This paper introduces a novel method to realize the superposition of orbital angular momentum of photons by combined computer-generated hologram （CCGH） fabricated in silica glass with femtosecond laser pulses. First...This paper introduces a novel method to realize the superposition of orbital angular momentum of photons by combined computer-generated hologram （CCGH） fabricated in silica glass with femtosecond laser pulses. Firstly, the two computer-generated holograms （CGH） of optical vortex were obtained and combined as a CCGH according to the design. Then the CCGH was directly written inside glass by femtosecond laser pulses induced microexplosion without any preor post-treatment of the material. The vortex beams with different vortex topological charges （including new topological charges） have been restructured using a collimated He-Ne laser beam incidence to the CCGH normally. A theoretical and experimental explanation has been presented for the generations of the new topological charges.展开更多
The rotational motions of the optically trapped microscopic particles by the vortex femtosecond laser beam are investigated in this paper.Black particles can be trapped and rotated by a vortex femtosecond laser beam v...The rotational motions of the optically trapped microscopic particles by the vortex femtosecond laser beam are investigated in this paper.Black particles can be trapped and rotated by a vortex femtosecond laser beam very effectively because the vortex beam carries orbital angular momentum due to the helical wave-front structure in assoication with the central phase singularity.Trapped black particles rotate in the vortex beam due to the absorption of the angular momentum transferred from the vortex beam.The rotating directions of the trapped particles can be modulated by reversing the topological charge of the optical vortex in the vortex femtosecond beam.And the rotating speeds of the trapped microscopic particles greatly depend on the topological charges of the vortex tweezer and the used pulse energies.展开更多
This study describes the fabrication of ZnO-nanowire films by electro-chemical anodization of Zn foil. The ZnO films are characterized by field emission scanning electron microscopy, X-ray diffraction patterns, and tr...This study describes the fabrication of ZnO-nanowire films by electro-chemical anodization of Zn foil. The ZnO films are characterized by field emission scanning electron microscopy, X-ray diffraction patterns, and transmission electron microscopy, respectively. The ultraviolet （UV） photo-response properties of the surface-contacted ZnO film are studied through the current evolution processes under different relative humidities. Unlike the usually observed current spectra of the ZnO films, the drop time is shorter than the rise time. The photo-conductivity gain G and the response time T are both increased with the increase of the applied bias. The photo-conductivity gain G is lowered with the increase of the environmental humidity, while the response time τ- is increased. These results can be explained by considering three different surface processes： 1） the electron-hole （e-p） pair generation by the UV light illumination, 2） the following surface O2 species desorption, and 3） the photo-catalytic hydrolysis of water molecules adsorbed on the ZnO surface. The slow-rise and fast-drop current feature is suggested to originate from the sponge-like structure of the ZnO nanowires.展开更多
Detector has become an indispensable part of human beings.The increasing demand for photodetectors with high performance has promoted the research of novel materials.At the same time,with the development of rising mat...Detector has become an indispensable part of human beings.The increasing demand for photodetectors with high performance has promoted the research of novel materials.At the same time,with the development of rising material system,two-dimensional(2D)materials attract a lot of attention,while the suitable option for fabricating photodetector is still limited.The prospering of bismuth chalcogenides injected new vitality for material field,thereinto,the unique topological insulator characteristics make the research on bismuth selenide(Bi_(2)X_(3))and bismuth telluride(Bi_(2)X_(3)) intriguing.2D Bi_(2)X_(3) also exhibits unique features among various 2D materials,of which,the adjustable narrow energy band gap and polarization-sensitive photocurrent contribute to the promising application of high performance and broadband photodetector.In this review,from a bottom-up perspective,we summarize fundamental properties,synthesis method,photodetector performance of 2D Bi_(2)X_(3) based on the previous study,which provide an overall perspective of 2D Bi_(2)X_(3).Wherein,the section of the photodetector is specifically discu ssed with regard to pure Bi_(2)X_(3) photodetector and heterojunction photodetector.A brief summary and outlook were also explored in the end.展开更多
Ultrashort pulses complicate the frequency conversion in a nonlinear crystal, where group velocity mismatch becomes the main obstacle due to dispersion. We present a design for group velocity compensated second harmon...Ultrashort pulses complicate the frequency conversion in a nonlinear crystal, where group velocity mismatch becomes the main obstacle due to dispersion. We present a design for group velocity compensated second harmonic generation in a modulated nonlinear structure, embedded in a liquid crystal box. In this structure, nonlinear crystals act as sources of signal and liquid crystals compensate for group velocity mismatch originating from nonlinear crystals. There are the advantages of the flexible, controllable birefringence of liquid crystals. Meanwhile, a method calculating the parameters of this type of structure is presented. To make it clear, an example is provided. Furthermore, the structure can also be shaped as a waveguide to support integration into other optical devices, applicable to all-optical processing systems.展开更多
