The effect of nano diamond(ND)content on the microstructure,mechanical properties,and thermal conductivity of ZK60+x(x=0,0.05,0.1,0.15,0.2 wt.%)ND composites were investigated.The microstructures of ND/ZK60 composites...The effect of nano diamond(ND)content on the microstructure,mechanical properties,and thermal conductivity of ZK60+x(x=0,0.05,0.1,0.15,0.2 wt.%)ND composites were investigated.The microstructures of ND/ZK60 composites were observed,which indicated that the nanoscale MgZn_(2) and ND particles distributed evenly in theα-Mg matrix.The tensile yield strength(TYS)and compressive yield strength(CYS)of the composites first increased remarkably and then decreased with further increasing the ND content.Due to the surface area of the matrix-diamond interface increased and the grains sizes of composites decreased with the amount of ND increase,which cause the coefficient of thermal expansion(CTE)of the composites reduced significantly.Meanwhile,the thermal conductivity of the composite material decreases from 129 W·m^(−1)·K^(−1) to 116 W·m^(−1)·K^(−1) with the content of ND increasing from 0.05%to 2.0%.The thermal conductivity of the composites increases to the maximum and then decrease with the increase of temperature(in temperature range of 273-573 K).The ZK60+0.05 ND showed superior mechanical and thermal conductivity property,TYS of 343.97 MPa,CYS of 341.74 MPa,elongation of 15.71%,CTE of 7.3×10^(−6)K^(−1),and thermal conductivity of 129 W·m^(−1)·K^(−1) at room temperature.It is demonstrated that the ND content has an obvious influence on the microstructure,mechanical properties,and thermal conductivity of ND/ZK60 composites.展开更多
Since the emergence of graphene, transition metal dichalcogenides, and black phosphorus, two-dimensional materials have attracted significant attention and have driven the development of fundamental physics and optoel...Since the emergence of graphene, transition metal dichalcogenides, and black phosphorus, two-dimensional materials have attracted significant attention and have driven the development of fundamental physics and optoelectronic devices. Metal phosphorus trichalcogenides(MPX3), due to their large bandgap of 1.3–3.5 eV, enable the extension of optoelectronic applications to visible and ultraviolet(UV) wavelengths.展开更多
Introduction Cap polyposis is a rare benign disease of the digestive tract,characterized by inflammatory polyps with a cap of inflammatory granulation tissue.First described in 1985 by Williams et al.[1],cap polyposis...Introduction Cap polyposis is a rare benign disease of the digestive tract,characterized by inflammatory polyps with a cap of inflammatory granulation tissue.First described in 1985 by Williams et al.[1],cap polyposis is now still introduced in case reports.The clinical course and pathogenesis of this disease are yet to be elucidated and specific therapies have not been established.展开更多
We report on the operation of passively Q-switched waveguide lasers at 1 μm wavelength based on a graphene∕WS_2 heterostructure as a saturable absorber(SA). The gain medium is a crystalline Nd:YVO_4 cladding wavegui...We report on the operation of passively Q-switched waveguide lasers at 1 μm wavelength based on a graphene∕WS_2 heterostructure as a saturable absorber(SA). The gain medium is a crystalline Nd:YVO_4 cladding waveguide produced by femtosecond laser writing. The nanosecond waveguide laser operation at 1064 nm has been realized with the maximum average output power of 275 m W and slope efficiency of 37%. In comparison with the systems based on single WS_2 or graphene SA, the lasing Q-switched by a graphene∕WS_2 heterostructure SA possesses advantages of a higher pulse energy and enhanced slope efficiency, indicating the promisingapplications of van der Waals heterostructures for ultrafast photonic devices.展开更多
This work reports the real-time observation of the interlayer lattice vibrations in bilayer and few-layer PtSe_2 by means of the coherent phonon method. The layer-breathing mode and standing wave mode of the interlaye...This work reports the real-time observation of the interlayer lattice vibrations in bilayer and few-layer PtSe_2 by means of the coherent phonon method. The layer-breathing mode and standing wave mode of the interlayer vibrations are found to coexist in such a kind of group-10 transition metal dichalcogenides(TMDCs). The interlayer breathing force constant standing for perpendicular coupling(per effective atom) is derived as 7.5 N/m,2.5 times larger than that of graphene. The interlayer shearing force constant is comparable to the interlayer breathing force constant, which indicates that PtSe2 has nearly isotropic interlayer coupling. The low-frequency Raman spectroscopy elucidates the polarization behavior of the layer-breathing mode that is assigned to have A1 g symmetry. The standing wave mode shows redshift with the increasing number of layers, which successfully determines the out-of-plane sound velocity of PtSe2 experimentally. Our results manifest that the coherent phonon method is a good tool to uncover the interlayer lattice vibrations, beyond the conventional Raman spectroscopy limit. The strong interlayer interaction in group-10 TMDCs reveals their promising potential in high-frequency(~terahertz) micro-mechanical resonators.展开更多
