR+stromal cells,within optically cleared bone hemisections.Our method preserves the 3D tissue architecture and is extendable to other hematopoietic sites such as calvaria and vertebrae.The protocol entails tissue fixation,decalcification,and cryosectioning to reveal the marrow cavity.Completed within approximately 12 days,this process yields highly transparent tissues that maintain genetically encoded or antibody-stained fluorescent signals.The bone hemisections are compatible with diverse antibody labeling strategies.Confocal microscopy of these transparent samples allows for qualitative and quantitative image analysis using Aivia or Bitplane Imaris software,assessing a spectrum of parameters.With proper storage,the fluorescent signal in the stained and cleared bone hemisections remains intact for at least 2–3 months.This protocol is robust,straightforward to implement,and highly reproducible,offering a valuable tool for tissue architecture and cellular interaction studies.展开更多
Compared with the first and second generations SiC fibers, the third generation SiC fibers have obvious improvement in heat-resistance, oxidation-resistance and creep-resistance, which promote the development of SiCf/...Compared with the first and second generations SiC fibers, the third generation SiC fibers have obvious improvement in heat-resistance, oxidation-resistance and creep-resistance, which promote the development of SiCf/SiC composite materials. Therefore, the third generation SiC fibers have more advantages and broader prospects in engineering applications. In this paper, the fabrication and properties of the third generation SiC fibers are compared and discussed. The preparation processes of the third generation SiC fibers reinforced SiC matrix composites and their application in aeroengine and nuclear energy fields are summarized, while their future development is prospected as well.展开更多
Robust quantum cascade laser(QCL)enduring high temperature continuous-wave(CW)operation is of critical importance for some applications.We report on the realization of lattice-matched InGaAs/InAlAs/InP QCL materials g...Robust quantum cascade laser(QCL)enduring high temperature continuous-wave(CW)operation is of critical importance for some applications.We report on the realization of lattice-matched InGaAs/InAlAs/InP QCL materials grown by metal-organic chemical vapor deposition(MOCVD).High interface quality structures designed for light emission at 8.5μm are achieved by optimizing and precise controlling of growth conditions.A CW output power of 1.04 W at 288 K was obtained from a 4 mm-long and 10μm-wide coated laser.Corresponding maximum wall-plug efficiency and threshold current density were 7.1%and 1.18 kA/cm2,respectively.The device can operate in CW mode up to 408 K with an output power of 160 mW.展开更多
Maffucci syndrome is a congenital, non-hereditary mesodermal dysplasia manifested by multiple enchondromas and hemangiomas. It is associated with diverse secondary musculoskeletal deformities, which is exceedingly rar...Maffucci syndrome is a congenital, non-hereditary mesodermal dysplasia manifested by multiple enchondromas and hemangiomas. It is associated with diverse secondary musculoskeletal deformities, which is exceedingly rare. We report a case of hemangiomas and enchondromas localized in the unilateral limb in a patient with Maffucci syndrome. Treatment consists of orthopedic and surgical intervention to minimize deformities and for cosmetic purpose. Careful surveillance for malignant degeneration of both skeletal and non-skeletal tumors, especially in the brain and abdomen, is essential.展开更多
Electrically-pumped semiconductor lasers based on monolithic chip configuration possess plenty of advantages such as small volume,light weight,long lifetime and stable performance.Nevertheless this type of lasers rely...Electrically-pumped semiconductor lasers based on monolithic chip configuration possess plenty of advantages such as small volume,light weight,long lifetime and stable performance.Nevertheless this type of lasers rely on the interband transition,which sets the bounds for emission wavelength typically below 4μm,and state of the art performance has been attained below 3μm.Attempts to employ small bandgap meterials like antimonide or lead salts ended with poor performance mainly due to imperfect crystal quality and severe Auger recombination.In view of the broad application prospects of infrared spectral range above 3μm,more attention was casted again on the low-dimensional quantum structure materials,such as quantum wells and quantum dots,which have been applied in the near infrared successfully decades ago.展开更多