Raman spectroscopy is used to monitor hydrogenation of graphene on polydimethylsiloxane （PDMS） as well as on SiO2/Si substrates. It is found that hydrogenation of graphene on SiO2/Si is much more feasible than that ...Raman spectroscopy is used to monitor hydrogenation of graphene on polydimethylsiloxane （PDMS） as well as on SiO2/Si substrates. It is found that hydrogenation of graphene on SiO2/Si is much more feasible than that on PDMS. For graphene on PDMS substrates, hydrogenation of graphene is favored on very flexible substrates. The substrate （SiO2/Si and PDMS） and flexibility （PDMS with different flexibility） dependent hydrogenation behavior can be understood by different interactions between graphene and substrate. The interaction between graphene and SiO2/Si is relative weak （van der Waals force） and the interaction between graphene and PDMS is relative strong, where substrate induced prestrain in the graphene layer is observed. For graphene embedded on the PDMS substrate, the more flexible the substrate is, the weaker the interaction between PDMS and graphene. The understanding of the effect of PDMS＇s flexibility on hydrogenation of graphene will be helpful for graphene based flexible electronics.展开更多
Employing a simple and efficient method of electro-chemical anodization, ZnO nanowire films are fabricated on Zn foil, and an ultraviolet （UV） sensor prototype is formed for investigating the electronic transport th...Employing a simple and efficient method of electro-chemical anodization, ZnO nanowire films are fabricated on Zn foil, and an ultraviolet （UV） sensor prototype is formed for investigating the electronic transport through back-to-back double junctions. The UV （365 nm） responses of surface-contacted ZnO film are provided by I-V measurement, along with the current evolution process by on/off of UV illumination. In this paper, the back-to-back metal-seconductor-metal （M-S-M） model is used to explain the electronic transport of a ZnO nanowire film based structure. A thermionic-field electron emission mechanism is employed to fit and explain the as-observed UV sensitive electronic transport properties of ZnO film with surface-modulation by oxygen and water molecular coverage.展开更多
A formula was brought forward to correlate residual strain with hardness measured by nanoindentation method. Using the formula, residual strains in prestrained aluminum alloy samples were evaluated. In order to compar...A formula was brought forward to correlate residual strain with hardness measured by nanoindentation method. Using the formula, residual strains in prestrained aluminum alloy samples were evaluated. In order to compare with the calculated strain, such values were also measured by strain gauge method. The results show that the differences of the residual strain obtained by nanoindentation and strain gauge method are not more than 8%, which shows that the formula is suitable for characterizing residual strain of aluminum alloy.展开更多
Purpose–To address the encapsulation challenge of fiber Bragg grating(FBG)sensors in complex railway environments,this paper designs a clip-on composite sensor enabling installation-friendly deployment and long-term ...Purpose–To address the encapsulation challenge of fiber Bragg grating(FBG)sensors in complex railway environments,this paper designs a clip-on composite sensor enabling installation-friendly deployment and long-term axle counting system monitoring.Design/methodology/approach–Wheel–rail mechanical behavior was simulated via finite element analysis(FEA)to determine optimal sensor placement.A clip-on composite sensor was subsequently engineered.Stress transduction efficacy was validated through FEA quantification of stress responses at the axle counter location.Findings–The proposed FBG axle counter integrates temperature compensation and anti-detachment monitoring as well as advantages such as simplified installation with minimal maintenance and sustained operational reliability.It effectively transmits stress,yielding a measured strain of 39μe under static loading conditions without sensitivity-enhancing elements.Originality/value–This study performs FEA of wheel-rail stress distribution and engineers the dual-slot composite sensor,FEAwas conducted to quantify the stress magnitude at the axle sensor position of the dual-slot composite sensor.Additionally,FEA was performed on sensors with different structural configurations,including adjustments to the axle sensor position,number of slots and axle position.The results confirmed that the designed composite sensor exhibits superior stress transfer characteristics.展开更多
This paper investigates the generation of self-organized surface structures on amorphous alloys by vortex femtosecond laser pulses. The scanning electron microscope characterizations show that the as-formed structures...This paper investigates the generation of self-organized surface structures on amorphous alloys by vortex femtosecond laser pulses. The scanning electron microscope characterizations show that the as-formed structures are periodic ripples, aperiodic ripples, and ‘coral-like＇ structures. Optimal conditions for forming these surface structures are determined in terms of pulses number at a given pulse energy. The applicable mechanism is suggested to interpret the formation and evolution of the ＇coral-like＇ structures.展开更多
Metasurfaces that can realize the polarization manipulation of electromagnetic waves on the sub-wavelength scale have become an emerging research field.Here,a novel strategy of combining the metasurface and Fresnel zo...Metasurfaces that can realize the polarization manipulation of electromagnetic waves on the sub-wavelength scale have become an emerging research field.Here,a novel strategy of combining the metasurface and Fresnel zone plate to form a metasurface zone plate is proposed to realize the conversion from nearly arbitrary polarizations to a fixed polarization.Specifically,when one polarized wave is incident on adjacent ring zones constructed by different types of meta-atoms,the transmitted waves generated by odd-numbered and even-numbered ring zones converge at the same focus and superimpose to generate a fixed polarized wave.As function demonstrations,we have designed two types of metasurface zone plates:one is a focused linear polarizer,and the other can convert nearly arbitrary polarized waves into focused circularly polarized waves.The simulated and measured results are consistent with theoretical expectations,suggesting that the proposed concept is flexible and feasible.Our work provides an alternative platform for polarization manipulation and may vigorously promote the development of polarization photonic devices.展开更多
