With the significant discharge of antibiotic wastewater into the aquatic and terrestrial ecosystems, antibiotic pollution has become a serious problem and presents a hazardous risk to the environment. To address such ...With the significant discharge of antibiotic wastewater into the aquatic and terrestrial ecosystems, antibiotic pollution has become a serious problem and presents a hazardous risk to the environment. To address such issues, various investigations on the removal of antibiotics have been undertaken. Photocatalysis has received tremendous attention owing to its great potential in removing antibiotics from aqueous solutions via a green, economic, and effective process. However, such a technology employing traditional photocatalysts suffers from major drawbacks such as light absorption being restricted to the UV spectrum only and fast charge recombination. To overcome these issues, considerable effort has been directed towards the development of advanced visible light-driven photocatalysts. This mini review summarises recent research progress in the state-of-the-art design and fabrication of photocatalysts with visible-light response for photocatalytic degradation of antibiotic wastewater. Such design strategies involve the doping of metal and non-metal into ultraviolet light-driven photocatalysts, development of new semiconductor photocatalysts, construction of heterojunction photocatalysts, and fabrication of surface plasmon resonance-enhanced photocatalytic systems. Additionally, some perspectives on the challenges and future developments in the area of photocatalytic degradation of antibiotics are provided.展开更多
Surface plasmon polaritons(SPPs)have been widely exploited in various scientific communities,ranging from physics,chemistry to biology,due to the strong confinement of light to the metal surface.For many applications,...Surface plasmon polaritons(SPPs)have been widely exploited in various scientific communities,ranging from physics,chemistry to biology,due to the strong confinement of light to the metal surface.For many applications,it is important that the free space photon can be coupled to SPPs in a controllable manner.In this Letter,we apply the concept of interfacial phase discontinuity for circularly polarizations on a metasurface to the design of a novel type of polarization-dependent SPP unidirectional excitation at normal incidence.Selective unidirectional excitation of SPPs along opposite directions is experimentally demonstrated at optical frequencies by simply switching the helicity of the incident light.This approach,in conjunction with dynamic polarization modulation techniques,opens gateway towards integrated plasmonic circuits with electrically reconfigurable functionalities.展开更多
Surface plasmon polaritons(SPPs)and their low-frequency counterparts(i.e.,spoof SPPs on artificial surfaces)have recently found numerous applications in photonics,but traditional devices to excite them(such as grating...Surface plasmon polaritons(SPPs)and their low-frequency counterparts(i.e.,spoof SPPs on artificial surfaces)have recently found numerous applications in photonics,but traditional devices to excite them(such as gratings and prism couplers)all suffer from problems of inherent low efficiency because the generated SPPs can decouple,returning to free space,and reflections at the device surface can never be avoided.Here,we propose a new SPP excitation scheme based on a transparent gradient metasurface and numerically demonstrate that it exhibits inherently high efficiency(~94%)because the designed meta-coupler suppresses both decoupling and surface reflections.As a practical realization of this concept,we fabricated a meta-coupler for operation in the microwave regime and performed near-field and far-field experiments to demonstrate that the achieved excitation efficiency for spoof SPPs reaches~73%,which is several times higher than that achieved by other available devices in this frequency domain.Our findings can motivate the design and fabrication of high-performance plasmonic devices to harvest light–matter interactions,particularly those related to spoof SPPs in the low-frequency domain.展开更多
Chicken is one of the most popular meat products in the world. Salmonella Typhimurium is a common foodbome pathogens associated with the processing of poultry. An optical Surface Plasmon Resonance （SPR） biosensor wa...Chicken is one of the most popular meat products in the world. Salmonella Typhimurium is a common foodbome pathogens associated with the processing of poultry. An optical Surface Plasmon Resonance （SPR） biosensor was sensitive to the presence of Salmonella Typhimurium in chicken carcass. The Spreeta biosensor kits were used to detect Salmonella Typhimurium on chicken carcass successfully. A taste sensor like electronic tongue or biosensors was used to basically ＂taste＂ the object and differentiated one object from the other with different taste sensor signatures. The surface plasmon resonance biosensor has potential for use in rapid, real-time detection and identification of bacteria, and to study the interaction of organisms with dif- ferent antisera or other molecular species. The selectivity of the SPR biosensor was assayed using a series of antibody con- centrations and dilution series of the organism. The SPR biosensor showed promising to detect the existence of Salmonella Typhimurium at 1 x 106 CFU/ml. Initial results show that the SPR biosensor has the potential for its application in pathogenic bacteria monitoring. However, more tests need to be done to confirm the detection limitation.展开更多
