The properties of propagating surface plasmon polaritons(SPPs)along one-dimensional metal structures have been investigated for more than 10 years and are now well understood.Because of the high confinement of electro...The properties of propagating surface plasmon polaritons(SPPs)along one-dimensional metal structures have been investigated for more than 10 years and are now well understood.Because of the high confinement of electromagnetic energy,propagating SPPs have been considered to represent one of the best potential ways to construct next-generation circuits that use light to overcome the speed limit of electronics.Many basic plasmonic components have already been developed.In this review,researches on plasmonic waveguides are reviewed from the perspective of plasmonic circuits.Several circuit components are constructed to demonstrate the basic function of an optical digital circuit.In the end of this review,a prototype for an SPP-based nanochip is proposed,and the problems associated with building such plasmonic circuits are discussed.A plasmonic chip that can be practically applied is expected to become available in the near future.展开更多
Light collection efficiency is an important factor that affects the performance of many optical and optoelectronic devices.In these devices,the high reflectivity of interfaces can hinder efficient light collection.To ...Light collection efficiency is an important factor that affects the performance of many optical and optoelectronic devices.In these devices,the high reflectivity of interfaces can hinder efficient light collection.To minimize unwanted reflection,anti-reflection surfaces can be fabricated by micro/nanopatterning.In this paper,we investigate the fabrication of broadband anti-reflection Si surfaces by laser micro/nanoprocessing.Laser direct writing is applied to create microstructures on Si surfaces that reduce light reflection by light trapping.In addition,laser interference lithography and metal assisted chemical etching are adopted to fabricate the Si nanowire arrays.The anti-reflection performance is greatly improved by the high aspect ratio subwavelength structures,which create gradients of refractive index from the ambient air to the substrate.Furthermore,by decoration of the Si nanowires with metallic nanoparticles,surface plasmon resonance can be used to further control the broadband reflections,reducing the reflection to below 1.0%across from 300 to 1200 nm.An average reflection of 0.8%is achieved.展开更多
Light scattering by small particles has a long and interesting history in physics.Nonetheless,it continues to surprise with new insights and applications.This includes new discoveries,such as novel plasmonic effects,a...Light scattering by small particles has a long and interesting history in physics.Nonetheless,it continues to surprise with new insights and applications.This includes new discoveries,such as novel plasmonic effects,as well as exciting theoretical and experimental developments such as optical trapping,anomalous light scattering,optical tweezers,nanospasers,and novel aspects and realizations of Fano resonances.These have led to important new applications,including several ones in the biomedical area and in sensing techniques at the single-molecule level.There are additionally many potential future applications in optical devices and solar energy technologies.Here we review the fundamental aspects of light scattering by small spherical particles,emphasizing the phenomenological treatments and new developments in this field.展开更多
Metasurfaces,with extremely exotic capabilities to manipulate electromagnetic(EM)waves,have derived a plethora of advanced metadevices with intriguing functionalities.Tremendous endeavors have been mainly devoted to t...Metasurfaces,with extremely exotic capabilities to manipulate electromagnetic(EM)waves,have derived a plethora of advanced metadevices with intriguing functionalities.Tremendous endeavors have been mainly devoted to the static metasurfaces and metadevices,where the functionalities cannot be actively tuned in situ post-fabrication.Due to the in-trinsic advantage of active tunability by external stimulus,graphene has been successively demonstrated as a favorable candidate to empower metasurfaces with remarkably dynamic tunability,and their recent advances are propelling the EM wave manipulations to a new height:from static to dynamic.Here,we review the recent progress on dynamic metasur-faces and metadevices enabled by graphene with the focus on electrically-controlled dynamic manipulation of the EM waves covering the mid-infrared,terahertz,and microwave regimes.The fundamentals of graphene,including basic ma-terial properties and plasmons,are first discussed.Then,graphene-empowered dynamic metasurfaces and met-adevices are divided into two categories,i.e.,metasurfaces with building blocks of structured graphene and hybrid metasurfaces integrated with graphene,and their recent advances in dynamic spectrum manipulation,wavefront shap-ing,polarization control,and frequency conversion in near/far fields and global/local ways are elaborated.In the end,we summarize the progress,outline the remaining challenges,and prospect the potential future developments.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
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
