A star hybrid inorganic-organic perovskite material selected as an outstanding absorbing layer in solar cells benefits from multiple preparation techniques and excellent photoelectric characteristics. Among numerous s...A star hybrid inorganic-organic perovskite material selected as an outstanding absorbing layer in solar cells benefits from multiple preparation techniques and excellent photoelectric characteristics. Among numerous synthetic processes, uniform, compact, and multi-stack perovskite thin films can be manufactured using vacuum deposition. During sequential vacuum deposition, the penetration ability of the organic molecules cannot be effectively controlled. In addition, the rela- tionship between the thickness of the inorganic seeding layer and the organic molecule concentration for optimized devices using an evaporation-solution method is unclear. In this work, we prepared high-quality perovskite films by effectively con- trolling the penetration ability and chemical quantity of organic methyl ammonium iodide by monitoring the evaporation pressure and time. Thus, a device efficiency of over 15% was achieved with an all-vacuum prepared perovskite film. For the evaporation-solution method, we reacted different thicknesses of inorganic lead iodine with various concentrations of the organic molecule solution. The inorganic layer thickness and organic molecule concentration showed a linear relationship to achieve an optimum perovskite film, and an empirical formula was obtained. This work noted the key parameters of two intercalation reactions to prepare perovskite films, which paves a way to deliver a device that enables multi-layered structures, such as tandem solar cells.展开更多
Cylindrical vector beams(CVBs)hold significant promise in mode division multiplexing communication owing to their inherent vector mode orthogonality.However,existing studies for facilitating CVB channel processing are...Cylindrical vector beams(CVBs)hold significant promise in mode division multiplexing communication owing to their inherent vector mode orthogonality.However,existing studies for facilitating CVB channel processing are confined to mode shift conversions due to their reliance on spin-dependent helical modulations,overlooking the pursuit of mode multiplication conversion.This challenge lies in the multiplicative operation upon inhomogeneous vector mode manipulation,which is expected to advance versatile CVB channel switching and routing.Here,we tackle this gap by introducing a raytracing control strategy that conformally maps the light rays of CVB from the whole annulus distribution to an annular sector counterpart.Incorporated with the multifold conformal annulus-sector mappings and polarization-insensitive phase modulations,this approach facilitates the parallel transformation of input CVB into multiple complementary components,enabling the mode multiplication conversion with protected vector structure.Serving as a demonstration,we experimentally implemented the multiplicative operation of four CVB modes with the multiplier factors of N=+2 and N=−3,achieving the converted mode purities over 94.24%and 88.37%.Subsequently,200 Gbit/s quadrature phase shift keying signals were successfully transmitted upon multiplicative switching of four CVB channels,with the bit-error-rate approaching 1×10^(−6).These results underscore our strategy’s efficacy in CVB mode multiplication,which may open promising prospects for its advanced applications.展开更多
In this work, we review the developing progress of two-dimensional terahertz time-domain spectroscopy（THz-TDS） and its diverse applications, including analyzing the polarization of THz radiation from a laser-induced...In this work, we review the developing progress of two-dimensional terahertz time-domain spectroscopy（THz-TDS） and its diverse applications, including analyzing the polarization of THz radiation from a laser-induced plasma source and studying the corresponding physical mechanism, and characterizing the optical properties of crystals, etc.展开更多
The optimization of the fiber-coupled terahertz time-domain spectroscopy（THz-TDS） system is performed by changing the polarization of the optical excitation pulse centered at 1550 nm. In Ga As/In Al As multilayer st...The optimization of the fiber-coupled terahertz time-domain spectroscopy（THz-TDS） system is performed by changing the polarization of the optical excitation pulse centered at 1550 nm. In Ga As/In Al As multilayer structures based photoconductive antennas are used in TDS setup as both the emitter and receiver. The experimental results demonstrate that not only the THz signal power but also the temporal waveform vary with the rotation of the exciting pulse polarization. Maximum output power of the emitter is obtained when the polarization of the pump pulse is perpendicular to the edge of the metal electrodes. At this moment the THz waveform is close to a single-cycled pulse. However, double THz pulses could be recorded when the pump laser polarization is parallel to the electrodes. Laser pulse splitting induced by the birefringence of the optical fiber may attribute to the polarizationdependent performance of the fiber-coupled THz-TDS system.展开更多
A series of In Sb thin films were grown on Ga As substrates by molecular beam epitaxy(MBE).Ga Sb/Al In Sb is used as a compound buffer layer to release the strain caused by the lattice mismatch between the substrate a...A series of In Sb thin films were grown on Ga As substrates by molecular beam epitaxy(MBE).Ga Sb/Al In Sb is used as a compound buffer layer to release the strain caused by the lattice mismatch between the substrate and the epitaxial layer,so as to reduce the system defects.At the same time,the influence of different interface structures of Al In Sb on the surface morphology of buffer layer is explored.The propagation mechanism of defects with the growth of buffer layer is compared and analyzed.The relationship between the quality of In Sb thin films and the structure of buffer layer is summarized.Finally,the growth of high quality In Sb thin films is realized.展开更多