Questions hovering over the modulation of bandgap size and excitonic effect on nonlinear absorption in twodimensional transition metal dichalcogenides (TMDCs) have restricted their application in micro/nano optical mo...Questions hovering over the modulation of bandgap size and excitonic effect on nonlinear absorption in twodimensional transition metal dichalcogenides (TMDCs) have restricted their application in micro/nano optical modulator, optical switching, and beam shaping devices. Here, degenerate two-photon absorption (TPA) in the near-infrared region was studied experimentally in mechanically exfoliated MoS2 from single layer to multilayer. The layer-dependent TPA coefficients were significantly modulated by the detuning of the excitonic dark state (2p). The shift of the quasiparticle bandgap and the decreasing of exciton binding energy with layers were deduced, combined with the non-hydrogen model of excitons in TMDCs and the scaling rule of semiconductors. Our work clearly demonstrates the layer modulation of nonlinear absorption in TMDCs and provides support for layer-dependent nonlinear optical devices, such as optical limiters and optical switches.展开更多
Copper(Cu)nanoparticles(NPs)are synthesized under the near-surface region of the Nd∶Y_(3)Al_(5)O_(12)(Nd:YAG)crystal by direct Cu^(+)ions implantation.Subsequently,the monolithic ridge waveguide with embedded Cu NPs ...Copper(Cu)nanoparticles(NPs)are synthesized under the near-surface region of the Nd∶Y_(3)Al_(5)O_(12)(Nd:YAG)crystal by direct Cu^(+)ions implantation.Subsequently,the monolithic ridge waveguide with embedded Cu NPs is fabricated by C^(4+)ions irradiation and diamond saw dicing.The nonlinear optical response of the sample is investigated by the Z-scan technique,and pronounced saturable absorption is observed at the 1030 nm femtosecond laser.Based on the obvious saturable absorption of Cu NPs embedded Nd:YAG crystal,1μm monolithic mode-locked pulsed waveguide laser is implemented by evanescent field interaction between NPs and waveguide modes,reaching the pulse duration of 24.8 ps and repetition rate of 7.8 GHz.The work combines waveguides with NPs,achieving pulsed laser devices based on monolithic waveguide chips.展开更多
Mechanical exfoliation(ME) and chemical vapor deposition(CVD) MoS2 monolayers have been extensively studied, but the large differences of nonlinear optical performance between them have never been clarified. Here,we p...Mechanical exfoliation(ME) and chemical vapor deposition(CVD) MoS2 monolayers have been extensively studied, but the large differences of nonlinear optical performance between them have never been clarified. Here,we prepared MoS2 monolayers using ME and CVD methods and investigated the two-photon absorption(TPA)response and its saturation. We found that the TPA coefficient of the ME monolayer was about(1.88 ± 0.21)× 10^3 cm/GW, nearly two times that of the CVD one at(1.04 ± 0.15)× 10^3 cm/GW. Furthermore,we simulated and compared the TPA-induced optical pulse modulation in multilayer cascaded structures, which is instructive and meaningful for the design of optical devices such as a beam shaper and optical limiter.展开更多
基金financial support of Qing Hai Provincial Natural Science Foundation (Grant No. 2018-ZJ949Q)。
文摘The effect of nano diamond(ND)content on the microstructure,mechanical properties,and thermal conductivity of ZK60+x(x=0,0.05,0.1,0.15,0.2 wt.%)ND composites were investigated.The microstructures of ND/ZK60 composites were observed,which indicated that the nanoscale MgZn_(2) and ND particles distributed evenly in theα-Mg matrix.The tensile yield strength(TYS)and compressive yield strength(CYS)of the composites first increased remarkably and then decreased with further increasing the ND content.Due to the surface area of the matrix-diamond interface increased and the grains sizes of composites decreased with the amount of ND increase,which cause the coefficient of thermal expansion(CTE)of the composites reduced significantly.Meanwhile,the thermal conductivity of the composite material decreases from 129 W·m^(−1)·K^(−1) to 116 W·m^(−1)·K^(−1) with the content of ND increasing from 0.05%to 2.0%.The thermal conductivity of the composites increases to the maximum and then decrease with the increase of temperature(in temperature range of 273-573 K).The ZK60+0.05 ND showed superior mechanical and thermal conductivity property,TYS of 343.97 MPa,CYS of 341.74 MPa,elongation of 15.71%,CTE of 7.3×10^(−6)K^(−1),and thermal conductivity of 129 W·m^(−1)·K^(−1) at room temperature.It is demonstrated that the ND content has an obvious influence on the microstructure,mechanical properties,and thermal conductivity of ND/ZK60 composites.