Plasmonic nonmetal semiconductors with localized surface plasmon resonance(LSPR)effects possess extended light-response ranges and can act as highly efficient H2 generation photocatalysts.Herein,an LSPR-enhanced 0D/2D...Plasmonic nonmetal semiconductors with localized surface plasmon resonance(LSPR)effects possess extended light-response ranges and can act as highly efficient H2 generation photocatalysts.Herein,an LSPR-enhanced 0D/2D CdS/MoO3‒x heterojunction has been synthesized by the growth of 0D CdS nanoparticles on 2D plasmonic MoO3‒x elliptical nanosheets via a simple coprecipitation method.Taking advantage of the LSPR effect of the MoO3‒x elliptical nanosheets,the light absorption of the CdS/MoO3‒x heterojunction was extended from 600 nm to the near-infrared region(1400 nm).Furthermore,the introduction of 2D plasmonic MoO3‒x elliptical nanosheets not only provided a platform for the growth of CdS nanoparticles,but also contributed to the construction of an LSPR-enhanced S-scheme structure due to the interface between the MoO3‒x and CdS,accelerating the separation of light-induced electrons and holes.Therefore,the CdS/MoO3‒x heterojunction exhibited higher photocatalytic H2 generation activity than pristine CdS under visible light irradiation,including under 420,450,550,and 650 nm monochromic light,as well as improved photo-corrosion performance.展开更多
Efficient excitation of surface plasmon polaritons(SPPs)remains one of the most challenging issues in areas of plasmonics related to information communication technologies.In particular,combining high SPP excitation e...Efficient excitation of surface plasmon polaritons(SPPs)remains one of the most challenging issues in areas of plasmonics related to information communication technologies.In particular,combining high SPP excitation efficiency and acceptance of any polarization of incident light appeared to be impossible to attain due to the polarized nature of SPPs.Here we demonstrate plasmonic couplers that represent arrays of gap SPP resonators producing upon reflection two orthogonal phase gradients in respective linear polarizations of incident radiation.These couplers are thereby capable of efficiently converting incident radiation with arbitrary polarization into SPPs that propagate in orthogonal directions dictated by the phase gradients.Fabricated couplers operate at telecom wavelengths and feature the coupling efficiency of,25%for either of two linear polarizations of incident radiation and directivity of SPP excitation exceeding 100.We further demonstrate that an individual wavelength-sized unit cell,representing a meta-scatterer,can also be used for efficient and polarization sensitive SPP excitation in compact plasmonics circuits.展开更多
High spatial frequency laser induced periodic surface structures(HSFLs)on silicon substrates are often developed on flat surfaces at low fluences near ablation threshold of 0.1 J/cm2,seldom on microstructures or micro...High spatial frequency laser induced periodic surface structures(HSFLs)on silicon substrates are often developed on flat surfaces at low fluences near ablation threshold of 0.1 J/cm2,seldom on microstructures or microgrooves at relatively higher fluences above 1 J/cm^2.This work aims to enrich the variety of HSFLs-containing hierarchical microstructures,by femtosecond laser(pulse duration:457 fs,wavelength:1045 nm,and repetition rate:100 kHz)in liquids(water and acetone)at laser fluence of 1.7 J/cm^2.The period of Si-HSFLs in the range of 110–200 nm is independent of the scanning speeds(0.1,0.5,1 and 2 mm/s),line intervals(5,15 and 20μm)of scanning lines and scanning directions(perpendicular or parallel to light polarization direction).It is interestingly found that besides normal HSFLs whose orientations are perpendicular to the direction of light polarization,both clockwise or anticlockwise randomly tilted HSFLs with a maximal deviation angle of 50°as compared to those of normal HSFLSs are found on the microstructures with height gradients.Raman spectra and SEM characterization jointly clarify that surface melting and nanocapillary waves play important roles in the formation of Si-HSFLs.The fact that no HSFLs are produced by laser ablation in air indicates that moderate melting facilitated with ultrafast liquid cooling is beneficial for the formation of HSFLs by LALs.On the basis of our findings and previous reports,a synergistic formation mechanism for HSFLs at high fluence was proposed and discussed,including thermal melting with the concomitance of ultrafast cooling in liquids,transformation of the molten layers into ripples and nanotips by surface plasmon polaritons(SPP)and second-harmonic generation(SHG),and modulation of Si-HSFLs direction by both nanocapillary waves and the localized electric field coming from the excited large Si particles.展开更多
We theoretically investigate high-order harmonic generation in a two-color multi-cycle inhomogeneous field combined with a 27th harmonic pulse. By considering a bowtie-shaped gold nanostructure, the spatiotemporal pro...We theoretically investigate high-order harmonic generation in a two-color multi-cycle inhomogeneous field combined with a 27th harmonic pulse. By considering a bowtie-shaped gold nanostructure, the spatiotemporal profiles of enhanced plasmonic fields are obtained by solving the Maxwell equation using finite-domain time-difference method. Based on quantum-mechanical and classical models, the effect of 27th harmonic pulse, temporal profile of enhanced plasmonic field and inhomogeneity on supercontinuum generation are analyzed and discussed. As a result, broadband supercontinuum can be generated from our approach with optimized gap size of nanostructure. Moreover, these results are not sensitively dependent on the relative phase in the two-color field.展开更多