A new polarization rotator based on the silica photonic crystal fiber is proposed. The proposed polarization rotator photonic crystal fiber （PR-PCF） possesses a triangle jigsaw-shape core region. The full-vector fin...A new polarization rotator based on the silica photonic crystal fiber is proposed. The proposed polarization rotator photonic crystal fiber （PR-PCF） possesses a triangle jigsaw-shape core region. The full-vector finite-element method is used to analyze the phenomenon of polarization conversion between the quasi-TE and quasi-TM modes. Numerical simulations show that the wavelengths of 1.31 μm and 1.55 μm are converted with a nearly 100% polarization conversion ratio with their matched coupling length and has a relatively strong realistic fabrication tolerance - 100 nm on the y axis and 50 nm on the x axis. The full vectorial finite difference beam propagation method is used to confirm the performance of the proposed PR-PCF.展开更多
A new approach is presented to reveal the temporal structure of femtosecond laser pulses by recording the correspond- ing time-resolved shadowgraphs of the laser-induced air plasma. It is shown that the temporal struc...A new approach is presented to reveal the temporal structure of femtosecond laser pulses by recording the correspond- ing time-resolved shadowgraphs of the laser-induced air plasma. It is shown that the temporal structures of femtosecond laser pulses, normally not observable by the ordinary intensity autocorrelator, can be detected through intuitively analyz- ing the ultrafast evolution process of the air plasma induced by the femtosecond laser pulses under examination. With this method, existence of pre- and post-pulses has been clearly unveiled within the time window of 4-150 fs in reference with the main 50-fs laser pulses output from a commercial 1-kHz femtosecond laser amplifier. The unique advantage of the proposed method is that it can directly provide valuable information about the pulse temporal structures＇ effect on the laser-induced ionization or material ablation.展开更多
Digital holography can be applied to ultrafast detection when a femtosecond laser pulse is used. In this paper, the interference process of two femtosecond laser pulses is studied and the recording process of the femt...Digital holography can be applied to ultrafast detection when a femtosecond laser pulse is used. In this paper, the interference process of two femtosecond laser pulses is studied and the recording process of the femtosecond laser pulsed digital hologram is simulated. Holograms at different recording angles are generated by integrating the instantaneous interference field. By analyzing the distribution of the reconstructed phase error, the characteristics of femtosecond laser pulsed digital holography are discussed.展开更多
We demonstrate a photonic crystal cavity with a tapered waveguide and a point defect to highly confine terahertz waves.The terahertz wave is first guided into the tapered waveguide,gradually compressed to its end,and ...We demonstrate a photonic crystal cavity with a tapered waveguide and a point defect to highly confine terahertz waves.The terahertz wave is first guided into the tapered waveguide,gradually compressed to its end,and finally confined in the point defect cavity.Numerical simulations with the finite-difference time-domain method indicate that the narrow band terahertz wave is highly confined in the point defect cavity with a quality factor of 5323.The demonstrated device may be used as an antenna for enhancing light-matter interactions in the point defect cavity at terahertz frequencies and may improve the sensitivity of terahertz near-field microscopy.展开更多
We present a method of both polarization and amplitude modulations on an incident beam to obtain a longitudinally polarized subwavelength-sized optical needle. A 4-f system with a spatial light modulator is used to ge...We present a method of both polarization and amplitude modulations on an incident beam to obtain a longitudinally polarized subwavelength-sized optical needle. A 4-f system with a spatial light modulator is used to generate experimentally a two-mode alternate cylindrical vector beam by polarization modulation, enhancing performance and facilitating implementation. We optimize the beam focusing properties after passing the beam through an annular aperture to obtain amplitude modulation by the simulated annealing algorithm. Numerical results indicate that a sharp focal spot （0.417A） with a long focal depth （8A） and a strong longitudinally polarized field can be easily achieved.展开更多
The controlled growth of perovskite nanowires along predefined orientations offers significant advantages over traditional post-growth assembly strategies,facilitating their integration into compact functional devices...The controlled growth of perovskite nanowires along predefined orientations offers significant advantages over traditional post-growth assembly strategies,facilitating their integration into compact functional devices.In this study,a nanogroove-confined recrystallization process is designed for the precise and scalable growth of oriented perovskite nanowires with millimeter lengths and high crystallinity.The process involves annealing a perovskite-containing solution sandwiched between a hydrophobic flat silicon wafer and a hydrophilic faceted sapphire wafer featuring parallel nanogrooves at 90℃under ambient conditions.By customizing the electrode design,the nanowire arrays can be seamlessly integrated into monolithic photodetectors with large detection areas or into photodetector arrays with multiple microscale detector cells on their growth substrate.This in-situ integration strategy eliminates the need for complex post-growth processing steps.The photodetectors exhibit exceptional responsivity(38.4 A·W^(−1)),detectivity(4.35×10^(13)Jones),and response times in tens of microseconds across the ultraviolet-visible-near infrared ray(UV-vis-NIR)spectrum.The seamless integration of the nanowire photodetectors opens avenues for practical applications,including high-contrast optical imaging and efficient data transmission through Morse code encoding,leveraging their high on-off current ratios and rapid response.This innovative approach streamlines the growth of highly oriented perovskite nanowires,facilitating their integration into compact optoelectronic devices.展开更多