We give a brief review of the developments in terahertz time-domain spectroscopy(THz-TDS) systems and microcavity components for probing samples in the University of Shanghai for Science and Technology. The broadband ...We give a brief review of the developments in terahertz time-domain spectroscopy(THz-TDS) systems and microcavity components for probing samples in the University of Shanghai for Science and Technology. The broadband terahertz(THz) radiation sources based on GaAs m-i-n diodes have been investigated by applying high electric fields. Then, the free space THz-TDS and fiber-coupled THz-TDS systems produced in our lab and their applications in drug/cancer detection are introduced in detail. To further improve the signal-to-noise ratio(SNR) and enhance sensitivity, we introduce three general micro-cavity approaches to achieve tiny-volume sample detection, summarizing our previous results about their characteristics, performance, and potential applications.展开更多
We investigated the effect of photodynamic therapy （PDT） with hematoporphyrin monomethyl ether （HMME） on the viability of Streptococcus mutans （S. mutans） cells on biofilms in vitro. Streptococcus mutans is the ...We investigated the effect of photodynamic therapy （PDT） with hematoporphyrin monomethyl ether （HMME） on the viability of Streptococcus mutans （S. mutans） cells on biofilms in vitro. Streptococcus mutans is the primary etiological agent of human dental caries. Since dental caries are localized infections, such plaque-related diseases would be well suited to PDT. The diode laser used in this study had the wavelength of 635 nm, whose output power was 10 mW and the energy density was 12.74 J/cm^2. HMME was used as photosensitizer. Samples were prepared and divided into five groups： （1） HMME; （2） Laser; （3） HMME＋Laser; （4） Control group （＋） with chlorhexidine; and （5） Control group （-） with sterile physiological saline. Inoculum of S. mutans incubated with HMME also examined with fluorescence microscopy. PDT exhibited a significantly （P 〈 0.05） increased antimicrobial potential compared with 20 μm/mL HMME only, laser only, 0.05% chlorhexidine, and 0.9% sterile physiological saline, which reduced the S. mutans of the biofilm most effectively. Laser and 0.05% chlorhexidine were caused reduction in the viable counts of S. mutans significantly different （P 〈 0.05） also, but these two test treatments did not statistically differ from each other. HMME group did not statistically differ with negative control group. Fluorescence microscopy indicated that HMME localized primarily in the S. mutans of the biofilm. It was demonstrated that HMME-mediated PDT was efficient at killing S. mutans of biofilms and a useful approach in the treatment of dental plaque-related diseases.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
We review some of the recent advances in the development of subwavelength plasmonic devices for manipulating light at the nanoseale, drawing examples from our own work in metal-dielectric-metal （MDM） plasmonic waveg...We review some of the recent advances in the development of subwavelength plasmonic devices for manipulating light at the nanoseale, drawing examples from our own work in metal-dielectric-metal （MDM） plasmonic waveguide devices. We introduce bends, splitters, and mode converters for MDM waveguides with no additional loss. We also demonstrate that optical gain provides a mechanism for on/off switching in MDM plasmonic waveguides. Highly efficient compact couplers between dielectric waveguides and MDM waveguides are also introduced.展开更多
We present a review of terahertz plasmonic metamaterial devices that have functionalities and applications ranging from sensing, enhanced electromagnetic fields, and near field manipulation. Metamaterials allow the pr...We present a review of terahertz plasmonic metamaterial devices that have functionalities and applications ranging from sensing, enhanced electromagnetic fields, and near field manipulation. Metamaterials allow the properties of light propagation to be manipulated at will by using a combination of appropriately designed geometry and suitable materials at the unit cell level. In this review, we first discuss the sensing aspect of a planar plasmonic metamaterial and how to overcome its limitations. Conventional symmetric metamaterials are limited by their low Q factor, thus we probed the symmetry broken plasmonic metama- terial structures in which the interference between a broad continuum mode and a narrow localized mode leads to the excitation of the sharp Fano resonances. We also discuss the near field mediated excitation of dark plasmonic modes in metamaterials that is caused by a strong coupling from the bright mode res- onator. The near field coupling between the dark and bright mode resonances leads to classical analogue of electromagnetically induced transparency in plasmonic systems. Finally, we discuss active switching in terahertz metamateriMs based on high temperature superconductors that holds the promise of reducing the resistive losses in these systems, though it fails to suppress the radiation loss in plasmonic metamaterial at terahertz frequencies.展开更多