Localized surface plasmon resonance(LSPR)can be supported by metallic nanoparticles and engineered nanostructures.An understanding of the spatially resolved near-field properties and dynamics of LSPR is important,but ...Localized surface plasmon resonance(LSPR)can be supported by metallic nanoparticles and engineered nanostructures.An understanding of the spatially resolved near-field properties and dynamics of LSPR is important,but remains experimentally challenging.We report experimental studies toward this aim using photoemission electron microscopy(PEEM)with high spatial resolution of sub-10 nm.Various engineered gold nanostructure arrays(such as rods,nanodisk-like particles and dimers)are investigated via PEEM using near-infrared(NIR)femtosecond laser pulses as the excitation source.When the LSPR wavelengths overlap the spectrum of the femtosecond pulses,the LSPR is efficiently excited and promotes multiphoton photoemission,which is correlated with the local intensity of the metallic nanoparticles in the near field.Thus,the local field distribution of the LSPR on different Au nanostructures can be directly explored and discussed using the PEEM images.In addition,the dynamics of the LSPR is studied by combining interferometric time-resolved pump-probe technique and PEEM.Detailed information on the oscillation and dephasing of the LSPR field can be obtained.The results identify PEEM as a powerful tool for accessing the near-field mapping and dynamic properties of plasmonic nanostructures.展开更多
Metamaterials and metasurfaces have attracted much attention due to their powerful ability to control electromagnetic(EM)waves.In this paper,we review the recent developments in the field of EM metamaterials,starting ...Metamaterials and metasurfaces have attracted much attention due to their powerful ability to control electromagnetic(EM)waves.In this paper,we review the recent developments in the field of EM metamaterials,starting from their exotic physics to their applications in novel information systems.First,we show the fundamental understanding on traditional metamaterials based on the effective medium theory and related applications,such as invisibility cloaks and meta-lenses.Second,we review the two-dimensional versions of metamaterials,i.e.,metasurfaces,for controlling spatial waves and surface waves and thereafter present their typical designs.In particular,we briefly introduce spoof surface plasmon polaritons and their applications in microwave frequencies.Following the above approach,we emphatically present the concepts of digital coding metamaterials,programmable metamaterials,and information metamaterials.By extending the principles of information science to metamaterial designs,several functional devices and information systems are presented,which enable digital and EM-wave manipulations simultaneously.Finally,we give a brief summary of the development prospects for microwave metamaterials.展开更多
Gas identification and concentration measurements are important for both understanding and monitoring a variety of phenomena from industrial processes to environmental change.Here a novel mid-IR plasmonic gas sensor w...Gas identification and concentration measurements are important for both understanding and monitoring a variety of phenomena from industrial processes to environmental change.Here a novel mid-IR plasmonic gas sensor with on-chip direct readout is proposed based on unity integration of narrowband spectral response,localized field enhancement and thermal detection.A systematic investigation consisting of both optical and thermal simulations for gas sensing is presented for the first time in three sensing modes including refractive index sensing,absorption sensing and spectroscopy,respectively.It is found that a detection limit less than 100 ppm for CO2 could be realized by a combination of surface plasmon resonance enhancement and metal-organic framework gas enrichment with an enhancement factor over 8000 in an ultracompact optical interaction length of only several microns.Moreover,on-chip spectroscopy is demonstrated with the compressive sensing algorithm via a narrowband plasmonic sensor array.An array of 80 such sensors with an average resonance linewidth of 10 nm reconstructs the CO2 molecular absorption spectrum with the estimated resolution of approximately 0.01 nm far beyond the state-of-the-art spectrometer.The novel device design and analytical method are expected to provide a promising technique for extensive applications of distributed or portable mid-IR gas sensor.展开更多
Among the many novel photocatalytic systems developed in very recent years,plasmonic photocatalytic composites possess great potential for use in applications and are one of the most intensively investigated photocata...Among the many novel photocatalytic systems developed in very recent years,plasmonic photocatalytic composites possess great potential for use in applications and are one of the most intensively investigated photocatalytic systems owing to their high solar energy utilization efficiency.In these composites,the plasmonic nanoparticles(PNPs)efficiently absorb solar light through localized surface plasmon resonance and convert it into energetic electrons and holes in the nearby semiconductor.This energy transfer from PNPs to semiconductors plays a decisive role in the overall photocatalytic performance.Thus,the underlying physical mechanism is of great scientific and technological importance and is one of the hottest topics in the area of plasmonic photocatalysts.In this review,we examine the very recent advances in understanding the energy transfer process in plasmonic photocatalytic composites,describing both the theoretical basis of this process and experimental demonstrations.The factors that affect the energy transfer efficiencies and how to improve the efficiencies to yield better photocatalytic performance are also discussed.Furthermore,comparisons are made between the various energy transfer processes,emphasizing their limitations/benefits for efficient operation of plasmonic photocatalysts.展开更多