The terahertz region is a special region of the electromagnetic spectrum that incorporates the advantages of both microwaves and infrared light waves.In the past decade,metamaterials with effective medium parameters o...The terahertz region is a special region of the electromagnetic spectrum that incorporates the advantages of both microwaves and infrared light waves.In the past decade,metamaterials with effective medium parameters or gradient phases have been studied to control terahertz waves and realize functional devices.Here,we present a new approach to manipulate terahertz waves by using coding metasurfaces that are composed of digital coding elements.We propose a general coding unit based on a Minkowski closed-loop particle that is capable of generating 1-bit coding(with two phase states of 0 and 180°),2-bit coding(with four phase states of 0,90°,180°,and 270°),and multi-bit coding elements in the terahertz frequencies by using different geometric scales.We show that multi-bit coding metasurfaces have strong abilities to control terahertz waves by designing-specific coding sequences.As an application,we demonstrate a new scattering strategy of terahertz waves—broadband and wide-angle diffusion—using a 2-bit coding metasurface with a special coding design and verify it by both numerical simulations and experiments.The presented method opens a new route to reducing the scattering of terahertz waves.展开更多
In this work, it has been demonstrated that in order to fully understand the terahertz(THz) pulse generation process during femtosecond laser filamentation, the interaction between THz wave and air plasma has to be ta...In this work, it has been demonstrated that in order to fully understand the terahertz(THz) pulse generation process during femtosecond laser filamentation, the interaction between THz wave and air plasma has to be taken into account. This interaction is mainly associated with the spatial confinement of the THz pulse by the plasma column, which could be described by the one-dimensional negative dielectric(1DND) waveguide model. By combining the 1 DND model with the conventional four-wave mixing(4WM) and photocurrent(PC) models,the variation of THz spectral amplitude and width obtained in experiments could be better understood. Finally, a three-step procedure, with 1DND bridging 4WM and PC processes, has been established for the first time to describe the underlying mechanism of THz radiation from plasma sources.展开更多
Ammonia borane(NH_(3)BH_(3),AB) is promising for chemical hydrogen sto rage;however,current systems for rapid hydrogen production are limited by the expensive noble metal catalysts required for AB hydrolysis.Here we r...Ammonia borane(NH_(3)BH_(3),AB) is promising for chemical hydrogen sto rage;however,current systems for rapid hydrogen production are limited by the expensive noble metal catalysts required for AB hydrolysis.Here we report the design and synthesis of a highly efficient and robust non-noble-metal catalyst for the hydrolysis of AB at 298 K(TOF=89.56 molH_(2) min^(-1) molCo^(-1)).Experiments and density functional theory calculations were performed to explore the catalyst’s hybrid nanoparticle heterostructure and its catalytic mechanism.The catalyst comprised nitrogen-doped carbon dots confining CoO and CoP,and exhibited strong interface-induced synergistic catalysis for AB hydrolysis that effectively decreased the energy barriers for the dissociation of both AB and water molecules.The co-doping of N and P introduced numerous defects,and further regulated the reactivity of the carbon layers.The heterogeneous interface design technique presented here provides a new strategy for developing efficient and inexpensive non-noblemetal catalysts that may be applicable in other fields related to energy catalysis.展开更多
The laser scribing of polyimide(PI, Kapton) film is a new, simple and effective method for graphene preparation. Moreover,the superhydrophobic surface modification can undoubtedly widen the application fields of graph...The laser scribing of polyimide(PI, Kapton) film is a new, simple and effective method for graphene preparation. Moreover,the superhydrophobic surface modification can undoubtedly widen the application fields of graphene. Herein, inspired by the hydrophobic and self-cleaning properties of natural Oxalis corniculata Linn. leaves, we propose a novel bionic manufacturing method for superhydrophobic laser-induced graphene(LIG). By tailoring the geometric parameters(size, roughness and height/area ratio) and chemical composition, the three-dimensional(3D) multistage LIG, i.e., with micro-jigsaw-like and porous structure, can deliver a static water contact angle(WCA) of 153.5° ± 0.6°, a water sliding angle(WSA) of 2.5° ±0.5°, and great superhydrophobic stability lasting for 100 days(WCAs ≈ 150°). This outstanding water repellency is achieved by the secondary structure of jigsaw-like LIG, a porous morphology that traps air layers at the solid–liquid interface. The robust self-cleaning and anti-stick functions of 3D bionic and multistage LIG are demonstrated to confirm its great potential in wearable electronics.展开更多
Femtosecond （fs） pulse laser ablation of silicon targets in air and in vacuum is investigated using a timeresolved shadowgraphic method. The observed dynamic process of the fs laser ablation of silicon in air is sig...Femtosecond （fs） pulse laser ablation of silicon targets in air and in vacuum is investigated using a timeresolved shadowgraphic method. The observed dynamic process of the fs laser ablation of silicon in air is significantly different from that in vacuum. Similar to the ablation of metallic targets, while the shock wave front and a series of nearly concentric and semicircular stripes, as well as the contact front, are clearly identifiable in the process of ablation under 1 ×10^5 Pa, these phenomena are no longer observed when the ablation takes place in vacuum. Although the ambient air around the target strongly affects the evolution of the ablation plume, the three rounds of material ejection clearly observed in the shadowgraphs of fs laser ablation in standard air can also be distinguished in the process of ablation in vacuum. It is proven that the three rounds of material ejection are caused by different ablation mechanisms.展开更多