Supercontinuum generation and compression in a length of 50-ram photonic crystal fiber with pulse of nanojoule energy are investigated theoretically and experimentally. Chirped mirror pair is used for dispersion compe...Supercontinuum generation and compression in a length of 50-ram photonic crystal fiber with pulse of nanojoule energy are investigated theoretically and experimentally. Chirped mirror pair is used for dispersion compensation and pulse compression. Pulse characteristics are measured by frequency-resolved optical gating. And 19-fs pulse is generated.展开更多
Group velocity mismatch becomes the main obstacle for frequency conversion of ultrashort pulses due to dispersion. To solve the problem, one design is proposed for group velocity compensated second harmonic generation...Group velocity mismatch becomes the main obstacle for frequency conversion of ultrashort pulses due to dispersion. To solve the problem, one design is proposed for group velocity compensated second harmonic generation in a periodically modulated BBO crystal structure： the α-BBO/β-BBO multi-layer microstructure. The results show that the device can be well applied from the visible red to the near infrared region.展开更多
Phase-modulated metasurfaces that can implement the independent manipulation of co-and cross-polarized output waves under circularly polarized[CP]incidence have been proposed.With this,we introduce one particular meta...Phase-modulated metasurfaces that can implement the independent manipulation of co-and cross-polarized output waves under circularly polarized[CP]incidence have been proposed.With this,we introduce one particular metasurface composed of meta-atoms with a phase difference of 2π/3 to generate specific elliptically polarized waves under various polarized incidences.Furthermore,a metasurface composed of these above meta-atoms and the meta-atoms with a phase difference of π/3 arranged in a certain rule can realize polarization conversion function between linearly polarized and CP states.The designs shed new light on multifarious optical devices and may further promote the development of metasurface polarization optics.展开更多
Platinum telluride(PtTe_(2)),a member of metallic transition metal dichalcogenides,provides a new platform for investigating various properties such as type-II Dirac fermions,topological superconductivity,and wide-ban...Platinum telluride(PtTe_(2)),a member of metallic transition metal dichalcogenides,provides a new platform for investigating various properties such as type-II Dirac fermions,topological superconductivity,and wide-band photodetection.However,the study of PtTe_(2)is largely limited to exfoliated flakes,and its direct synthesis remains challenging.Herein,we report the controllable synthesis of highly crystalline 2D PtTe_(2)crystals with tunable morphology and thickness via chemical vapor deposition(CVD)growth on Au substrate.By adjusting Te amount and substrate temperature,anisotropic and isotropic growth modes of PtTe_(2)were realized on the solid and molten Au substrates,respectively.The domain size of PtTe_(2)crystal was achieved up to 30μm,and its thickness can be tuned from 5.6 to 50 nm via controlling the growth time.Furthermore,a metal–PtTe_(2)–metal structural device was fabricated to validate the wide-band terahertz(THz)photodetection from 0.04 to 0.3 THz at room temperature.Owing to the high crystallinity of PtTe_(2)crystal,the photodetector acquires high responsivity(30–250 mA W-1 from 0.12 to 0.3 THz),fast response rate(rise time:7μs,decay time:8μs),and high-quality imaging ability.Our work demonstrates the feasibility for realistic exploitation of high-performing photodetection system at THz band based on the CVDgrown 2D Dirac semimetal materials.展开更多
In this work,Raman measurements of 1-5-layer WSe2 supported on SiO2/Si in the temperature range of 133 to 533 K are reported.A physical model including both volume effect and temperature effect is used to quantitative...In this work,Raman measurements of 1-5-layer WSe2 supported on SiO2/Si in the temperature range of 133 to 533 K are reported.A physical model including both volume effect and temperature effect is used to quantitatively understand the nonlinear temperature dependence of E2g^1Raman mode.It is found this nonlinear dependence of Raman mode mainly originates from thermal expansion effect and three-phonon scattering.The former effect increases with an increase in number of layers,which is inverse for the latter effect.The temperature-dependent thermal expansion coefficients of 1-5-layer WSe2 are also obtained from Raman spectra.The full width at half maximum(FWHM)of E;g mode is also systematically studied both experimentally and theoretically in the temperature range of 133 to 413 K.It is found that the increase in FWHM of E2g^1 mode originates from decaying of E2g^1 phonon.This work will promote the understanding of anharmonic behaviors of phonons in WSe2 flakes with different thicknesses.展开更多