An overview of recent researches of surface plasmon resonance （SPR） sensing technology in Laboratory of Science and Technology of Micro-Nano Optics （LMNO）, University of Science and Technology of China, is present...An overview of recent researches of surface plasmon resonance （SPR） sensing technology in Laboratory of Science and Technology of Micro-Nano Optics （LMNO）, University of Science and Technology of China, is presented. Some novel SPR sensors, such as sensors based on metallic grating, metal-insulator-metal （MIM） nanoring and optical fiber, are designed or fabricated and tested. The sensor based on localized surface plasmon resonance （LSPR） of metallic nanoparticles is also be summarized. Because of the coupling of propagating surface plasmons and localized surface plasmons, the localized electromagnetic field is extremely enhanced, which is applied to surface-enhanced Raman scattering （SERS） and fluorenscence enhancement. Future prospects of SPR and/or LSPR sensing developments and applications are atso discussed.展开更多
Using the finite-difference time-domain(FDTD) method,we simulate the coupling between a gold nanorod and gold nanoparticles with different plasmonic resonant frequencies/volumes as well as that between the nanorod and...Using the finite-difference time-domain(FDTD) method,we simulate the coupling between a gold nanorod and gold nanoparticles with different plasmonic resonant frequencies/volumes as well as that between the nanorod and a dielectric nanosphere.The influences of coupling with different nanoparticles on the excitation of a forbidden longitudinal surface plasmon mode of the nanorod under normal incidence are investigated.It is found that the cause of this excitation is the broken symmetry of the local electric field experienced by the nanorod resulting from the charge pileup on the other nanoparticle.This result is valuable for understanding the near-field optical characterization of plasmonic metal nanoparticles.展开更多
Bi2WO6 is a typical visible-light-responsive semiconductor photocatalyst with a layered structure.However,the relatively large bandgap(2.6–2.8 eV)and quick recombination of photo-generated carriers result in its low ...Bi2WO6 is a typical visible-light-responsive semiconductor photocatalyst with a layered structure.However,the relatively large bandgap(2.6–2.8 eV)and quick recombination of photo-generated carriers result in its low quantum efficiency.In this paper,Bi-nanospheres-modified flower-like Bi2WO6 was successfully prepared by solvothermal treatment of Bi2WO6 powders in Bi(NO3)3 solution using ethylene glycol as reductant.The photoreactivity of this photocatalyst was evaluated by the oxidation of NO in a continuous-flow reactor under irradiation by a visible LED lamp(λ>400 nm).It was found that both Bi nanospheres and flower-like Bi2WO6 precursor exhibit very poor photocatalytic activity with NO removal rates of only 7.7%and 8.6%,respectively.The photoreactivity of Bi/Bi2WO6 was found to steadily increase from 12.3%to 53.1%with increase in the amount of Bi nanospheres from 0 to 10 wt%.However,with further increase in the loading amount of Bi nanospheres,the photoreactivity of Bi/Bi2WO6 hybridized photocatalyst begins to decrease,possibly due to the light filtering by the Bi nanospheres.The enhanced visible photoreactivity of Bi/Bi2WO6 towards NO abatement was attributed to surface plasmon resonance driven interfacial charge separation.The excellent stability of Bi/Bi2WO6 hybridized photocatalyst towards NO oxidation demonstrates its potential for applications such as air purification.展开更多
Miniaturization has been an everlasting theme in the development of semiconductor lasers.One important breakthrough in this process in recent years is the use of metal-dielectric composite structures that made truly s...Miniaturization has been an everlasting theme in the development of semiconductor lasers.One important breakthrough in this process in recent years is the use of metal-dielectric composite structures that made truly subwavelength lasers possible.Many different designs of metallic cavity semiconductor nanolasers have been proposed and demonstrated.In this article,we will review some of the most exciting progresses in this newly emerging field.In particular,we will focus on metallic-cavity nanolasers with volume smaller than wavelength cubed under electrical injection with emphasis on high-temperature operation.Such devices will serve as an important component in the future integrated nanophotonic systems due to its ultra-small size.展开更多
基金supported by the National Natural Science Foundation of China(21421001,21276116,21477050,21301076,21303074)Natural Science Foundation of Jiangsu Province(BK20140530,BK20150482)+5 种基金China Postdoctoral Science Foundation(2015M570409)Chinese-German Cooperation Research Project(GZ1091)Program for High-Level Innovative and Entrepreneurial Talents in Jiangsu ProvinceProgram for New Century Excellent Talents in University(NCET-13-0835)Henry Fok Education Foundation(141068)Six Talents Peak Project in Jiangsu Province(XCL-025)~~
文摘With the significant discharge of antibiotic wastewater into the aquatic and terrestrial ecosystems, antibiotic pollution has become a serious problem and presents a hazardous risk to the environment. To address such issues, various investigations on the removal of antibiotics have been undertaken. Photocatalysis has received tremendous attention owing to its great potential in removing antibiotics from aqueous solutions via a green, economic, and effective process. However, such a technology employing traditional photocatalysts suffers from major drawbacks such as light absorption being restricted to the UV spectrum only and fast charge recombination. To overcome these issues, considerable effort has been directed towards the development of advanced visible light-driven photocatalysts. This mini review summarises recent research progress in the state-of-the-art design and fabrication of photocatalysts with visible-light response for photocatalytic degradation of antibiotic wastewater. Such design strategies involve the doping of metal and non-metal into ultraviolet light-driven photocatalysts, development of new semiconductor photocatalysts, construction of heterojunction photocatalysts, and fabrication of surface plasmon resonance-enhanced photocatalytic systems. Additionally, some perspectives on the challenges and future developments in the area of photocatalytic degradation of antibiotics are provided.