Multi-lane integrated transmitter chips are key components in future compact optical modules to realize high-speed optical interconnects.Thin-film lithium niobate(TFLN)photonics have emerged as a promising platform fo...Multi-lane integrated transmitter chips are key components in future compact optical modules to realize high-speed optical interconnects.Thin-film lithium niobate(TFLN)photonics have emerged as a promising platform for achieving high-performance chip-scale optical systems.Combining a coarse wavelength-division multiplexing(CWDM)devices using fabrication-tolerant angled multimode interferometer structure and high-performance electro-optical modulators,we demonstrate monolithic on-chip four-channel CWDM transmitter on the TFLN platform for the first time.The four-channel CWDM transmitter enables high-speed transmissions of 100 Gb/s data rate per wavelength channel(i.e.,an aggregated date rate of 400 Gb/s).展开更多
The plasmonic nanogap antenna is an efficient radiating or receiving optical device. The resonance behavior of optical antennas is commonly attributed to the excitation of a localized surface plasmon resonance(LSPR), ...The plasmonic nanogap antenna is an efficient radiating or receiving optical device. The resonance behavior of optical antennas is commonly attributed to the excitation of a localized surface plasmon resonance(LSPR), which can be theoretically defined as the quasi-normal mode(QNM). To clarify the physical origin of the LSPR, we build up an analytical model of the LSPR by considering a multiple scattering process of propagative surface plasmon polaritons(SPPs) on the antenna arms. The model can comprehensively reproduce the complex eigenfrequency and the field distribution of QNMs of the antenna, unveiling that the LSPR arises from a Fabry–Perot resonance of SPPs. By further applying the complex pole expansion theorem of meromorphic functions, the field of the antenna under illumination by a nearby dipole emitter can be analytically expanded with QNMs, which well predicts the frequency response of the enhancement factor of radiation. The present model establishes explicit relations between the concepts of the LSPR and the propagative SPP and integrates the advantages of the Fabry–Perot and QNM formalisms of nanogap antennas.展开更多
Passively mode-locked fiber lasers （PMLFLs） could be not only used as simple and economic ultrashort pulse sources but also as an ideal platform for exploring the nonlinear dynamics of dissipative solitons such as b...Passively mode-locked fiber lasers （PMLFLs） could be not only used as simple and economic ultrashort pulse sources but also as an ideal platform for exploring the nonlinear dynamics of dissipative solitons such as bound solitons, soliton rains, noise-like pulses, sideband-controllable solitons, soliton resonance,展开更多
Skyrmions are nano-scale quasi-particles with topological protection,which have potential applications in next-generation spintronics-based information storage.Numerous papers have been published to review various asp...Skyrmions are nano-scale quasi-particles with topological protection,which have potential applications in next-generation spintronics-based information storage.Numerous papers have been published to review various aspects of skyrmions,including physics,materials and applications.However,no review paper has focused on rare metals which play important roles in nucleating and manipulating skyrmions and other topological states.In this paper,various roles of rare metals have been classified and summarized,which can tune Curie temperature(TC),Dzyaloshinskii-Moriya interaction(DMI),magnetocrystalline anisotropy,Ruderman-Kittel-Kasuya-Yosida(RKKY)interaction and four-spin interaction so as to trigger the generation of skyrmions and other topological spin structures.The materials covered include typical B20 crystals,various layered systems with interfacial DMI,frustrated materials,antiferromagnets,ferrimagnets,twodimensional(2D)materials,etc.In addition,the rare-earth(RE)permanent magnets can provide an energy barrier and enrich the dynamic behaviors of skyrmions,which has also been reviewed.展开更多
基金Project supported by the International Cooperation Project of the Ministry of Science and Technology,China(Grant No.2014DFE60170)the National Natural Science Foundation of China(Grant Nos.61474065 and 61674084)+2 种基金Tianjin Research Key Program of Application Foundation and Advanced Technology,China(Grant No.15JCZDJC31300)Key Project in the Science&Technology Pillar Program of Jiangsu Province,China(Grant No.BE2014147-3)the 111 Project,China(Grant No.B16027)
文摘A star hybrid inorganic-organic perovskite material selected as an outstanding absorbing layer in solar cells benefits from multiple preparation techniques and excellent photoelectric characteristics. Among numerous synthetic processes, uniform, compact, and multi-stack perovskite thin films can be manufactured using vacuum deposition. During sequential vacuum deposition, the penetration ability of the organic molecules cannot be effectively controlled. In addition, the rela- tionship between the thickness of the inorganic seeding layer and the organic molecule concentration for optimized devices using an evaporation-solution method is unclear. In this work, we prepared high-quality perovskite films by effectively con- trolling the penetration ability and chemical quantity of organic methyl ammonium iodide by monitoring the evaporation pressure and time. Thus, a device efficiency of over 15% was achieved with an all-vacuum prepared perovskite film. For the evaporation-solution method, we reacted different thicknesses of inorganic lead iodine with various concentrations of the organic molecule solution. The inorganic layer thickness and organic molecule concentration showed a linear relationship to achieve an optimum perovskite film, and an empirical formula was obtained. This work noted the key parameters of two intercalation reactions to prepare perovskite films, which paves a way to deliver a device that enables multi-layered structures, such as tandem solar cells.