We experimentally investigated remotely excited Raman optical activity(ROA)using propagating surface plasmons in chiral Ag nanowires.Using chiral fmoc-glycyl-glycine-OH(FGGO)molecules,we first studied the local surfac...We experimentally investigated remotely excited Raman optical activity(ROA)using propagating surface plasmons in chiral Ag nanowires.Using chiral fmoc-glycyl-glycine-OH(FGGO)molecules,we first studied the local surface plasmon-enhanced ROA.We found that the Raman intensity can be excited by left-and right-circularly polarized lights and that the circular intensity difference(CID)can be significantly enhanced.Second,by selecting vibrational modes with large Raman and ROA intensities that are not influenced by chemical enhancements,we studied remotely excited ROA imaging and the CID of FGGO molecules by propagating a plasmonic waveguide using Ag chiral nanostructures.When laser light was radiated on one of the Ag terminals,the measured CID of the FGG at the other terminal showed little change compared to the local excited CID.Meanwhile,when the laser light was radiated on the Ag nanowires(not on the terminals)and was coupled to the nearby nanoantenna,the CID of the ROA could be manipulated by altering the coupling angle between the Ag nanowires.To directly demonstrate the propagation of ROA along the nanowire and its remote detection,we also measured the remotely excited ROA spectra.Our experimental method has the potential to remotely determine the chirality of molecular structures and the absolute configuration or conformation of a chiral live cell.展开更多
In this paper, we have shown that perfect absorption at terahertz frequencies can be achieved by using a composite structure where graphene is coated on one-dimensional photonic crystal(1 DPC) separated by a dielectri...In this paper, we have shown that perfect absorption at terahertz frequencies can be achieved by using a composite structure where graphene is coated on one-dimensional photonic crystal(1 DPC) separated by a dielectric. Due to the excitation of optical Tamm states(OTSs) at the interface between the graphene and 1 DPC, a strong absorption phenomenon occurs induced by the coupling of the incident light and OTSs. Although the perfect absorption produced by a metal–distributed Bragg reflector structure has been researched extensively, it is generally at a fixed frequency and not tunable. Here, we show that the perfect absorption at terahertz frequency not only can be tuned to different frequencies but also exhibits a high absorption over a wide angle range. In addition,the absorption of the proposed structure is insensitive to the polarization, and multichannel absorption can berealized by controlling the thickness of the top layer.展开更多
We study the sensing properties of an intensity-modulated fiber-optic surface plasmon resonance （SPR） sensor using radially polarized beam （RPB）. Because of the rotational symmetry of fiber and RPB, surface plasmo...We study the sensing properties of an intensity-modulated fiber-optic surface plasmon resonance （SPR） sensor using radially polarized beam （RPB）. Because of the rotational symmetry of fiber and RPB, surface plasmon can be excited more efficiently at the sensor surface, which results in an obvious improvement of the sensitivity. Our experiments demonstrate that the sensitivity in the case of RPB illumination is three times higher than that of linearlv polarized beam illumination.展开更多
Using a metamaterial consisting of metals with subwavelength surface patterning, one can mimic surface plasmon polaritons(SPPs) and achieve surface waves with subwavelength confinement at microwave and terahertz frequ...Using a metamaterial consisting of metals with subwavelength surface patterning, one can mimic surface plasmon polaritons(SPPs) and achieve surface waves with subwavelength confinement at microwave and terahertz frequencies, thus bringing most of the advantages associated with the optical SPPs to lower frequencies. Due to the properties of strong field confinement and high local field intensity, spoof SPPs have demonstrated the improved performance for data transmission and device miniaturization in an intensively integrated environment. The distinctive abilities, such as suppression of transmission loss and bending loss, and increase of signal integrity, make spoof SPPs a promising candidate for future generation of electronic circuits and electromagnetic systems. This article reviews the progress in spoof SPPs with a special focus on their applications in circuits from transmission lines to passive and active devices in microwave and terahertz regimes. The integration of versatile spoof SPP devices on a single platform,which is compatible with established electronic circuits, is also discussed.展开更多
Collective oscillations of free electrons generate plasmons on the surface of a material. A whispering-gallery microcavity effectively confines the light field on its surface based on the total reflection from its int...Collective oscillations of free electrons generate plasmons on the surface of a material. A whispering-gallery microcavity effectively confines the light field on its surface based on the total reflection from its internal wall. When these two kinds of electromagnetic waves meet each other, the stimulated emissions from an individual ZnO microrod were enhanced more than 50-fold and the threshold was reduced after the whispering-gallery microcavity was coated with a monolayer of graphene and A1 nanoparticles. The improvement of the lasing performance was attributed to the synergistic energy coupling of the graphene/A1 surface plasmons with ZnO excitons. The lasing characteristics and the coupling mechanism were investigated systematically.展开更多