基金This work is partly supported by the Engineering and Physical Sciences Council of the United KingdomTZ acknowledges the financial support by the European Commission under the Marie Curie Fellowship Program and the Deutsche Forschungsgemeinschaft(DFG)through the priority program SPP 1391+2 种基金LH would like to acknowledge the Chinese Scholarship Council(CSC,No.2011621202)for financial supportBB and LH acknowledge the support by the National Natural Science Foundation of China(Projects No.61227014,No.11004119,and No.61161130005)the Ministry of Science and Technology of China(Project No.2011BAK15B03)
文摘Surface plasmon polaritons(SPPs)have been widely exploited in various scientific communities,ranging from physics,chemistry to biology,due to the strong confinement of light to the metal surface.For many applications,it is important that the free space photon can be coupled to SPPs in a controllable manner.In this Letter,we apply the concept of interfacial phase discontinuity for circularly polarizations on a metasurface to the design of a novel type of polarization-dependent SPP unidirectional excitation at normal incidence.Selective unidirectional excitation of SPPs along opposite directions is experimentally demonstrated at optical frequencies by simply switching the helicity of the incident light.This approach,in conjunction with dynamic polarization modulation techniques,opens gateway towards integrated plasmonic circuits with electrically reconfigurable functionalities.
基金supported by the National Natural Science Foundation of China(Nos.11474057,11174055,11204040,and 11404063)the MOE of China(B06011)the Shanghai Science and Technology Committee(grant No.14PJ1401200).
文摘Surface plasmon polaritons(SPPs)and their low-frequency counterparts(i.e.,spoof SPPs on artificial surfaces)have recently found numerous applications in photonics,but traditional devices to excite them(such as gratings and prism couplers)all suffer from problems of inherent low efficiency because the generated SPPs can decouple,returning to free space,and reflections at the device surface can never be avoided.Here,we propose a new SPP excitation scheme based on a transparent gradient metasurface and numerically demonstrate that it exhibits inherently high efficiency(~94%)because the designed meta-coupler suppresses both decoupling and surface reflections.As a practical realization of this concept,we fabricated a meta-coupler for operation in the microwave regime and performed near-field and far-field experiments to demonstrate that the achieved excitation efficiency for spoof SPPs reaches~73%,which is several times higher than that achieved by other available devices in this frequency domain.Our findings can motivate the design and fabrication of high-performance plasmonic devices to harvest light–matter interactions,particularly those related to spoof SPPs in the low-frequency domain.
文摘Chicken is one of the most popular meat products in the world. Salmonella Typhimurium is a common foodbome pathogens associated with the processing of poultry. An optical Surface Plasmon Resonance （SPR） biosensor was sensitive to the presence of Salmonella Typhimurium in chicken carcass. The Spreeta biosensor kits were used to detect Salmonella Typhimurium on chicken carcass successfully. A taste sensor like electronic tongue or biosensors was used to basically ＂taste＂ the object and differentiated one object from the other with different taste sensor signatures. The surface plasmon resonance biosensor has potential for use in rapid, real-time detection and identification of bacteria, and to study the interaction of organisms with dif- ferent antisera or other molecular species. The selectivity of the SPR biosensor was assayed using a series of antibody con- centrations and dilution series of the organism. The SPR biosensor showed promising to detect the existence of Salmonella Typhimurium at 1 x 106 CFU/ml. Initial results show that the SPR biosensor has the potential for its application in pathogenic bacteria monitoring. However, more tests need to be done to confirm the detection limitation.
文摘Plasmonic nonmetal semiconductors with localized surface plasmon resonance(LSPR)effects possess extended light-response ranges and can act as highly efficient H2 generation photocatalysts.Herein,an LSPR-enhanced 0D/2D CdS/MoO3‒x heterojunction has been synthesized by the growth of 0D CdS nanoparticles on 2D plasmonic MoO3‒x elliptical nanosheets via a simple coprecipitation method.Taking advantage of the LSPR effect of the MoO3‒x elliptical nanosheets,the light absorption of the CdS/MoO3‒x heterojunction was extended from 600 nm to the near-infrared region(1400 nm).Furthermore,the introduction of 2D plasmonic MoO3‒x elliptical nanosheets not only provided a platform for the growth of CdS nanoparticles,but also contributed to the construction of an LSPR-enhanced S-scheme structure due to the interface between the MoO3‒x and CdS,accelerating the separation of light-induced electrons and holes.Therefore,the CdS/MoO3‒x heterojunction exhibited higher photocatalytic H2 generation activity than pristine CdS under visible light irradiation,including under 420,450,550,and 650 nm monochromic light,as well as improved photo-corrosion performance.