基金supported by the National Natural Science Foundation of China(Grant No.62271322)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2023A1515030152)+1 种基金the Shenzhen Science and Technology Program(Grant No.JCYJ20210324095610027)the Natural Science Foundation of Top Talent of SZTU(Grant No.GDRC202204)。
文摘Cylindrical vector beams(CVBs)hold significant promise in mode division multiplexing communication owing to their inherent vector mode orthogonality.However,existing studies for facilitating CVB channel processing are confined to mode shift conversions due to their reliance on spin-dependent helical modulations,overlooking the pursuit of mode multiplication conversion.This challenge lies in the multiplicative operation upon inhomogeneous vector mode manipulation,which is expected to advance versatile CVB channel switching and routing.Here,we tackle this gap by introducing a raytracing control strategy that conformally maps the light rays of CVB from the whole annulus distribution to an annular sector counterpart.Incorporated with the multifold conformal annulus-sector mappings and polarization-insensitive phase modulations,this approach facilitates the parallel transformation of input CVB into multiple complementary components,enabling the mode multiplication conversion with protected vector structure.Serving as a demonstration,we experimentally implemented the multiplicative operation of four CVB modes with the multiplier factors of N=+2 and N=−3,achieving the converted mode purities over 94.24%and 88.37%.Subsequently,200 Gbit/s quadrature phase shift keying signals were successfully transmitted upon multiplicative switching of four CVB channels,with the bit-error-rate approaching 1×10^(−6).These results underscore our strategy’s efficacy in CVB mode multiplication,which may open promising prospects for its advanced applications.
基金supported by the National Basic Research Program of China under Grant No.2014CB339802,No.2011CB808100the National Natural Science Foundation of China under Grant No.11174156
文摘In this work, we review the developing progress of two-dimensional terahertz time-domain spectroscopy（THz-TDS） and its diverse applications, including analyzing the polarization of THz radiation from a laser-induced plasma source and studying the corresponding physical mechanism, and characterizing the optical properties of crystals, etc.
基金supported by National Basic Research Program of China under Grant No.2014CB339802,No.2011CB808100National Natural Science Foundation of China under Grant No.11174156
文摘The optimization of the fiber-coupled terahertz time-domain spectroscopy（THz-TDS） system is performed by changing the polarization of the optical excitation pulse centered at 1550 nm. In Ga As/In Al As multilayer structures based photoconductive antennas are used in TDS setup as both the emitter and receiver. The experimental results demonstrate that not only the THz signal power but also the temporal waveform vary with the rotation of the exciting pulse polarization. Maximum output power of the emitter is obtained when the polarization of the pump pulse is perpendicular to the edge of the metal electrodes. At this moment the THz waveform is close to a single-cycled pulse. However, double THz pulses could be recorded when the pump laser polarization is parallel to the electrodes. Laser pulse splitting induced by the birefringence of the optical fiber may attribute to the polarizationdependent performance of the fiber-coupled THz-TDS system.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61774130,11474248,61790581,and 51973070)the Ph.D.Program Foundation of the Ministry of Education of China(Grant No.20105303120002)the National Key Technology Research and Development Program of China(Grant No.2018YFA0209101)。
文摘A series of In Sb thin films were grown on Ga As substrates by molecular beam epitaxy(MBE).Ga Sb/Al In Sb is used as a compound buffer layer to release the strain caused by the lattice mismatch between the substrate and the epitaxial layer,so as to reduce the system defects.At the same time,the influence of different interface structures of Al In Sb on the surface morphology of buffer layer is explored.The propagation mechanism of defects with the growth of buffer layer is compared and analyzed.The relationship between the quality of In Sb thin films and the structure of buffer layer is summarized.Finally,the growth of high quality In Sb thin films is realized.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11274181,10974100,61203204,and 10674075)the Doctoral Scientific Fund Project of the Ministry of Education of China(Grant No.20120031110033)the Tianjin Key Program of Application Foundations and Future Technology Research Project,China(Grant No.10JCZDJC24300)
文摘A new polarization rotator based on the silica photonic crystal fiber is proposed. The proposed polarization rotator photonic crystal fiber （PR-PCF） possesses a triangle jigsaw-shape core region. The full-vector finite-element method is used to analyze the phenomenon of polarization conversion between the quasi-TE and quasi-TM modes. Numerical simulations show that the wavelengths of 1.31 μm and 1.55 μm are converted with a nearly 100% polarization conversion ratio with their matched coupling length and has a relatively strong realistic fabrication tolerance - 100 nm on the y axis and 50 nm on the x axis. The full vectorial finite difference beam propagation method is used to confirm the performance of the proposed PR-PCF.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11004111 and 61137001)the Natural Science Foundation of Tianjin City,China (Grant No. 10JCZDGX35100)+1 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20100031120034)the Fundamental Research Funds for the Central Universities of China
文摘A new approach is presented to reveal the temporal structure of femtosecond laser pulses by recording the correspond- ing time-resolved shadowgraphs of the laser-induced air plasma. It is shown that the temporal structures of femtosecond laser pulses, normally not observable by the ordinary intensity autocorrelator, can be detected through intuitively analyz- ing the ultrafast evolution process of the air plasma induced by the femtosecond laser pulses under examination. With this method, existence of pre- and post-pulses has been clearly unveiled within the time window of 4-150 fs in reference with the main 50-fs laser pulses output from a commercial 1-kHz femtosecond laser amplifier. The unique advantage of the proposed method is that it can directly provide valuable information about the pulse temporal structures＇ effect on the laser-induced ionization or material ablation.