Flexible manipulation and efficient detection of terahertz wave polarization states remain critical challenges for advancing terahertz technologies in communications, biomedicine, and environmental monitoring. This st...Flexible manipulation and efficient detection of terahertz wave polarization states remain critical challenges for advancing terahertz technologies in communications, biomedicine, and environmental monitoring. This study innovatively proposes an all-dielectric metadevice integrated platform that achieves coordinated polarization generation and detection through multidimensional polarization-channel multiplexing. The proposed device integrates four polarization-conversion functional units into a single planar architecture, enabling synchronous generation of four independent polarization channels under unpolarized incidence while establishing direct correlations between their intensity profiles and the polarization state of incident waves. Leveraging the Stokes parameter framework, we develop a high-efficiency detection mechanism that precisely reconstructs incident polarization states utilizing only four-channel intensity information, overcoming the limitations of conventional multi-component cascaded polarization detection systems. Experimental results demonstrate the device's exceptional polarization-resolving capability at 0.9 THz. Furthermore, the platform exhibits significant potential for multidimensional optical field manipulation, successfully generating four-channel polarization-vortex beams with independent topological charges. This compact multichannel polarization-control strategy opens new avenues, to our knowledge, for developing portable terahertz imaging systems, high-capacity communication devices,and multidimensional information encryption technologies, thereby accelerating the practical implementation of terahertz science and applications.展开更多
作为一种多功能软填料,液态金属(LM)乳液为制备基于导电水凝胶的多功能应变传感器带来了新机遇.然而,界面张力和密度巨大的LM难以以稳定乳液的形式存在.本文中,我们展示了一种利用阳离子纤维素纳米纤维(CCNFs)包覆LM液滴来稳定LM乳液的...作为一种多功能软填料,液态金属(LM)乳液为制备基于导电水凝胶的多功能应变传感器带来了新机遇.然而,界面张力和密度巨大的LM难以以稳定乳液的形式存在.本文中,我们展示了一种利用阳离子纤维素纳米纤维(CCNFs)包覆LM液滴来稳定LM乳液的策略.通过将CCNF稳定的LM乳液与丙烯酸(AA)混合并引发其原位聚合,以及在聚丙烯酸(PAA)、LM液滴和CCNF之间形成可逆的氢键、离子配位键和静电交联,制备了一种导电水凝胶CCNF-LM-PAA.得益于PAA与CCNF之间形成的可逆氢键、离子配位键和静电结合作用,CCNF-LMPAA水凝胶具有良好的导电性(1.54 S m^(-1))、较高的拉伸强度和断裂伸长率、粘附性和快速自愈合能力.CCNF-LM-PAA水凝胶作为应变传感材料,具有超高应变灵敏度(应变系数高达16.2)、低应变检测极限(<1%)、短响应/恢复时间(107/91 ms)和良好的耐用性(300次循环).这些性能使得基于CCNF-LM-PAA水凝胶的应变传感器能够作为可穿戴电子器件用于监测各种人体活动.因此,利用CCNF稳定LM乳液引入静电结合作用,为提高基于LM乳液水凝胶的可穿戴电子器件的应变传感性能提供了一种实用的方法.展开更多
Despite the considerable effort,fast and highly sensitive photodetection is not widely available at the low-photon-energy range(~meV)of the electromagnetic spectrum,owing to the challenging light funneling into small ...Despite the considerable effort,fast and highly sensitive photodetection is not widely available at the low-photon-energy range(~meV)of the electromagnetic spectrum,owing to the challenging light funneling into small active areas with efficient conversion into an electrical signal.Here,we provide an alternative strategy by efficiently integrating and manipulating at the nanoscale the optoelectronic properties of topological Dirac semimetal PtSe_(2)and its van der Waals heterostructures.Explicitly,we realize strong plasmonic antenna coupling to semimetal states near the skin-depth regime(λ/10^(4)),featuring colossal photoresponse by in-plane symmetry breaking.The observed spontaneous and polarization-sensitive photocurrent are correlated to strong coupling with the nonequilibrium states in PtSe_(2)Dirac semimetal,yielding efficient light absorption in the photon range below 1.24 meV with responsivity exceeding∼0.2 A/W and noise-equivalent power(NEP)less than~38 pW/Hz^(0.5),as well as superb ambient stability.Present results pave the way to efficient engineering of a topological semimetal for high-speed and low-energy photon harvesting in areas such as biomedical imaging,remote sensing or security applications.展开更多
Topological insulators represent a new quantum phase of matter with spin-polarized surface states that are protected from backscattering, exhibiting electronic responses to light, such as topological quantum phase tra...Topological insulators represent a new quantum phase of matter with spin-polarized surface states that are protected from backscattering, exhibiting electronic responses to light, such as topological quantum phase transitions. However, the effects of high-frequency driving topological intrinsic systems have remained largely unexplored challenges experimentally for high-sensitivity terahertz detection. In this study, by integrating Sb2Te3 topological insulators with subwavelength metal antennas through micro-nano processing, a high-frequency terahertz detector with high sensitivity is proposed. The enhanced response originates from the asymmetric scattering of the surface electrons in the Sb_(2)Te_(3) flakes induced by the terahertz wave. The device displays room-temperature photodetection with a responsivity of 192 mA/W and equivalent noise power of less than 0.35 nW/Hz^(1/2) in the frequency range from 0.02 to 0.3 THz. These results pave the way for the exploitation of topological insulators for high-frequency operation in real-time imaging within long-wavelength optoelectronics.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10674038 and 10604042)National Basic Research Program of China (Grant No 2006CB302901)+1 种基金the Multidiscipline Scientific Research Foundation of Harbin Institute of Technology, China (Grant No HIT.MD2003.22)the Foundation of Harbin Institute of Technology at Weihai of China (Grant No HIT(WH).2005.20)
文摘This paper introduces a novel method to realize the superposition of orbital angular momentum of photons by combined computer-generated hologram （CCGH） fabricated in silica glass with femtosecond laser pulses. Firstly, the two computer-generated holograms （CGH） of optical vortex were obtained and combined as a CCGH according to the design. Then the CCGH was directly written inside glass by femtosecond laser pulses induced microexplosion without any preor post-treatment of the material. The vortex beams with different vortex topological charges （including new topological charges） have been restructured using a collimated He-Ne laser beam incidence to the CCGH normally. A theoretical and experimental explanation has been presented for the generations of the new topological charges.