基金National Natural Science Foundation of China(12174414)Shanghai Science and Technology International Cooperation Fund (19520743900)+1 种基金Strategic Priority Research Program of Chinese Academy of Sciences(XDB43010303)China Postdoctoral Science Foundation(2023M743248)。
文摘Since the emergence of graphene, transition metal dichalcogenides, and black phosphorus, two-dimensional materials have attracted significant attention and have driven the development of fundamental physics and optoelectronic devices. Metal phosphorus trichalcogenides(MPX3), due to their large bandgap of 1.3–3.5 eV, enable the extension of optoelectronic applications to visible and ultraviolet(UV) wavelengths.
文摘Introduction Cap polyposis is a rare benign disease of the digestive tract,characterized by inflammatory polyps with a cap of inflammatory granulation tissue.First described in 1985 by Williams et al.[1],cap polyposis is now still introduced in case reports.The clinical course and pathogenesis of this disease are yet to be elucidated and specific therapies have not been established.
基金111 Project of China(B13029)Strategic Priority Research Program of CAS(XDB16030700)+2 种基金Key Research Program of Frontier Science of CAS(QYZDB-SSWJSC041)National Natural Science Foundation of China(NSFC)(11274203,61522510)STCSM Excellent Academic Leader of Shanghai(17XD1403900)
文摘We report on the operation of passively Q-switched waveguide lasers at 1 μm wavelength based on a graphene∕WS_2 heterostructure as a saturable absorber(SA). The gain medium is a crystalline Nd:YVO_4 cladding waveguide produced by femtosecond laser writing. The nanosecond waveguide laser operation at 1064 nm has been realized with the maximum average output power of 275 m W and slope efficiency of 37%. In comparison with the systems based on single WS_2 or graphene SA, the lasing Q-switched by a graphene∕WS_2 heterostructure SA possesses advantages of a higher pulse energy and enhanced slope efficiency, indicating the promisingapplications of van der Waals heterostructures for ultrafast photonic devices.
基金National Natural Science Foundation of China(11874370,61675217)Strategic Priority Research Program of Chinese Academy of Sciences(XDB16030700)+5 种基金Key Research Program of Frontier Science of Chinese Academy of Sciences(QYZDB-SSW-JSC041)Program of Shanghai Academic Research Leader(17XD1403900)Natural Science Foundation of Shanghai(18ZR1444700)Shanghai Rising-Star Program(A type 19QA1410000)Youth Innovation Promotion Association of the Chinese Academy of SciencesHigh-End Foreign Expert Fellowship of the Ministry of Science and Technology of the P.R.China(G20190161002)
文摘This work reports the real-time observation of the interlayer lattice vibrations in bilayer and few-layer PtSe_2 by means of the coherent phonon method. The layer-breathing mode and standing wave mode of the interlayer vibrations are found to coexist in such a kind of group-10 transition metal dichalcogenides(TMDCs). The interlayer breathing force constant standing for perpendicular coupling(per effective atom) is derived as 7.5 N/m,2.5 times larger than that of graphene. The interlayer shearing force constant is comparable to the interlayer breathing force constant, which indicates that PtSe2 has nearly isotropic interlayer coupling. The low-frequency Raman spectroscopy elucidates the polarization behavior of the layer-breathing mode that is assigned to have A1 g symmetry. The standing wave mode shows redshift with the increasing number of layers, which successfully determines the out-of-plane sound velocity of PtSe2 experimentally. Our results manifest that the coherent phonon method is a good tool to uncover the interlayer lattice vibrations, beyond the conventional Raman spectroscopy limit. The strong interlayer interaction in group-10 TMDCs reveals their promising potential in high-frequency(~terahertz) micro-mechanical resonators.