基金The authors would like to acknowledge the financial support from the Danish Council for Independent Research(the FTP project ANAP,contract no.09-072949,and the FNU project,contract no.12-124690).
文摘Efficient excitation of surface plasmon polaritons(SPPs)remains one of the most challenging issues in areas of plasmonics related to information communication technologies.In particular,combining high SPP excitation efficiency and acceptance of any polarization of incident light appeared to be impossible to attain due to the polarized nature of SPPs.Here we demonstrate plasmonic couplers that represent arrays of gap SPP resonators producing upon reflection two orthogonal phase gradients in respective linear polarizations of incident radiation.These couplers are thereby capable of efficiently converting incident radiation with arbitrary polarization into SPPs that propagate in orthogonal directions dictated by the phase gradients.Fabricated couplers operate at telecom wavelengths and feature the coupling efficiency of,25%for either of two linear polarizations of incident radiation and directivity of SPP excitation exceeding 100.We further demonstrate that an individual wavelength-sized unit cell,representing a meta-scatterer,can also be used for efficient and polarization sensitive SPP excitation in compact plasmonics circuits.
文摘High spatial frequency laser induced periodic surface structures(HSFLs)on silicon substrates are often developed on flat surfaces at low fluences near ablation threshold of 0.1 J/cm2,seldom on microstructures or microgrooves at relatively higher fluences above 1 J/cm^2.This work aims to enrich the variety of HSFLs-containing hierarchical microstructures,by femtosecond laser(pulse duration:457 fs,wavelength:1045 nm,and repetition rate:100 kHz)in liquids(water and acetone)at laser fluence of 1.7 J/cm^2.The period of Si-HSFLs in the range of 110–200 nm is independent of the scanning speeds(0.1,0.5,1 and 2 mm/s),line intervals(5,15 and 20μm)of scanning lines and scanning directions(perpendicular or parallel to light polarization direction).It is interestingly found that besides normal HSFLs whose orientations are perpendicular to the direction of light polarization,both clockwise or anticlockwise randomly tilted HSFLs with a maximal deviation angle of 50°as compared to those of normal HSFLSs are found on the microstructures with height gradients.Raman spectra and SEM characterization jointly clarify that surface melting and nanocapillary waves play important roles in the formation of Si-HSFLs.The fact that no HSFLs are produced by laser ablation in air indicates that moderate melting facilitated with ultrafast liquid cooling is beneficial for the formation of HSFLs by LALs.On the basis of our findings and previous reports,a synergistic formation mechanism for HSFLs at high fluence was proposed and discussed,including thermal melting with the concomitance of ultrafast cooling in liquids,transformation of the molten layers into ripples and nanotips by surface plasmon polaritons(SPP)and second-harmonic generation(SHG),and modulation of Si-HSFLs direction by both nanocapillary waves and the localized electric field coming from the excited large Si particles.
基金supported by the National Natural Science Foundation of China(Grants Nos.11404153,11175076,11135002,and 11405077)the Fundamental Research Funds for the Central Universities of China(Grant Nos.lzujbky-2014-10,lzujbky-2014-13,and lzujbky-2014-14)
文摘We theoretically investigate high-order harmonic generation in a two-color multi-cycle inhomogeneous field combined with a 27th harmonic pulse. By considering a bowtie-shaped gold nanostructure, the spatiotemporal profiles of enhanced plasmonic fields are obtained by solving the Maxwell equation using finite-domain time-difference method. Based on quantum-mechanical and classical models, the effect of 27th harmonic pulse, temporal profile of enhanced plasmonic field and inhomogeneity on supercontinuum generation are analyzed and discussed. As a result, broadband supercontinuum can be generated from our approach with optimized gap size of nanostructure. Moreover, these results are not sensitively dependent on the relative phase in the two-color field.
基金This study was supported by funding from the Ministry of Education,Culture,Sports,Science,and Technology of Japan:KAKENHI Grant-in-Aid for Scientific Research No.23225006,Nanotechnology Platform(Hokkaido University)and the Low-Carbon Research Network of Japan.