基金Project supported by the National Natural Science Foundation for Post-Doctoral Scientists of China (Grant No. 2012M511002)the National Natural Science Foundation of China (Grant Nos. 10904027 and 61108018)the Science and Technology Programs of Heilongjiang Educational Committee,China (Grant No. 12511425)
文摘The rotational motions of the optically trapped microscopic particles by the vortex femtosecond laser beam are investigated in this paper.Black particles can be trapped and rotated by a vortex femtosecond laser beam very effectively because the vortex beam carries orbital angular momentum due to the helical wave-front structure in assoication with the central phase singularity.Trapped black particles rotate in the vortex beam due to the absorption of the angular momentum transferred from the vortex beam.The rotating directions of the trapped particles can be modulated by reversing the topological charge of the optical vortex in the vortex femtosecond beam.And the rotating speeds of the trapped microscopic particles greatly depend on the topological charges of the vortex tweezer and the used pulse energies.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60907023)the Shandong Excellent Young Scientist Research Award Fund Project,China (Grant No. BS2011CL002)+1 种基金the Natural Science Foundation of Heilongjiang Province,China (Grant No. A200912)the Science and Technology Progress Project of Weihai,China (Grant Nos. IMJQ01110003 and 20090393)
文摘This study describes the fabrication of ZnO-nanowire films by electro-chemical anodization of Zn foil. The ZnO films are characterized by field emission scanning electron microscopy, X-ray diffraction patterns, and transmission electron microscopy, respectively. The ultraviolet （UV） photo-response properties of the surface-contacted ZnO film are studied through the current evolution processes under different relative humidities. Unlike the usually observed current spectra of the ZnO films, the drop time is shorter than the rise time. The photo-conductivity gain G and the response time T are both increased with the increase of the applied bias. The photo-conductivity gain G is lowered with the increase of the environmental humidity, while the response time τ- is increased. These results can be explained by considering three different surface processes： 1） the electron-hole （e-p） pair generation by the UV light illumination, 2） the following surface O2 species desorption, and 3） the photo-catalytic hydrolysis of water molecules adsorbed on the ZnO surface. The slow-rise and fast-drop current feature is suggested to originate from the sponge-like structure of the ZnO nanowires.
基金financially supported by the National Key Research and Development Program of China(No.2019YFA0705201)Heilongjiang Touyan Team。
文摘Detector has become an indispensable part of human beings.The increasing demand for photodetectors with high performance has promoted the research of novel materials.At the same time,with the development of rising material system,two-dimensional(2D)materials attract a lot of attention,while the suitable option for fabricating photodetector is still limited.The prospering of bismuth chalcogenides injected new vitality for material field,thereinto,the unique topological insulator characteristics make the research on bismuth selenide(Bi_(2)X_(3))and bismuth telluride(Bi_(2)X_(3)) intriguing.2D Bi_(2)X_(3) also exhibits unique features among various 2D materials,of which,the adjustable narrow energy band gap and polarization-sensitive photocurrent contribute to the promising application of high performance and broadband photodetector.In this review,from a bottom-up perspective,we summarize fundamental properties,synthesis method,photodetector performance of 2D Bi_(2)X_(3) based on the previous study,which provide an overall perspective of 2D Bi_(2)X_(3).Wherein,the section of the photodetector is specifically discu ssed with regard to pure Bi_(2)X_(3) photodetector and heterojunction photodetector.A brief summary and outlook were also explored in the end.