The exposed crystal facet of TiO_(2) is a crucial factor influencing the gas sensing properties.TiO_(2) with high-energy{001}crystal facets that have higher surface energy and reactivity is expected to exhibit excelle...The exposed crystal facet of TiO_(2) is a crucial factor influencing the gas sensing properties.TiO_(2) with high-energy{001}crystal facets that have higher surface energy and reactivity is expected to exhibit excellent gas-sensing properties.In this paper,TiO_(2) nanoplates with defective{001}facets were synthesized by chemical etching via one-step hydrothermal method.We carefully explored the gas-sensing performance of TiO_(2) nanoplates with defective and complete{001}facets towards acetone.The results show that the sensing response of TiO_(2) nanoplates with complete{001}facets is 70%higher than that of defective TiO_(2) nanoplates,which proves that the{001}facets plays a vital role in improving the gas sensing performance of TiO_(2).It is speculated that the poor gas sensitivity of defective TiO_(2) can be contributed to fewer adsorption sites and blocked electron transfer.This work presents a more direct evidence for explaining the important role of the complete{001}crystal facets in high sensitivity of TiO_(2) and also provides a new insight for preparing high sensitivity sensing materials.展开更多
We demonstrated a scheme of phase-locked terahertz quantum cascade lasers(THz QCLs)array,with a single-mode pulse power of 108 mW at 13 K.The device utilizes a Talbot cavity to achieve phase locking among five ridge l...We demonstrated a scheme of phase-locked terahertz quantum cascade lasers(THz QCLs)array,with a single-mode pulse power of 108 mW at 13 K.The device utilizes a Talbot cavity to achieve phase locking among five ridge lasers with first-order buried distributed feedback(DFB)grating,resulting in nearly five times amplification of the single-mode power.Due to the optimum length of Talbot cavity depends on wavelength,the combination of Talbot cavity with the DFB grating leads to better power amplification than the combination with multimode Fabry-Perot(F-P)cavities.The Talbot cavity facet reflects light back to the ridge array direction and achieves self-imaging in the array,enabling phase-locked operation of ridges.We set the spacing between adjacent elements to be 220μm,much larger than the free-space wavelength,ensuring the operation of the fundamental supermode throughout the laser's dynamic range and obtaining a high-brightness far-field distribution.This scheme provides a new approach for enhancing the single-mode power of THz QCLs.展开更多
State-of-the-art AlGaN/GaN high electron mobility structures were grown on semi-insulating 4H-SiC substrates by MOCVD and X-band microwave power high electron mobility transistors were fabricated and characterized.Hal...State-of-the-art AlGaN/GaN high electron mobility structures were grown on semi-insulating 4H-SiC substrates by MOCVD and X-band microwave power high electron mobility transistors were fabricated and characterized.Hall mobility of 2291.1 cm^(2)/(V·s)and two-dimensional electron gas density of 9.954×10^(12)cm^(-2)were achieved at 300 K.The HEMT devices with a 0.45-μm gate length exhibited maximum drain current density as high as 1039.6 mA/mm and peak extrinsic transconductance of 229.7 mS/mm.The f_(T)of 30.89 GHz and f_(max)of 38.71 GHz were measured on the device.Load-pull measurements were performed and analyzed under(-3.5,28)V,(-3.5,34)V and(-3.5,40)V gate/drain direct current bias in class-AB,respectively.The uncooled device showed high linear power gain of 17.04 dB and high power-added efficiency of 50.56%at 8 GHz when drain biased at(-3.5,28)V.In addition,when drain biased at(-3.5,40)V,the device exhibited a saturation output power dens-ity up to 6.21 W/mm at 8 GHz,with a power gain of 11.94 dB and a power-added efficiency of 39.56%.Furthermore,the low f_(max)/f_(T)ratio and the variation of the power sweep of the device at 8 GHz with drain bias voltage were analyzed.展开更多
Quantum cascade(QC)superluminescent light emitters(SLEs)have emerged as desirable broadband mid-infrared(MIR)light sources for growing number of applications in areas like medical imaging,gas sensing and national defe...Quantum cascade(QC)superluminescent light emitters(SLEs)have emerged as desirable broadband mid-infrared(MIR)light sources for growing number of applications in areas like medical imaging,gas sensing and national defense.However,it is challenging to obtain a practical high-power device due to the very low efficiency of spontaneous emission in the intersubband transitions in QC structures.Herein a design of^5μm SLEs is demonstrated with a two-phonon resonancebased QC active structure coupled with a compact combinatorial waveguide structure which comprises a short straight part adjacent to a tilted stripe and to a J-shaped waveguide.The as-fabricated SLEs achieve a high output power of 1.8 mW,exhibiting the potential to be integrated into array devices without taking up too much chip space.These results may facilitate the realization of SLE arrays to attain larger output power and pave the pathway towards the practical applications of broadband MIR light sources.展开更多