The design and synthesis of plasmonic nanoparticles with Raman-active molecules embedded inside them are of significant interest for sensing and imaging applications. However, direct synthesis of such nanostructures w...The design and synthesis of plasmonic nanoparticles with Raman-active molecules embedded inside them are of significant interest for sensing and imaging applications. However, direct synthesis of such nanostructures with controllable shape, size, and plasmonic properties remains extremely challenging. Here we report on the preparation of uniform Au@Ag core/sheU nanorods with controllable Ag shells of 1 to 25 nm in thickness. 1,4-Aminothiophenol （4-ATP） molecules, used as the Raman reporters, were located between the Au core and the Ag shell. Successful embedding of reporter molecules inside the core/shell nanoparticles was confirmed by the absence of selective oxidation of the amino groups, as measured by Raman spectroscopy. The dependence of Raman intensity on the location of the reporter molecules in the inside and outside of the nanorods was studied. The molecules in the interior showed strong and uniform Raman intensity, at least an order of magnitude higher than that of the molecules on the nanoparticle surface. In contrast to the usual surface-functionalized Raman tags, aggregation and clustering of nanoparticles with embedded molecules decreased the surface-enhanced Raman scattering （SERS） signal. The findings from this study provide the basis for a novel detection technique of low analyte concentration utilizing the high SERS response of molecules inside the core/shell metal nanostructures. As an example, we show robust SERS detection of thiram fungicide as low as 10-9 M in solutions.展开更多
The effects of temperature on a surface plasmon studied experimentally and theoretically. SPR resonance （SPR） sensor in Kretschmann configuration are experiments are carried out over a temperature range of 278- 313 ...The effects of temperature on a surface plasmon studied experimentally and theoretically. SPR resonance （SPR） sensor in Kretschmann configuration are experiments are carried out over a temperature range of 278- 313 K in steps of 5 K. A detailed theoretical model is provided to analyze the variation of performance with varying temperature of the sensing environment. The temperature dependence of the properties of the metal, dielectric, and analyte are studied, respectively. The numerical results indicate that the predictions of the theoretical model are well consistent with the experiment data.展开更多
A theoretical investigation on the surface plasmon polariton in a gold cylindrical nanocable is presented. By solving a complete set of Maxwell＇s equations in the nanocable （with a 50 nm radius gold nanocore, 10-300...A theoretical investigation on the surface plasmon polariton in a gold cylindrical nanocable is presented. By solving a complete set of Maxwell＇s equations in the nanocable （with a 50 nm radius gold nanocore, 10-300 nm silica layer, and 30-200nm gold nanocladding）, the dispersion relations on the optical frequency and on the silica thickness are discussed. When the silica thickness varies from 50 to 250 nm, at a fixed waveleltgth, the strong coupling between the gold nanocore and the nanocladding leads to a symmetric-like surface mode and an antisymmetric-like surface mode in the nanocable. The transformation between the surface mode and the waveguide mode in this structure is also investigated. The results will be helpful for understanding the surface waves in the subwavelength structures.展开更多
基金This work was supported by National Nature Science Foundation of China(Grant Nos.91436102,11374353 and 11474141).
文摘The properties of propagating surface plasmon polaritons(SPPs)along one-dimensional metal structures have been investigated for more than 10 years and are now well understood.Because of the high confinement of electromagnetic energy,propagating SPPs have been considered to represent one of the best potential ways to construct next-generation circuits that use light to overcome the speed limit of electronics.Many basic plasmonic components have already been developed.In this review,researches on plasmonic waveguides are reviewed from the perspective of plasmonic circuits.Several circuit components are constructed to demonstrate the basic function of an optical digital circuit.In the end of this review,a prototype for an SPP-based nanochip is proposed,and the problems associated with building such plasmonic circuits are discussed.A plasmonic chip that can be practically applied is expected to become available in the near future.
基金The authors would like to acknowledge financial support from the National Research Foundation,Prime Minister’s Office,Singapore under its Competitive Research Program(CRP Award No.NRF-CRP10-2012-04)the Economic Development Board(SPORE,COY-15-EWI-RCFSA/N197-1)The authors would also like to acknowledge funding provided by the Chinese Nature Science Grant(61138002)and 973 Program of China(No.2013CBA01700).