基金Supported by the Natural Science Foundation of Heilongjiang Province under Grant Nos F201312,F2016023 and QC2015086the National Natural Science Foundation of China under Grant No 61405049
文摘Ultrashort pulses complicate the frequency conversion in a nonlinear crystal, where group velocity mismatch becomes the main obstacle due to dispersion. We present a design for group velocity compensated second harmonic generation in a modulated nonlinear structure, embedded in a liquid crystal box. In this structure, nonlinear crystals act as sources of signal and liquid crystals compensate for group velocity mismatch originating from nonlinear crystals. There are the advantages of the flexible, controllable birefringence of liquid crystals. Meanwhile, a method calculating the parameters of this type of structure is presented. To make it clear, an example is provided. Furthermore, the structure can also be shaped as a waveguide to support integration into other optical devices, applicable to all-optical processing systems.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11104047,61376104 and 11104026the Scientific Research Foundation for the Returned Overseas Chinese Scholars of the State Education Ministry
文摘Raman spectroscopy is used to monitor hydrogenation of graphene on polydimethylsiloxane （PDMS） as well as on SiO2/Si substrates. It is found that hydrogenation of graphene on SiO2/Si is much more feasible than that on PDMS. For graphene on PDMS substrates, hydrogenation of graphene is favored on very flexible substrates. The substrate （SiO2/Si and PDMS） and flexibility （PDMS with different flexibility） dependent hydrogenation behavior can be understood by different interactions between graphene and substrate. The interaction between graphene and SiO2/Si is relative weak （van der Waals force） and the interaction between graphene and PDMS is relative strong, where substrate induced prestrain in the graphene layer is observed. For graphene embedded on the PDMS substrate, the more flexible the substrate is, the weaker the interaction between PDMS and graphene. The understanding of the effect of PDMS＇s flexibility on hydrogenation of graphene will be helpful for graphene based flexible electronics.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11274082 and 51172194)the Excellent Young Scientist Research Award Fund of Shandong Province,China(Grant No.BS2011CL002)
文摘Employing a simple and efficient method of electro-chemical anodization, ZnO nanowire films are fabricated on Zn foil, and an ultraviolet （UV） sensor prototype is formed for investigating the electronic transport through back-to-back double junctions. The UV （365 nm） responses of surface-contacted ZnO film are provided by I-V measurement, along with the current evolution process by on/off of UV illumination. In this paper, the back-to-back metal-seconductor-metal （M-S-M） model is used to explain the electronic transport of a ZnO nanowire film based structure. A thermionic-field electron emission mechanism is employed to fit and explain the as-observed UV sensitive electronic transport properties of ZnO film with surface-modulation by oxygen and water molecular coverage.
基金Project(20080440876) supported by China Postdoctoral Science FoundationProject(HIT(WH)XB200805) supported by Science Foundation of Harbin Institute of Technology at Weihai
文摘A formula was brought forward to correlate residual strain with hardness measured by nanoindentation method. Using the formula, residual strains in prestrained aluminum alloy samples were evaluated. In order to compare with the calculated strain, such values were also measured by strain gauge method. The results show that the differences of the residual strain obtained by nanoindentation and strain gauge method are not more than 8%, which shows that the formula is suitable for characterizing residual strain of aluminum alloy.
文摘Purpose–To address the encapsulation challenge of fiber Bragg grating(FBG)sensors in complex railway environments,this paper designs a clip-on composite sensor enabling installation-friendly deployment and long-term axle counting system monitoring.Design/methodology/approach–Wheel–rail mechanical behavior was simulated via finite element analysis(FEA)to determine optimal sensor placement.A clip-on composite sensor was subsequently engineered.Stress transduction efficacy was validated through FEA quantification of stress responses at the axle counter location.Findings–The proposed FBG axle counter integrates temperature compensation and anti-detachment monitoring as well as advantages such as simplified installation with minimal maintenance and sustained operational reliability.It effectively transmits stress,yielding a measured strain of 39μe under static loading conditions without sensitivity-enhancing elements.Originality/value–This study performs FEA of wheel-rail stress distribution and engineers the dual-slot composite sensor,FEAwas conducted to quantify the stress magnitude at the axle sensor position of the dual-slot composite sensor.Additionally,FEA was performed on sensors with different structural configurations,including adjustments to the axle sensor position,number of slots and axle position.The results confirmed that the designed composite sensor exhibits superior stress transfer characteristics.
基金Project supported by the Science and Technology Key Program of Shandong Province,China (Grant No. 2008GG10004020)China Postdoctoral Science Foundation (Grant No. AUGA41001348)+1 种基金Heilongjiang Province Postdoctoral Science Foundation(Grant No. AUGA1100074)the Program of Excellent Team in the Harbin Institute of Technology,China
文摘This paper investigates the generation of self-organized surface structures on amorphous alloys by vortex femtosecond laser pulses. The scanning electron microscope characterizations show that the as-formed structures are periodic ripples, aperiodic ripples, and ‘coral-like＇ structures. Optimal conditions for forming these surface structures are determined in terms of pulses number at a given pulse energy. The applicable mechanism is suggested to interpret the formation and evolution of the ＇coral-like＇ structures.
文摘Metasurfaces that can realize the polarization manipulation of electromagnetic waves on the sub-wavelength scale have become an emerging research field.Here,a novel strategy of combining the metasurface and Fresnel zone plate to form a metasurface zone plate is proposed to realize the conversion from nearly arbitrary polarizations to a fixed polarization.Specifically,when one polarized wave is incident on adjacent ring zones constructed by different types of meta-atoms,the transmitted waves generated by odd-numbered and even-numbered ring zones converge at the same focus and superimpose to generate a fixed polarized wave.As function demonstrations,we have designed two types of metasurface zone plates:one is a focused linear polarizer,and the other can convert nearly arbitrary polarized waves into focused circularly polarized waves.The simulated and measured results are consistent with theoretical expectations,suggesting that the proposed concept is flexible and feasible.Our work provides an alternative platform for polarization manipulation and may vigorously promote the development of polarization photonic devices.