In this work,we demonstrated high-power quantum cascade laser(QCL)arrays lasing at λ~5μm by employing an optimized coupled-ridge waveguide(CRW)structure.Five-element QCL arrays were simulated and fabricated through ...In this work,we demonstrated high-power quantum cascade laser(QCL)arrays lasing at λ~5μm by employing an optimized coupled-ridge waveguide(CRW)structure.Five-element QCL arrays were simulated and fabricated through a two-step etching method to extend the CRW structure to a mid-wave infrared regime.A lateral far-field with the main peak near a diffraction-limited intensity curve of about 10°was observed by properly designing a geometric shape of the ridges and interspaces.By introducing a buried 2nd-order distributed feedback(DFB)grating,substrate emission with a radiation power above 1 W at 25℃ is achieved.Single longitudinal mode operation is obtained by changing the temperature of the heatsink with a good linear wavelength tuning coefficient of -0.2 cm^(-1)/K.展开更多
Sharing the advantages of high optical power,high efficiency and design flexibility in a compact size,quantum cascade lasers(QCLs)are excellent mid-to-far infrared laser sources for gas sensing,infrared spectroscopic,...Sharing the advantages of high optical power,high efficiency and design flexibility in a compact size,quantum cascade lasers(QCLs)are excellent mid-to-far infrared laser sources for gas sensing,infrared spectroscopic,medical diagnosis,and defense applications.Metalorganic chemical vapor deposition(MOCVD)is an important technology for growing high quality semiconductor materials,and has achieved great success in the semiconductor industry due to its advantages of high efficiency,short maintenance cycles,and high stability and repeatability.The utilization of MOCVD for the growth of QCL materials holds a significant meaning for promoting the large batch production and industrial application of QCL devices.This review summarizes the recent progress of QCLs grown by MOCVD.Material quality and the structure design together determine the device performance.Research progress on the performance improvement of MOCVD-grown QCLs based on the optimization of material quality and active region structure are mainly reviewed.展开更多
We demonstrate the use of an infrared modulated photoluminescence(PL)method based on a step-scan Fourier-transform infrared spectrometer to analyze intersubband transition(ISBT)of InGaAs/InAlAs quantum cascade detecto...We demonstrate the use of an infrared modulated photoluminescence(PL)method based on a step-scan Fourier-transform infrared spectrometer to analyze intersubband transition(ISBT)of InGaAs/InAlAs quantum cascade detector(QCD)structures.By configuring oblique and parallel excitation geometries,high signal-to-noise ratio PL spectra in near-to-far-infrared region are measured.With support from numerical calculations based on the k·p perturbation theory,the spectra is attributed to intraband and interband transitions of InGaAs/InAlAs QCD structures.Temperature evolution results show that the k-dependent transitions caused by longitudinal optical phonon-assisted scattering(Frohlich interaction)plays an important role in the ISBT.These results suggest that this infrared modulated-PL method has great potential in characterizing QCD devices and conducting performance diagnostics.展开更多
Optical reflection anisotropy microscopy mappings of micropipe defects on the surface of a 4H-SiC single crystal are studied by the scanning anisotropy microscopy(SAM)system.The reflection anisotropy(RA)image with a&#...Optical reflection anisotropy microscopy mappings of micropipe defects on the surface of a 4H-SiC single crystal are studied by the scanning anisotropy microscopy(SAM)system.The reflection anisotropy(RA)image with a'butterfly pattern'is obtained around the micropipes by SAM.The RA image of the edge dislocations is theoretically simulated based on dislocation theory and the photoelastic principle.By comparing with the Raman spectrum,it is verified that the micropipes consist of edge dislocations.The different patterns of the RA images are due to the different orientations of the Burgers vectors.Besides,the strain distribution of the micropipes is also deduced.One can identify the dislocation type,the direction of the Burgers vector and the optical anisotropy from the RA image by using SAM.Therefore,SAM is an ideal tool to measure the optical anisotropy induced by the strain field around a defect.展开更多