基金Strategic Priority Research Program of CAS(XDB16030700)Program of Shanghai Academic Research Leader(17XD1403900)+7 种基金Natural Science Foundation of Shanghai(18ZR1444700)Youth Innovation Promotion Association of the Chinese Academy of SciencesNational Natural Science Foundation of China(NSFC)(11874370,61675217,61875213)Shanghai Rising-Star Program(19QA1410000)CAS Interdisciplinary Innovation Team and National Natural Science Foundation of China(11535010)CAS Center for Excellence in Ultra-Intense Laser ScienceKey Research Program of Frontier Science of CAS(QYZDB-SSW-JSC041)President’s International Fellowship Initiative(PIFI)of CAS(2017VTA0010,2017VTB0006,2018VTB0007)
文摘Questions hovering over the modulation of bandgap size and excitonic effect on nonlinear absorption in twodimensional transition metal dichalcogenides (TMDCs) have restricted their application in micro/nano optical modulator, optical switching, and beam shaping devices. Here, degenerate two-photon absorption (TPA) in the near-infrared region was studied experimentally in mechanically exfoliated MoS2 from single layer to multilayer. The layer-dependent TPA coefficients were significantly modulated by the detuning of the excitonic dark state (2p). The shift of the quasiparticle bandgap and the decreasing of exciton binding energy with layers were deduced, combined with the non-hydrogen model of excitons in TMDCs and the scaling rule of semiconductors. Our work clearly demonstrates the layer modulation of nonlinear absorption in TMDCs and provides support for layer-dependent nonlinear optical devices, such as optical limiters and optical switches.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.11535008 and 61975221)the Major Program of Natural Science Foundation of Shandong Province(No.ZR2018ZB0649)。
文摘Copper(Cu)nanoparticles(NPs)are synthesized under the near-surface region of the Nd∶Y_(3)Al_(5)O_(12)(Nd:YAG)crystal by direct Cu^(+)ions implantation.Subsequently,the monolithic ridge waveguide with embedded Cu NPs is fabricated by C^(4+)ions irradiation and diamond saw dicing.The nonlinear optical response of the sample is investigated by the Z-scan technique,and pronounced saturable absorption is observed at the 1030 nm femtosecond laser.Based on the obvious saturable absorption of Cu NPs embedded Nd:YAG crystal,1μm monolithic mode-locked pulsed waveguide laser is implemented by evanescent field interaction between NPs and waveguide modes,reaching the pulse duration of 24.8 ps and repetition rate of 7.8 GHz.The work combines waveguides with NPs,achieving pulsed laser devices based on monolithic waveguide chips.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.61675217 and 11874370)the Strategic Priority Research Program of CAS(No.XDB16030700)+4 种基金the Key Research Program of Frontier Science of CAS(No.QYZDB-SSW-JSC041)the Program of Shanghai Academic Research Leader(No.17XD1403900)the Natural Science Foundation of Shanghai(No.18ZR1444700)the Shanghai Rising-Star Program(A Type 19QA1410000)the Youth Innovation Promotion Association,CAS
文摘Mechanical exfoliation(ME) and chemical vapor deposition(CVD) MoS2 monolayers have been extensively studied, but the large differences of nonlinear optical performance between them have never been clarified. Here,we prepared MoS2 monolayers using ME and CVD methods and investigated the two-photon absorption(TPA)response and its saturation. We found that the TPA coefficient of the ME monolayer was about(1.88 ± 0.21)× 10^3 cm/GW, nearly two times that of the CVD one at(1.04 ± 0.15)× 10^3 cm/GW. Furthermore,we simulated and compared the TPA-induced optical pulse modulation in multilayer cascaded structures, which is instructive and meaningful for the design of optical devices such as a beam shaper and optical limiter.