基金supported by the National Natural Science Foundation of China(Grant No.61275133)
文摘Digital holography can be applied to ultrafast detection when a femtosecond laser pulse is used. In this paper, the interference process of two femtosecond laser pulses is studied and the recording process of the femtosecond laser pulsed digital hologram is simulated. Holograms at different recording angles are generated by integrating the instantaneous interference field. By analyzing the distribution of the reconstructed phase error, the characteristics of femtosecond laser pulsed digital holography are discussed.
基金Supported by the National High Technology Research and Development Program of China under Grant No 2011AA010205the National Natural Science Foundations of China under Grant Nos 61171027,10904076+1 种基金the Natural Science Foundation of Tianjin under Grant No 10JCZDJC152000the Doctoral Fund of Ministry of Education of China under Grant No 20090031110033.
文摘We demonstrate a photonic crystal cavity with a tapered waveguide and a point defect to highly confine terahertz waves.The terahertz wave is first guided into the tapered waveguide,gradually compressed to its end,and finally confined in the point defect cavity.Numerical simulations with the finite-difference time-domain method indicate that the narrow band terahertz wave is highly confined in the point defect cavity with a quality factor of 5323.The demonstrated device may be used as an antenna for enhancing light-matter interactions in the point defect cavity at terahertz frequencies and may improve the sensitivity of terahertz near-field microscopy.
基金supported by the National Natural Science Foundation of China(Nos.61036013,61138003,and 11204141)the support given by Tianjin Municipal Science and Technology Commission(No.11JCZDJC15200),the support provided by Tianjin Municipal Science and Technology Commission(No.12JCYBJC31000)
文摘We present a method of both polarization and amplitude modulations on an incident beam to obtain a longitudinally polarized subwavelength-sized optical needle. A 4-f system with a spatial light modulator is used to generate experimentally a two-mode alternate cylindrical vector beam by polarization modulation, enhancing performance and facilitating implementation. We optimize the beam focusing properties after passing the beam through an annular aperture to obtain amplitude modulation by the simulated annealing algorithm. Numerical results indicate that a sharp focal spot （0.417A） with a long focal depth （8A） and a strong longitudinally polarized field can be easily achieved.
基金financial support by the Guangdong Provincial Pearl River Talents Program(No.2019QN01C290)the Outstanding Young Scholar at South China Normal University,Guangdong Provincial Key Laboratory of Optical Information Materials and Technology under Grant(No.2023B1212060065)+1 种基金“Golden Seed”Extracurricular Scientific Research Project at South China Normal University(No.23HDKC06)National Center for International Research on Green Optoelectronics,MOE International Laboratory for Optical Information Technologies and the 111 Project(No.D16009).
文摘The controlled growth of perovskite nanowires along predefined orientations offers significant advantages over traditional post-growth assembly strategies,facilitating their integration into compact functional devices.In this study,a nanogroove-confined recrystallization process is designed for the precise and scalable growth of oriented perovskite nanowires with millimeter lengths and high crystallinity.The process involves annealing a perovskite-containing solution sandwiched between a hydrophobic flat silicon wafer and a hydrophilic faceted sapphire wafer featuring parallel nanogrooves at 90℃under ambient conditions.By customizing the electrode design,the nanowire arrays can be seamlessly integrated into monolithic photodetectors with large detection areas or into photodetector arrays with multiple microscale detector cells on their growth substrate.This in-situ integration strategy eliminates the need for complex post-growth processing steps.The photodetectors exhibit exceptional responsivity(38.4 A·W^(−1)),detectivity(4.35×10^(13)Jones),and response times in tens of microseconds across the ultraviolet-visible-near infrared ray(UV-vis-NIR)spectrum.The seamless integration of the nanowire photodetectors opens avenues for practical applications,including high-contrast optical imaging and efficient data transmission through Morse code encoding,leveraging their high on-off current ratios and rapid response.This innovative approach streamlines the growth of highly oriented perovskite nanowires,facilitating their integration into compact optoelectronic devices.
基金This work was supported by the National High Tech Projects(2012AA030402 and 2011AA010202)the National Science Foundation of China(61138001,61171024,61171026,61371035 and 11227904)+2 种基金the 111 Project(111-2-05)the Natural Science Foundation of Jiangsu Province(BK2012019)and the 973 Program(2014CB339800).