Background:The optimal antidepressant dosages remain controversial.This study aimed to analyze the efficacy of antidepressants and characterize their dose-response relationships in the treatments of major depressive d...Background:The optimal antidepressant dosages remain controversial.This study aimed to analyze the efficacy of antidepressants and characterize their dose-response relationships in the treatments of major depressive disorders(MDD).Methods:We searched multiple databases,including the Embase,Cochrane Central Register of Controlled Trials,PubMed,and Web of Science,for the studies that were conducted between January 8,2016,and April 30,2023.The studies are double-blinded,randomized controlled trials(RCTs)involving the adults(≥18 years)with MDD.The primary outcomes were efficacy of antidepressant and the dose-response relationships.A frequentist network meta-analysis was conducted,treating participants with various dosages of the same antidepressant as a single therapy.We also implemented the model-based meta-analysis(MBMA)using a Bayesian method to explore the dose-response relationships.Results:The network meta-analysis comprised 135,180 participants from 602 studies.All the antidepressants were more effective than the placebo;toludesvenlafaxine had the highest odds ratio(OR)of 4.52(95%confidence interval[CI]:2.65-7.72),and reboxetine had the lowest OR of 1.34(95%CI:1.14-1.57).Moreover,amitriptyline,clomipramine,and reboxetine showed a linear increase in effect size from low to high doses.The effect size of toludesvenlafaxine increased significantly up to 80 mg/day and subsequently maintained the maximal dose up to 160 mg/day while the predictive curves of nefazodone were fairly flat in different dosages.Conclusions:Although most antidepressants were more efficacious than placebo in treating MDD,no consistent dose-response relationship between any antidepressants was observed.For most antidepressants,the maximum efficacy was achieved at lower or middle prescribed doses,rather than at the upper limit.展开更多
Pyroptosis,a novel form of inflammation-related programmed cell death that often occurs in myeloid cells,plays an important role in multiple inflammatory diseases.Our previous study revealed macrophage dysfunction in ...Pyroptosis,a novel form of inflammation-related programmed cell death that often occurs in myeloid cells,plays an important role in multiple inflammatory diseases.Our previous study revealed macrophage dysfunction in acute graft-versus-host disease(a GVHD).However,whether macrophages undergo pyroptosis in a GVHD remains unknown.In our study,macrophage pyroptosis was observed in a GVHD mice.Additionally,serum IL-1βand IL-18 levels were increased in a GVHD patients.Almost all peritoneal macrophages in the a GVHD mice were derived from the donors.Less pathological damage and a longer survival time were observed in the mice that received purified T cells and bone marrow(BM)from AAV9-F4/80-GSDMD mice,indicating that macrophage pyroptosis in donor mice promoted the development of a GVHD.In addition,decreased proportions of CD69^(+)CD4^(+)T cells,Th1 cells and Th17 cells and an increased proportion of Tregs were observed in the recipients when GSDMD was suppressed in the donor macrophages.Administration of a pyroptosis inhibitor significantly alleviated the severity of a GVHD without impairing graft-versus-lymphoma(GVL)effects.Our results suggested that donor-derived macrophages undergo pyroptosis in a GVHD,and these cells might participate in the development of a GVHD by affecting the activation and differentiation of CD4^(+)cells.The pyroptosis inhibitor disulfiram is a potentially promising agent for a GVHD treatment.展开更多
基金supported by the Ministry of Science and Technology of the People’s Republic of China(Grant No.2022YFC2808203)the National Natural Science Foundation of China(Grant Nos.11474254 and 11804298).
文摘Based on the first-order correlation function of light,we propose analogous optical coherent states(AOCSs)sourced by partially coherent beams,which can nondiffractively propagate with sinusoidal oscillation in the harmonic potential when the nondiffraction propagation matching condition(NPMC)is met.Unlike the traditional quantum coherent state,the minimum uncertainty of AOCS is related to the coherence of light,and only when the NPMC is met,its uncertainty is the least.Furthermore,based on the mathematical similarity between the Schrödinger and the Helmholtz equations,we find that our proposed AOCSs correspond to the partially coherent steady states of the harmonic oscillator.Our research not only increases the understanding of the coherence of light and enriches the types of nondiffraction beams but also increases the understanding of the quantum coherence regulating the evolution of probability waves.