文摘Supercontinuum generation and compression in a length of 50-ram photonic crystal fiber with pulse of nanojoule energy are investigated theoretically and experimentally. Chirped mirror pair is used for dispersion compensation and pulse compression. Pulse characteristics are measured by frequency-resolved optical gating. And 19-fs pulse is generated.
文摘Group velocity mismatch becomes the main obstacle for frequency conversion of ultrashort pulses due to dispersion. To solve the problem, one design is proposed for group velocity compensated second harmonic generation in a periodically modulated BBO crystal structure： the α-BBO/β-BBO multi-layer microstructure. The results show that the device can be well applied from the visible red to the near infrared region.
基金This work was supported by the National Natural Science Foundation of China(Nos.61675147,61735010,and 91838301)National Key Research and Development Program of China(No.2017YFA0700202).
文摘Phase-modulated metasurfaces that can implement the independent manipulation of co-and cross-polarized output waves under circularly polarized[CP]incidence have been proposed.With this,we introduce one particular metasurface composed of meta-atoms with a phase difference of 2π/3 to generate specific elliptically polarized waves under various polarized incidences.Furthermore,a metasurface composed of these above meta-atoms and the meta-atoms with a phase difference of π/3 arranged in a certain rule can realize polarization conversion function between linearly polarized and CP states.The designs shed new light on multifarious optical devices and may further promote the development of metasurface polarization optics.
基金Science and Technology Program of Shaanxi Province,Grant/Award Number:2017KJXX-16Natural Science Basic。
文摘Platinum telluride(PtTe_(2)),a member of metallic transition metal dichalcogenides,provides a new platform for investigating various properties such as type-II Dirac fermions,topological superconductivity,and wide-band photodetection.However,the study of PtTe_(2)is largely limited to exfoliated flakes,and its direct synthesis remains challenging.Herein,we report the controllable synthesis of highly crystalline 2D PtTe_(2)crystals with tunable morphology and thickness via chemical vapor deposition(CVD)growth on Au substrate.By adjusting Te amount and substrate temperature,anisotropic and isotropic growth modes of PtTe_(2)were realized on the solid and molten Au substrates,respectively.The domain size of PtTe_(2)crystal was achieved up to 30μm,and its thickness can be tuned from 5.6 to 50 nm via controlling the growth time.Furthermore,a metal–PtTe_(2)–metal structural device was fabricated to validate the wide-band terahertz(THz)photodetection from 0.04 to 0.3 THz at room temperature.Owing to the high crystallinity of PtTe_(2)crystal,the photodetector acquires high responsivity(30–250 mA W-1 from 0.12 to 0.3 THz),fast response rate(rise time:7μs,decay time:8μs),and high-quality imaging ability.Our work demonstrates the feasibility for realistic exploitation of high-performing photodetection system at THz band based on the CVDgrown 2D Dirac semimetal materials.
基金This work was supported the National Key R&D Program of China(Nos.2017YFF0108900,2016YFF0203802,and 2017YFD080120203)the Dalian Youth Science and Technology Star Project(No.2017RQ138)+2 种基金the project from Liaoning Education Department(No.JDL2019015)the National Natural Science Foundation of China(Nos.51872058 and 21904029)the Fundamental Research Funds for Central Universities(No.HIT.NSRIF 2019071).
文摘In this work,Raman measurements of 1-5-layer WSe2 supported on SiO2/Si in the temperature range of 133 to 533 K are reported.A physical model including both volume effect and temperature effect is used to quantitatively understand the nonlinear temperature dependence of E2g^1Raman mode.It is found this nonlinear dependence of Raman mode mainly originates from thermal expansion effect and three-phonon scattering.The former effect increases with an increase in number of layers,which is inverse for the latter effect.The temperature-dependent thermal expansion coefficients of 1-5-layer WSe2 are also obtained from Raman spectra.The full width at half maximum(FWHM)of E;g mode is also systematically studied both experimentally and theoretically in the temperature range of 133 to 413 K.It is found that the increase in FWHM of E2g^1 mode originates from decaying of E2g^1 phonon.This work will promote the understanding of anharmonic behaviors of phonons in WSe2 flakes with different thicknesses.
基金High-Level Talent Fund of Jiangsu University(JDKQ20250401)Sichuan Science and Technology Program(2025ZNSFSC0847)+1 种基金China Postdoctoral Science Foundation(2023TQ0296)Postdoctoral Fellowship Program of CPSF(GZC20232389).
文摘Flexible manipulation and efficient detection of terahertz wave polarization states remain critical challenges for advancing terahertz technologies in communications, biomedicine, and environmental monitoring. This study innovatively proposes an all-dielectric metadevice integrated platform that achieves coordinated polarization generation and detection through multidimensional polarization-channel multiplexing. The proposed device integrates four polarization-conversion functional units into a single planar architecture, enabling synchronous generation of four independent polarization channels under unpolarized incidence while establishing direct correlations between their intensity profiles and the polarization state of incident waves. Leveraging the Stokes parameter framework, we develop a high-efficiency detection mechanism that precisely reconstructs incident polarization states utilizing only four-channel intensity information, overcoming the limitations of conventional multi-component cascaded polarization detection systems. Experimental results demonstrate the device's exceptional polarization-resolving capability at 0.9 THz. Furthermore, the platform exhibits significant potential for multidimensional optical field manipulation, successfully generating four-channel polarization-vortex beams with independent topological charges. This compact multichannel polarization-control strategy opens new avenues, to our knowledge, for developing portable terahertz imaging systems, high-capacity communication devices,and multidimensional information encryption technologies, thereby accelerating the practical implementation of terahertz science and applications.