文摘The terahertz region is a special region of the electromagnetic spectrum that incorporates the advantages of both microwaves and infrared light waves.In the past decade,metamaterials with effective medium parameters or gradient phases have been studied to control terahertz waves and realize functional devices.Here,we present a new approach to manipulate terahertz waves by using coding metasurfaces that are composed of digital coding elements.We propose a general coding unit based on a Minkowski closed-loop particle that is capable of generating 1-bit coding(with two phase states of 0 and 180°),2-bit coding(with four phase states of 0,90°,180°,and 270°),and multi-bit coding elements in the terahertz frequencies by using different geometric scales.We show that multi-bit coding metasurfaces have strong abilities to control terahertz waves by designing-specific coding sequences.As an application,we demonstrate a new scattering strategy of terahertz waves—broadband and wide-angle diffusion—using a 2-bit coding metasurface with a special coding design and verify it by both numerical simulations and experiments.The presented method opens a new route to reducing the scattering of terahertz waves.
基金National Key R&D Program of China(2017YFC0821300)National Natural Science Foundation of China(NSFC)(11704252,11574160,61722111)+6 种基金National Program on Key Basic Research Project of China(973Program)(2014CB339802,2014CB339806)Major National Development Project of Scientific Instrument and Equipment(2017YFF0106300,2016YFF0100503)Tianjin Research Program of Application Foundation and Advanced Technology(15JCZDJC31700)Key Scientific and Technological Project of Science and Technology Commission of Shanghai Municipality(STCSM)(15DZ0500102)Shanghai Leading Talent(2016-019)Young Yangtze River Scholar(Q2016212)Tianjin Special Program for Talent Development
文摘In this work, it has been demonstrated that in order to fully understand the terahertz(THz) pulse generation process during femtosecond laser filamentation, the interaction between THz wave and air plasma has to be taken into account. This interaction is mainly associated with the spatial confinement of the THz pulse by the plasma column, which could be described by the one-dimensional negative dielectric(1DND) waveguide model. By combining the 1 DND model with the conventional four-wave mixing(4WM) and photocurrent(PC) models,the variation of THz spectral amplitude and width obtained in experiments could be better understood. Finally, a three-step procedure, with 1DND bridging 4WM and PC processes, has been established for the first time to describe the underlying mechanism of THz radiation from plasma sources.
基金financial support from the National Natural Science Foundation of China(Nos.21905253,51973200,51433003 and 21774041)the China Postdoctoral Science Foundation(2018M640681,2019T120632)+2 种基金JLU Science and Technology Innovative Research Team 2017TD-06Guangdong Provincial Key Laboratory of Optical Information Materials and Technology(No.2017B030301007)the Center of Advanced Analysis & Gene Sequencing,Zhengzhou University。
文摘Ammonia borane(NH_(3)BH_(3),AB) is promising for chemical hydrogen sto rage;however,current systems for rapid hydrogen production are limited by the expensive noble metal catalysts required for AB hydrolysis.Here we report the design and synthesis of a highly efficient and robust non-noble-metal catalyst for the hydrolysis of AB at 298 K(TOF=89.56 molH_(2) min^(-1) molCo^(-1)).Experiments and density functional theory calculations were performed to explore the catalyst’s hybrid nanoparticle heterostructure and its catalytic mechanism.The catalyst comprised nitrogen-doped carbon dots confining CoO and CoP,and exhibited strong interface-induced synergistic catalysis for AB hydrolysis that effectively decreased the energy barriers for the dissociation of both AB and water molecules.The co-doping of N and P introduced numerous defects,and further regulated the reactivity of the carbon layers.The heterogeneous interface design technique presented here provides a new strategy for developing efficient and inexpensive non-noblemetal catalysts that may be applicable in other fields related to energy catalysis.
基金supported by the Natural Science Foundation of Guangdong Province, China (No.2021B1515020087)the National Natural Science Foundation of China (No.51905178)。
文摘The laser scribing of polyimide(PI, Kapton) film is a new, simple and effective method for graphene preparation. Moreover,the superhydrophobic surface modification can undoubtedly widen the application fields of graphene. Herein, inspired by the hydrophobic and self-cleaning properties of natural Oxalis corniculata Linn. leaves, we propose a novel bionic manufacturing method for superhydrophobic laser-induced graphene(LIG). By tailoring the geometric parameters(size, roughness and height/area ratio) and chemical composition, the three-dimensional(3D) multistage LIG, i.e., with micro-jigsaw-like and porous structure, can deliver a static water contact angle(WCA) of 153.5° ± 0.6°, a water sliding angle(WSA) of 2.5° ±0.5°, and great superhydrophobic stability lasting for 100 days(WCAs ≈ 150°). This outstanding water repellency is achieved by the secondary structure of jigsaw-like LIG, a porous morphology that traps air layers at the solid–liquid interface. The robust self-cleaning and anti-stick functions of 3D bionic and multistage LIG are demonstrated to confirm its great potential in wearable electronics.