基金National Natural Science Foundation of China(grant number 82272563 to B.S.)National Science and Technology Major Project of the Ministry of Science and Technology of China(grant number 2023ZD0501202 to B.S.)+4 种基金institutional grants allocated to the National Institute of Biological Sciences,Beijing(NIBS)from the Chinese Ministry of Science and Technology,Beijing Municipal Commission of Science and Technology,and Tsinghua Universitythe support from China Pharmaceutical University(grant number 3150140001 to S.F.)National Natural Science Foundation of China(grant numbers 82203653 to S.F.,82371957 to L.W.,and 82371956 to X.C.)Beijing Municipal Public Welfare Development and Reform Pilot Project for Medical Research Institutes(grant number JYY2023-8 to X.C.)Research Grants Council of University Grants Committee Hong Kong(grant numbers 14113723,14108720,14121721,14202920,N_CUHK472/22,C7030-18G,T13-402/17-N,and AoE/M-402/20)。
文摘Tissue clearing combined with high-resolution confocal imaging is a cutting-edge approach for dissecting the three-dimensional(3D)architecture of tissues and deciphering cellular spatial interactions under physiological and pathological conditions.Deciphering the spatial interaction of leptin receptor-expressing(LepR^(+))stromal cells with other compartments in the bone marrow is crucial for a deeper understanding of the stem cell niche and the skeletal tissue.In this study,we introduce an optimized protocol for the 3D analysis of skeletal tissues,enabling the visualization of hematopoietic and stromal cells,especially LepR+stromal cells,within optically cleared bone hemisections.Our method preserves the 3D tissue architecture and is extendable to other hematopoietic sites such as calvaria and vertebrae.The protocol entails tissue fixation,decalcification,and cryosectioning to reveal the marrow cavity.Completed within approximately 12 days,this process yields highly transparent tissues that maintain genetically encoded or antibody-stained fluorescent signals.The bone hemisections are compatible with diverse antibody labeling strategies.Confocal microscopy of these transparent samples allows for qualitative and quantitative image analysis using Aivia or Bitplane Imaris software,assessing a spectrum of parameters.With proper storage,the fluorescent signal in the stained and cleared bone hemisections remains intact for at least 2–3 months.This protocol is robust,straightforward to implement,and highly reproducible,offering a valuable tool for tissue architecture and cellular interaction studies.
文摘Compared with the first and second generations SiC fibers, the third generation SiC fibers have obvious improvement in heat-resistance, oxidation-resistance and creep-resistance, which promote the development of SiCf/SiC composite materials. Therefore, the third generation SiC fibers have more advantages and broader prospects in engineering applications. In this paper, the fabrication and properties of the third generation SiC fibers are compared and discussed. The preparation processes of the third generation SiC fibers reinforced SiC matrix composites and their application in aeroengine and nuclear energy fields are summarized, while their future development is prospected as well.
基金The authors would thank Ping Liang and Ying Hu for their help with device fabrication.This work was supported by the National Key Research and Development Program of China(Grant No.2020YFB0408401)in part by the National Natural Science Foundation of China(Grant Nos.61991430,61774146,61790583,61734006,61835011,61674144,61774150,61805168)+1 种基金in part by Beijing Municipal Science&Technology Commission(Grant No.Z201100004020006)in part by the Key Projects of the Chinese Academy of Sciences(Grant Nos.2018147,YJKYYQ20190002,QYZDJ-SSW-JSC027,XDB43000000,ZDKYYQ20200006).
文摘Robust quantum cascade laser(QCL)enduring high temperature continuous-wave(CW)operation is of critical importance for some applications.We report on the realization of lattice-matched InGaAs/InAlAs/InP QCL materials grown by metal-organic chemical vapor deposition(MOCVD).High interface quality structures designed for light emission at 8.5μm are achieved by optimizing and precise controlling of growth conditions.A CW output power of 1.04 W at 288 K was obtained from a 4 mm-long and 10μm-wide coated laser.Corresponding maximum wall-plug efficiency and threshold current density were 7.1%and 1.18 kA/cm2,respectively.The device can operate in CW mode up to 408 K with an output power of 160 mW.
文摘Maffucci syndrome is a congenital, non-hereditary mesodermal dysplasia manifested by multiple enchondromas and hemangiomas. It is associated with diverse secondary musculoskeletal deformities, which is exceedingly rare. We report a case of hemangiomas and enchondromas localized in the unilateral limb in a patient with Maffucci syndrome. Treatment consists of orthopedic and surgical intervention to minimize deformities and for cosmetic purpose. Careful surveillance for malignant degeneration of both skeletal and non-skeletal tumors, especially in the brain and abdomen, is essential.
文摘Electrically-pumped semiconductor lasers based on monolithic chip configuration possess plenty of advantages such as small volume,light weight,long lifetime and stable performance.Nevertheless this type of lasers rely on the interband transition,which sets the bounds for emission wavelength typically below 4μm,and state of the art performance has been attained below 3μm.Attempts to employ small bandgap meterials like antimonide or lead salts ended with poor performance mainly due to imperfect crystal quality and severe Auger recombination.In view of the broad application prospects of infrared spectral range above 3μm,more attention was casted again on the low-dimensional quantum structure materials,such as quantum wells and quantum dots,which have been applied in the near infrared successfully decades ago.