文摘Localized surface plasmon resonance(LSPR)can be supported by metallic nanoparticles and engineered nanostructures.An understanding of the spatially resolved near-field properties and dynamics of LSPR is important,but remains experimentally challenging.We report experimental studies toward this aim using photoemission electron microscopy(PEEM)with high spatial resolution of sub-10 nm.Various engineered gold nanostructure arrays(such as rods,nanodisk-like particles and dimers)are investigated via PEEM using near-infrared(NIR)femtosecond laser pulses as the excitation source.When the LSPR wavelengths overlap the spectrum of the femtosecond pulses,the LSPR is efficiently excited and promotes multiphoton photoemission,which is correlated with the local intensity of the metallic nanoparticles in the near field.Thus,the local field distribution of the LSPR on different Au nanostructures can be directly explored and discussed using the PEEM images.In addition,the dynamics of the LSPR is studied by combining interferometric time-resolved pump-probe technique and PEEM.Detailed information on the oscillation and dephasing of the LSPR field can be obtained.The results identify PEEM as a powerful tool for accessing the near-field mapping and dynamic properties of plasmonic nanostructures.
基金supported by the National Key Research and Development Program of China(Nos.2017YFA0700201,2017YFA0700202,and 2017YFA0700203)the National Natural Science Foundation of China(Nos.61631007,61731010,61735010,61722106,61701107,and 61701108)+3 种基金the Fund for International Cooperation and Exchange of the National Natural Science Foundation of China(No.61761136007)the 111 Project(No.111-2-05)the Fundamental Research Funds for the Central Universities,the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(No.KYCX17_0092)the Scientific Research Foundation of Graduate School of Southeast University,China(No.YBJJ-1815)。
文摘Metamaterials and metasurfaces have attracted much attention due to their powerful ability to control electromagnetic(EM)waves.In this paper,we review the recent developments in the field of EM metamaterials,starting from their exotic physics to their applications in novel information systems.First,we show the fundamental understanding on traditional metamaterials based on the effective medium theory and related applications,such as invisibility cloaks and meta-lenses.Second,we review the two-dimensional versions of metamaterials,i.e.,metasurfaces,for controlling spatial waves and surface waves and thereafter present their typical designs.In particular,we briefly introduce spoof surface plasmon polaritons and their applications in microwave frequencies.Following the above approach,we emphatically present the concepts of digital coding metamaterials,programmable metamaterials,and information metamaterials.By extending the principles of information science to metamaterial designs,several functional devices and information systems are presented,which enable digital and EM-wave manipulations simultaneously.Finally,we give a brief summary of the development prospects for microwave metamaterials.
基金We are grateful for financial supports from National Key Research and Development Program of China(No.2019YFB2203402)National Natural Science Foundation of China(Nos.11774383,11774099,11874029)+3 种基金Guangdong Science and Technology Program International Cooperation Program(2018A050506039)Guangdong Natural Science Founds for Distinguished Young Scholars(No.2020B151502074),Pearl River Talent Plan Program of Guangdong(No.2019QN01X120)Fundamental Research Funds for the Central Universities,Royal Society Newton Advanced Fellowship(No.NA140301)Key Frontier Scientific Research Program of the Chinese Academy of Sciences(No.QYZDBSSW-JSC014).
文摘Gas identification and concentration measurements are important for both understanding and monitoring a variety of phenomena from industrial processes to environmental change.Here a novel mid-IR plasmonic gas sensor with on-chip direct readout is proposed based on unity integration of narrowband spectral response,localized field enhancement and thermal detection.A systematic investigation consisting of both optical and thermal simulations for gas sensing is presented for the first time in three sensing modes including refractive index sensing,absorption sensing and spectroscopy,respectively.It is found that a detection limit less than 100 ppm for CO2 could be realized by a combination of surface plasmon resonance enhancement and metal-organic framework gas enrichment with an enhancement factor over 8000 in an ultracompact optical interaction length of only several microns.Moreover,on-chip spectroscopy is demonstrated with the compressive sensing algorithm via a narrowband plasmonic sensor array.An array of 80 such sensors with an average resonance linewidth of 10 nm reconstructs the CO2 molecular absorption spectrum with the estimated resolution of approximately 0.01 nm far beyond the state-of-the-art spectrometer.The novel device design and analytical method are expected to provide a promising technique for extensive applications of distributed or portable mid-IR gas sensor.
基金supported by the National Basic Research Program of China(973 program,2013CB632401)the National Science Foundation of China(Grant NOs 11374190 and 21333006)the Taishan Scholar Program of Shandong and 111 Project B13029.
文摘Among the many novel photocatalytic systems developed in very recent years,plasmonic photocatalytic composites possess great potential for use in applications and are one of the most intensively investigated photocatalytic systems owing to their high solar energy utilization efficiency.In these composites,the plasmonic nanoparticles(PNPs)efficiently absorb solar light through localized surface plasmon resonance and convert it into energetic electrons and holes in the nearby semiconductor.This energy transfer from PNPs to semiconductors plays a decisive role in the overall photocatalytic performance.Thus,the underlying physical mechanism is of great scientific and technological importance and is one of the hottest topics in the area of plasmonic photocatalysts.In this review,we examine the very recent advances in understanding the energy transfer process in plasmonic photocatalytic composites,describing both the theoretical basis of this process and experimental demonstrations.The factors that affect the energy transfer efficiencies and how to improve the efficiencies to yield better photocatalytic performance are also discussed.Furthermore,comparisons are made between the various energy transfer processes,emphasizing their limitations/benefits for efficient operation of plasmonic photocatalysts.