基金supported by the National Natural Science Foundation of China(52172147 and 22006082)the Natural Science Foundation of Shandong Province(ZR2021MC034,ZR2021MB035,and ZR2020MB128)Shandong Province Key Research and Development Program(2021ZDSYS18)。
文摘作为一种多功能软填料,液态金属(LM)乳液为制备基于导电水凝胶的多功能应变传感器带来了新机遇.然而,界面张力和密度巨大的LM难以以稳定乳液的形式存在.本文中,我们展示了一种利用阳离子纤维素纳米纤维(CCNFs)包覆LM液滴来稳定LM乳液的策略.通过将CCNF稳定的LM乳液与丙烯酸(AA)混合并引发其原位聚合,以及在聚丙烯酸(PAA)、LM液滴和CCNF之间形成可逆的氢键、离子配位键和静电交联,制备了一种导电水凝胶CCNF-LM-PAA.得益于PAA与CCNF之间形成的可逆氢键、离子配位键和静电结合作用,CCNF-LMPAA水凝胶具有良好的导电性(1.54 S m^(-1))、较高的拉伸强度和断裂伸长率、粘附性和快速自愈合能力.CCNF-LM-PAA水凝胶作为应变传感材料,具有超高应变灵敏度(应变系数高达16.2)、低应变检测极限(<1%)、短响应/恢复时间(107/91 ms)和良好的耐用性(300次循环).这些性能使得基于CCNF-LM-PAA水凝胶的应变传感器能够作为可穿戴电子器件用于监测各种人体活动.因此,利用CCNF稳定LM乳液引入静电结合作用,为提高基于LM乳液水凝胶的可穿戴电子器件的应变传感性能提供了一种实用的方法.
基金This work was supported by the National Key R&D Program of China(No.2021YFB2800702)the National Natural Science Foundation of China(Nos.61521005,61875217,91850208)+4 种基金the STCSM Grants(Nos.1859078100,19590780100)The project was funded by State Key Laboratory for Modification of Chemical Fibers and Polymer Materials,Donghua University(KF1809)Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)Zhejiang Lab(No.2021MB0AB01)the Natural Science Foundation of Shanghai(No.21ZR1402200).
文摘Despite the considerable effort,fast and highly sensitive photodetection is not widely available at the low-photon-energy range(~meV)of the electromagnetic spectrum,owing to the challenging light funneling into small active areas with efficient conversion into an electrical signal.Here,we provide an alternative strategy by efficiently integrating and manipulating at the nanoscale the optoelectronic properties of topological Dirac semimetal PtSe_(2)and its van der Waals heterostructures.Explicitly,we realize strong plasmonic antenna coupling to semimetal states near the skin-depth regime(λ/10^(4)),featuring colossal photoresponse by in-plane symmetry breaking.The observed spontaneous and polarization-sensitive photocurrent are correlated to strong coupling with the nonequilibrium states in PtSe_(2)Dirac semimetal,yielding efficient light absorption in the photon range below 1.24 meV with responsivity exceeding∼0.2 A/W and noise-equivalent power(NEP)less than~38 pW/Hz^(0.5),as well as superb ambient stability.Present results pave the way to efficient engineering of a topological semimetal for high-speed and low-energy photon harvesting in areas such as biomedical imaging,remote sensing or security applications.
基金Shanghai Municipal Science and Technology Major Project(2019SHZDZX01)Science and Technology Commission of Shanghai Municipality(20JC1416000,20QA1410400,22JC1402900)+3 种基金Excellent Postdoctoral Research Projects of Zhejiang Province(ZJ2021019)Natural Science Foundation of Zhejiang Province(LQ20F050005,LR22F050004)National Natural Science Foundation of China(62222514,61521005,61875217,61875218,61875223,61991442,62005249,91850208)State Key Program for Basic Research of China(2018YFA0306200).
文摘Topological insulators represent a new quantum phase of matter with spin-polarized surface states that are protected from backscattering, exhibiting electronic responses to light, such as topological quantum phase transitions. However, the effects of high-frequency driving topological intrinsic systems have remained largely unexplored challenges experimentally for high-sensitivity terahertz detection. In this study, by integrating Sb2Te3 topological insulators with subwavelength metal antennas through micro-nano processing, a high-frequency terahertz detector with high sensitivity is proposed. The enhanced response originates from the asymmetric scattering of the surface electrons in the Sb_(2)Te_(3) flakes induced by the terahertz wave. The device displays room-temperature photodetection with a responsivity of 192 mA/W and equivalent noise power of less than 0.35 nW/Hz^(1/2) in the frequency range from 0.02 to 0.3 THz. These results pave the way for the exploitation of topological insulators for high-frequency operation in real-time imaging within long-wavelength optoelectronics.