基金financially supported by the National Natural Science Foundation of China(Nos.51773226,61701514)the Natural Science Foundation of Hunan Province(No.2018JJ3603)
文摘The exposed crystal facet of TiO_(2) is a crucial factor influencing the gas sensing properties.TiO_(2) with high-energy{001}crystal facets that have higher surface energy and reactivity is expected to exhibit excellent gas-sensing properties.In this paper,TiO_(2) nanoplates with defective{001}facets were synthesized by chemical etching via one-step hydrothermal method.We carefully explored the gas-sensing performance of TiO_(2) nanoplates with defective and complete{001}facets towards acetone.The results show that the sensing response of TiO_(2) nanoplates with complete{001}facets is 70%higher than that of defective TiO_(2) nanoplates,which proves that the{001}facets plays a vital role in improving the gas sensing performance of TiO_(2).It is speculated that the poor gas sensitivity of defective TiO_(2) can be contributed to fewer adsorption sites and blocked electron transfer.This work presents a more direct evidence for explaining the important role of the complete{001}crystal facets in high sensitivity of TiO_(2) and also provides a new insight for preparing high sensitivity sensing materials.
基金funded by National Natural Science Foundation of China, grant numbers 62335006, 62274014, 62235016, 61734006, 61835011, 61991430funded by Key Program of the Chinese Academy of Sciences, grant numbers XDB43000000, QYZDJSSW-JSC027Beijing Municipal Science & Technology Commission, grant number Z221100002722018
文摘We demonstrated a scheme of phase-locked terahertz quantum cascade lasers(THz QCLs)array,with a single-mode pulse power of 108 mW at 13 K.The device utilizes a Talbot cavity to achieve phase locking among five ridge lasers with first-order buried distributed feedback(DFB)grating,resulting in nearly five times amplification of the single-mode power.Due to the optimum length of Talbot cavity depends on wavelength,the combination of Talbot cavity with the DFB grating leads to better power amplification than the combination with multimode Fabry-Perot(F-P)cavities.The Talbot cavity facet reflects light back to the ridge array direction and achieves self-imaging in the array,enabling phase-locked operation of ridges.We set the spacing between adjacent elements to be 220μm,much larger than the free-space wavelength,ensuring the operation of the fundamental supermode throughout the laser's dynamic range and obtaining a high-brightness far-field distribution.This scheme provides a new approach for enhancing the single-mode power of THz QCLs.
基金supported by the National Key Research and Development Program of China(2017YFB0402900)the Key-Area Research and Development Program of Guangdong Province(2019B010126001)+3 种基金the Natural Science Foundation for Distinguished Young Scholars of Shandong Province(ZR2019JQ01)the National Natural Sciences Foundation of China(62074144,52022052,62004118)Key R&D plan of Shandong Province(2019JMRH0901,2019JMRH0201)the Natural Science Foundation of Shandong Province(ZR2019BEM030,ZR2019BEM011).
文摘State-of-the-art AlGaN/GaN high electron mobility structures were grown on semi-insulating 4H-SiC substrates by MOCVD and X-band microwave power high electron mobility transistors were fabricated and characterized.Hall mobility of 2291.1 cm^(2)/(V·s)and two-dimensional electron gas density of 9.954×10^(12)cm^(-2)were achieved at 300 K.The HEMT devices with a 0.45-μm gate length exhibited maximum drain current density as high as 1039.6 mA/mm and peak extrinsic transconductance of 229.7 mS/mm.The f_(T)of 30.89 GHz and f_(max)of 38.71 GHz were measured on the device.Load-pull measurements were performed and analyzed under(-3.5,28)V,(-3.5,34)V and(-3.5,40)V gate/drain direct current bias in class-AB,respectively.The uncooled device showed high linear power gain of 17.04 dB and high power-added efficiency of 50.56%at 8 GHz when drain biased at(-3.5,28)V.In addition,when drain biased at(-3.5,40)V,the device exhibited a saturation output power dens-ity up to 6.21 W/mm at 8 GHz,with a power gain of 11.94 dB and a power-added efficiency of 39.56%.Furthermore,the low f_(max)/f_(T)ratio and the variation of the power sweep of the device at 8 GHz with drain bias voltage were analyzed.