基金supported by the National Natural Science Foundation of China(Nos.60637020and11004111)the Tianjin Natural Science Foundation(No.10JCZDGX35100)the Open Fund of the State KeyLaboratory of Explosion Science and Technology(No.KFJJ-8)
文摘Femtosecond （fs） pulse laser ablation of silicon targets in air and in vacuum is investigated using a timeresolved shadowgraphic method. The observed dynamic process of the fs laser ablation of silicon in air is significantly different from that in vacuum. Similar to the ablation of metallic targets, while the shock wave front and a series of nearly concentric and semicircular stripes, as well as the contact front, are clearly identifiable in the process of ablation under 1 ×10^5 Pa, these phenomena are no longer observed when the ablation takes place in vacuum. Although the ambient air around the target strongly affects the evolution of the ablation plume, the three rounds of material ejection clearly observed in the shadowgraphs of fs laser ablation in standard air can also be distinguished in the process of ablation in vacuum. It is proven that the three rounds of material ejection are caused by different ablation mechanisms.
基金This work is supported partially by the National Major Research and Development Program(2019YFB1803902)National Natural Science Foundation of China(NSFC)(62135012,62105107)+3 种基金Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(2021R01001)Guangdong Basic and Applied Basic Research Foundation(2021A 1515012215,2021B1515120057)Science and Technology Planning Project of Guangdong Province(2019A050510039)Fundamental Research Funds for the Central Universities(2021QNA5001).
文摘Multi-lane integrated transmitter chips are key components in future compact optical modules to realize high-speed optical interconnects.Thin-film lithium niobate(TFLN)photonics have emerged as a promising platform for achieving high-performance chip-scale optical systems.Combining a coarse wavelength-division multiplexing(CWDM)devices using fabrication-tolerant angled multimode interferometer structure and high-performance electro-optical modulators,we demonstrate monolithic on-chip four-channel CWDM transmitter on the TFLN platform for the first time.The four-channel CWDM transmitter enables high-speed transmissions of 100 Gb/s data rate per wavelength channel(i.e.,an aggregated date rate of 400 Gb/s).
基金National Key Basic Research Program of China(2013CB328701)National Natural Science Foundation of China(NSFC)(61322508,11504270)
文摘The plasmonic nanogap antenna is an efficient radiating or receiving optical device. The resonance behavior of optical antennas is commonly attributed to the excitation of a localized surface plasmon resonance(LSPR), which can be theoretically defined as the quasi-normal mode(QNM). To clarify the physical origin of the LSPR, we build up an analytical model of the LSPR by considering a multiple scattering process of propagative surface plasmon polaritons(SPPs) on the antenna arms. The model can comprehensively reproduce the complex eigenfrequency and the field distribution of QNMs of the antenna, unveiling that the LSPR arises from a Fabry–Perot resonance of SPPs. By further applying the complex pole expansion theorem of meromorphic functions, the field of the antenna under illumination by a nearby dipole emitter can be analytically expanded with QNMs, which well predicts the frequency response of the enhancement factor of radiation. The present model establishes explicit relations between the concepts of the LSPR and the propagative SPP and integrates the advantages of the Fabry–Perot and QNM formalisms of nanogap antennas.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.11674177,61322510,and 61640408)Tianjin Natural Science Foundation(Nos.16JCZDJC31000 and 14JCZDJC31300)
文摘Passively mode-locked fiber lasers （PMLFLs） could be not only used as simple and economic ultrashort pulse sources but also as an ideal platform for exploring the nonlinear dynamics of dissipative solitons such as bound solitons, soliton rains, noise-like pulses, sideband-controllable solitons, soliton resonance,
基金financially supported by the National Natural Science Foundation of China (Nos. 51771127, 52171188 52111530143, 12104327, 51901081, 11974298 and 61961136006)the National Key Research and Development Program of China (No. 2020YFA0309300)+6 种基金Sichuan Science and Technology Program (Application No. 21ZYZYTS0077)the Science and Technology Program of Guangzhou (No. 202002030052)Guangdong Special Support Project (No. 2019BT02X030)Shenzhen Fundamental Research Fund (No. JCYJ20210324120213037)Shenzhen Peacock Group Plan (No. KQTD20180413181702403)Pearl River Recruitment Program of Talents (No. 2017GC010293)the Grants-in-Aid for Scientific Research from JSPS KAKENHI (Nos. JP20F20363, JP21H01364 and JP21K18872)
文摘Skyrmions are nano-scale quasi-particles with topological protection,which have potential applications in next-generation spintronics-based information storage.Numerous papers have been published to review various aspects of skyrmions,including physics,materials and applications.However,no review paper has focused on rare metals which play important roles in nucleating and manipulating skyrmions and other topological states.In this paper,various roles of rare metals have been classified and summarized,which can tune Curie temperature(TC),Dzyaloshinskii-Moriya interaction(DMI),magnetocrystalline anisotropy,Ruderman-Kittel-Kasuya-Yosida(RKKY)interaction and four-spin interaction so as to trigger the generation of skyrmions and other topological spin structures.The materials covered include typical B20 crystals,various layered systems with interfacial DMI,frustrated materials,antiferromagnets,ferrimagnets,twodimensional(2D)materials,etc.In addition,the rare-earth(RE)permanent magnets can provide an energy barrier and enrich the dynamic behaviors of skyrmions,which has also been reviewed.