基金This work is supported by the National Key Basic Research Program of China （No. 2011cb301802）, and Key Program of National Natural Science Foundation of China （No. 60736037）. The authors gratefully acknowledge Prof. Y. H. Lu, D. G. Zhang, and P. Wang for many helpful discussions.
文摘An overview of recent researches of surface plasmon resonance （SPR） sensing technology in Laboratory of Science and Technology of Micro-Nano Optics （LMNO）, University of Science and Technology of China, is presented. Some novel SPR sensors, such as sensors based on metallic grating, metal-insulator-metal （MIM） nanoring and optical fiber, are designed or fabricated and tested. The sensor based on localized surface plasmon resonance （LSPR） of metallic nanoparticles is also be summarized. Because of the coupling of propagating surface plasmons and localized surface plasmons, the localized electromagnetic field is extremely enhanced, which is applied to surface-enhanced Raman scattering （SERS） and fluorenscence enhancement. Future prospects of SPR and/or LSPR sensing developments and applications are atso discussed.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 10821062 and 10804004)the National Basic Research Program of China (Grant No. 2007CB307001)the Specialized Research Fund for the Doctoral Program of Higher Education (Grant No. 200800011023) Contributed by GONG QiHuang
文摘Using the finite-difference time-domain(FDTD) method,we simulate the coupling between a gold nanorod and gold nanoparticles with different plasmonic resonant frequencies/volumes as well as that between the nanorod and a dielectric nanosphere.The influences of coupling with different nanoparticles on the excitation of a forbidden longitudinal surface plasmon mode of the nanorod under normal incidence are investigated.It is found that the cause of this excitation is the broken symmetry of the local electric field experienced by the nanorod resulting from the charge pileup on the other nanoparticle.This result is valuable for understanding the near-field optical characterization of plasmonic metal nanoparticles.
基金supported by the National Natural Science Foundation of China(51672312,21373275,51808080,21571192)the Fundamental Research Funds for the Central Univsrsity,South-Central University for Nationalities(CZT19006)+2 种基金the Natural Science Foundation Project of CQ CSTC(cstc2018jcyjA 3794)China "post-doctoral innovative talent support program"(BX20180056)China Postdoctoral Science Foundation(2018M643788XB)~~
文摘Bi2WO6 is a typical visible-light-responsive semiconductor photocatalyst with a layered structure.However,the relatively large bandgap(2.6–2.8 eV)and quick recombination of photo-generated carriers result in its low quantum efficiency.In this paper,Bi-nanospheres-modified flower-like Bi2WO6 was successfully prepared by solvothermal treatment of Bi2WO6 powders in Bi(NO3)3 solution using ethylene glycol as reductant.The photoreactivity of this photocatalyst was evaluated by the oxidation of NO in a continuous-flow reactor under irradiation by a visible LED lamp(λ>400 nm).It was found that both Bi nanospheres and flower-like Bi2WO6 precursor exhibit very poor photocatalytic activity with NO removal rates of only 7.7%and 8.6%,respectively.The photoreactivity of Bi/Bi2WO6 was found to steadily increase from 12.3%to 53.1%with increase in the amount of Bi nanospheres from 0 to 10 wt%.However,with further increase in the loading amount of Bi nanospheres,the photoreactivity of Bi/Bi2WO6 hybridized photocatalyst begins to decrease,possibly due to the light filtering by the Bi nanospheres.The enhanced visible photoreactivity of Bi/Bi2WO6 towards NO abatement was attributed to surface plasmon resonance driven interfacial charge separation.The excellent stability of Bi/Bi2WO6 hybridized photocatalyst towards NO oxidation demonstrates its potential for applications such as air purification.
基金Research reported in this article in the authors group was supported by the Defense Advanced Research Project Agency program Nanoscale Architectures of Coherent Hyper-Optical Sources(grant no.W911-NF07-1-0314)by the Air Force Office of Scientific Research(grant no.FA9550-10-1-0444,Gernot Pomrenke)We thank Martin Hill for his collaboration over the last few years.
文摘Miniaturization has been an everlasting theme in the development of semiconductor lasers.One important breakthrough in this process in recent years is the use of metal-dielectric composite structures that made truly subwavelength lasers possible.Many different designs of metallic cavity semiconductor nanolasers have been proposed and demonstrated.In this article,we will review some of the most exciting progresses in this newly emerging field.In particular,we will focus on metallic-cavity nanolasers with volume smaller than wavelength cubed under electrical injection with emphasis on high-temperature operation.Such devices will serve as an important component in the future integrated nanophotonic systems due to its ultra-small size.