基金supported by the Key Research and Development Plan of Ministry of Science and Technology(No.2016YFB0402303)the National Natural Science Foundation of China(No.61575222)+1 种基金the open project of the State Key Laboratory of Luminescence and ApplicationsChina Postdoctoral Science Foundation(No.2017M621858)
文摘Quantum cascade(QC)superluminescent light emitters(SLEs)have emerged as desirable broadband mid-infrared(MIR)light sources for growing number of applications in areas like medical imaging,gas sensing and national defense.However,it is challenging to obtain a practical high-power device due to the very low efficiency of spontaneous emission in the intersubband transitions in QC structures.Herein a design of^5μm SLEs is demonstrated with a two-phonon resonancebased QC active structure coupled with a compact combinatorial waveguide structure which comprises a short straight part adjacent to a tilted stripe and to a J-shaped waveguide.The as-fabricated SLEs achieve a high output power of 1.8 mW,exhibiting the potential to be integrated into array devices without taking up too much chip space.These results may facilitate the realization of SLE arrays to attain larger output power and pave the pathway towards the practical applications of broadband MIR light sources.
基金supported by National Basic Research Program of China(Grant Nos.2018YFA0209103,2018YFB2200504)in part by National Natural Science Foundation of China(Grant Nos.61991430,61774146,61790583,61734006,61835011,61674144,61774150,61805168)+1 种基金in part by Beijing Municipal Science&Technology Commission(Grant No.Z201100004020006)in part by the Key projects of the Chinese Academy of Sciences(Grant No.2018147,Grant No.YJKYYQ20190002,Grant No.QYZDJ-SSW-JSC027,Grant No.XDB43000000,Grant No.ZDKYYQ20200006).
文摘In this work,we demonstrated high-power quantum cascade laser(QCL)arrays lasing at λ~5μm by employing an optimized coupled-ridge waveguide(CRW)structure.Five-element QCL arrays were simulated and fabricated through a two-step etching method to extend the CRW structure to a mid-wave infrared regime.A lateral far-field with the main peak near a diffraction-limited intensity curve of about 10°was observed by properly designing a geometric shape of the ridges and interspaces.By introducing a buried 2nd-order distributed feedback(DFB)grating,substrate emission with a radiation power above 1 W at 25℃ is achieved.Single longitudinal mode operation is obtained by changing the temperature of the heatsink with a good linear wavelength tuning coefficient of -0.2 cm^(-1)/K.
基金supported by National Key Research and Development Program of China (Grant No.2021YFB3201900)National Natural Science Foundation of China (Grant Nos.61991430,62235016)+1 种基金Youth Innovation Promotion Association of CAS (Grant Nos.2022112,Y2022046)Key projects of the Chinese Academy of Sciences (Grant No.XDB43000000)。
文摘Sharing the advantages of high optical power,high efficiency and design flexibility in a compact size,quantum cascade lasers(QCLs)are excellent mid-to-far infrared laser sources for gas sensing,infrared spectroscopic,medical diagnosis,and defense applications.Metalorganic chemical vapor deposition(MOCVD)is an important technology for growing high quality semiconductor materials,and has achieved great success in the semiconductor industry due to its advantages of high efficiency,short maintenance cycles,and high stability and repeatability.The utilization of MOCVD for the growth of QCL materials holds a significant meaning for promoting the large batch production and industrial application of QCL devices.This review summarizes the recent progress of QCLs grown by MOCVD.Material quality and the structure design together determine the device performance.Research progress on the performance improvement of MOCVD-grown QCLs based on the optimization of material quality and active region structure are mainly reviewed.
基金supported by the National Key Research and Development Program of China(Grant No.2019YFB2203400)the National Natural Science Foundation of China(Grant Nos.61974044 and 11974368)the Shanghai Committee of Science and Technology of China(Grant Nos.20142201000 and 21ZR1421500)。
文摘We demonstrate the use of an infrared modulated photoluminescence(PL)method based on a step-scan Fourier-transform infrared spectrometer to analyze intersubband transition(ISBT)of InGaAs/InAlAs quantum cascade detector(QCD)structures.By configuring oblique and parallel excitation geometries,high signal-to-noise ratio PL spectra in near-to-far-infrared region are measured.With support from numerical calculations based on the k·p perturbation theory,the spectra is attributed to intraband and interband transitions of InGaAs/InAlAs QCD structures.Temperature evolution results show that the k-dependent transitions caused by longitudinal optical phonon-assisted scattering(Frohlich interaction)plays an important role in the ISBT.These results suggest that this infrared modulated-PL method has great potential in characterizing QCD devices and conducting performance diagnostics.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2018YFE0204001,2018YFA0209103,2016YFB0400101,and 2016YFB0402303)the National Natural Science Foundation of China(Grant Nos.61627822,61704121,61991430,and 62074036)Postdoctoral Research Program of Jiangsu Province(Grant No.2021K599C).
文摘Optical reflection anisotropy microscopy mappings of micropipe defects on the surface of a 4H-SiC single crystal are studied by the scanning anisotropy microscopy(SAM)system.The reflection anisotropy(RA)image with a'butterfly pattern'is obtained around the micropipes by SAM.The RA image of the edge dislocations is theoretically simulated based on dislocation theory and the photoelastic principle.By comparing with the Raman spectrum,it is verified that the micropipes consist of edge dislocations.The different patterns of the RA images are due to the different orientations of the Burgers vectors.Besides,the strain distribution of the micropipes is also deduced.One can identify the dislocation type,the direction of the Burgers vector and the optical anisotropy from the RA image by using SAM.Therefore,SAM is an ideal tool to measure the optical anisotropy induced by the strain field around a defect.
基金This work was supported by grants from the National Natural Science Foundation of China(No.72074011)Special Project for Director,China Center for Evidence-Based Traditional Chinese Medicine(No.2020YJSZX-2)+1 种基金the second batch of Key Projects of Scientific Act for Drug Regulation of China(No.[2021]37-10)Sci-Tech Innovation 2030-Major Project of Brain Science and Brain-Inspired Intelligence Technology(No.2021ZD0200600).
文摘Background:The optimal antidepressant dosages remain controversial.This study aimed to analyze the efficacy of antidepressants and characterize their dose-response relationships in the treatments of major depressive disorders(MDD).Methods:We searched multiple databases,including the Embase,Cochrane Central Register of Controlled Trials,PubMed,and Web of Science,for the studies that were conducted between January 8,2016,and April 30,2023.The studies are double-blinded,randomized controlled trials(RCTs)involving the adults(≥18 years)with MDD.The primary outcomes were efficacy of antidepressant and the dose-response relationships.A frequentist network meta-analysis was conducted,treating participants with various dosages of the same antidepressant as a single therapy.We also implemented the model-based meta-analysis(MBMA)using a Bayesian method to explore the dose-response relationships.Results:The network meta-analysis comprised 135,180 participants from 602 studies.All the antidepressants were more effective than the placebo;toludesvenlafaxine had the highest odds ratio(OR)of 4.52(95%confidence interval[CI]:2.65-7.72),and reboxetine had the lowest OR of 1.34(95%CI:1.14-1.57).Moreover,amitriptyline,clomipramine,and reboxetine showed a linear increase in effect size from low to high doses.The effect size of toludesvenlafaxine increased significantly up to 80 mg/day and subsequently maintained the maximal dose up to 160 mg/day while the predictive curves of nefazodone were fairly flat in different dosages.Conclusions:Although most antidepressants were more efficacious than placebo in treating MDD,no consistent dose-response relationship between any antidepressants was observed.For most antidepressants,the maximum efficacy was achieved at lower or middle prescribed doses,rather than at the upper limit.
基金supported by the National Key Research and Development Program of China(2023YFC2507803)the National Natural Science Foundation of China(82300247,82430006,82230004,82130008)+1 种基金Beijing Natural Science Foundation(L248044,7242154,7232188)Beijing Tongzhou Science and Technology Foundation(CXTD2024005)。
文摘Pyroptosis,a novel form of inflammation-related programmed cell death that often occurs in myeloid cells,plays an important role in multiple inflammatory diseases.Our previous study revealed macrophage dysfunction in acute graft-versus-host disease(a GVHD).However,whether macrophages undergo pyroptosis in a GVHD remains unknown.In our study,macrophage pyroptosis was observed in a GVHD mice.Additionally,serum IL-1βand IL-18 levels were increased in a GVHD patients.Almost all peritoneal macrophages in the a GVHD mice were derived from the donors.Less pathological damage and a longer survival time were observed in the mice that received purified T cells and bone marrow(BM)from AAV9-F4/80-GSDMD mice,indicating that macrophage pyroptosis in donor mice promoted the development of a GVHD.In addition,decreased proportions of CD69^(+)CD4^(+)T cells,Th1 cells and Th17 cells and an increased proportion of Tregs were observed in the recipients when GSDMD was suppressed in the donor macrophages.Administration of a pyroptosis inhibitor significantly alleviated the severity of a GVHD without impairing graft-versus-lymphoma(GVL)effects.Our results suggested that donor-derived macrophages undergo pyroptosis in a GVHD,and these cells might participate in the development of a GVHD by affecting the activation and differentiation of CD4^(+)cells.The pyroptosis inhibitor disulfiram is a potentially promising agent for a GVHD treatment.