文摘Light collection efficiency is an important factor that affects the performance of many optical and optoelectronic devices.In these devices,the high reflectivity of interfaces can hinder efficient light collection.To minimize unwanted reflection,anti-reflection surfaces can be fabricated by micro/nanopatterning.In this paper,we investigate the fabrication of broadband anti-reflection Si surfaces by laser micro/nanoprocessing.Laser direct writing is applied to create microstructures on Si surfaces that reduce light reflection by light trapping.In addition,laser interference lithography and metal assisted chemical etching are adopted to fabricate the Si nanowire arrays.The anti-reflection performance is greatly improved by the high aspect ratio subwavelength structures,which create gradients of refractive index from the ambient air to the substrate.Furthermore,by decoration of the Si nanowires with metallic nanoparticles,surface plasmon resonance can be used to further control the broadband reflections,reducing the reflection to below 1.0%across from 300 to 1200 nm.An average reflection of 0.8%is achieved.
基金Work at ORNL was supported by the United States Department of Energy,Basic Energy Sciences,Materials Sciences and Engineering Division.
文摘Light scattering by small particles has a long and interesting history in physics.Nonetheless,it continues to surprise with new insights and applications.This includes new discoveries,such as novel plasmonic effects,as well as exciting theoretical and experimental developments such as optical trapping,anomalous light scattering,optical tweezers,nanospasers,and novel aspects and realizations of Fano resonances.These have led to important new applications,including several ones in the biomedical area and in sensing techniques at the single-molecule level.There are additionally many potential future applications in optical devices and solar energy technologies.Here we review the fundamental aspects of light scattering by small spherical particles,emphasizing the phenomenological treatments and new developments in this field.
基金supported by the National Key R&D Program of China (2017YFA0303800)the National Natural Science Foundation of China (61805277, 11634010, 91950207, 11974283, 11774290)+1 种基金the Fundamental Research Funds for the Central Universities (3102017AX009, 3102019PY002, 3102019JC008)the Natural Science Basic Research Program of Shaanxi (2019JQ-447, 2020JM-130)
文摘Metasurfaces,with extremely exotic capabilities to manipulate electromagnetic(EM)waves,have derived a plethora of advanced metadevices with intriguing functionalities.Tremendous endeavors have been mainly devoted to the static metasurfaces and metadevices,where the functionalities cannot be actively tuned in situ post-fabrication.Due to the in-trinsic advantage of active tunability by external stimulus,graphene has been successively demonstrated as a favorable candidate to empower metasurfaces with remarkably dynamic tunability,and their recent advances are propelling the EM wave manipulations to a new height:from static to dynamic.Here,we review the recent progress on dynamic metasur-faces and metadevices enabled by graphene with the focus on electrically-controlled dynamic manipulation of the EM waves covering the mid-infrared,terahertz,and microwave regimes.The fundamentals of graphene,including basic ma-terial properties and plasmons,are first discussed.Then,graphene-empowered dynamic metasurfaces and met-adevices are divided into two categories,i.e.,metasurfaces with building blocks of structured graphene and hybrid metasurfaces integrated with graphene,and their recent advances in dynamic spectrum manipulation,wavefront shap-ing,polarization control,and frequency conversion in near/far fields and global/local ways are elaborated.In the end,we summarize the progress,outline the remaining challenges,and prospect the potential future developments.
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.
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the National Key R&D Program of China (No. 2018YFF01013003)the Program of Shanghai Pujiang Program, China (No. 17PJD028)+4 种基金the National Natural Science Foundation of China (Nos. 61671302, 61601291, and 61722111)the Shuguang Program supported by the Shanghai Education Development Foundation and Shanghai Municipal Education Commission, China (No. 18SG44)the Key Scientific and Technological Project of Science and Technology Commission of Shanghai Municipality, China (No. 15DZ0500102)the Shanghai Leading Talent, China (No. 2016-019)the Young Yangtse Rive Scholar, China (No. Q2016212).
文摘We give a brief review of the developments in terahertz time-domain spectroscopy(THz-TDS) systems and microcavity components for probing samples in the University of Shanghai for Science and Technology. The broadband terahertz(THz) radiation sources based on GaAs m-i-n diodes have been investigated by applying high electric fields. Then, the free space THz-TDS and fiber-coupled THz-TDS systems produced in our lab and their applications in drug/cancer detection are introduced in detail. To further improve the signal-to-noise ratio(SNR) and enhance sensitivity, we introduce three general micro-cavity approaches to achieve tiny-volume sample detection, summarizing our previous results about their characteristics, performance, and potential applications.
基金supported by the National Natural Science Foundation of China(No.60678047)the Science Foundation of Tianjin(No.05YFJZJC02300)
文摘We investigated the effect of photodynamic therapy （PDT） with hematoporphyrin monomethyl ether （HMME） on the viability of Streptococcus mutans （S. mutans） cells on biofilms in vitro. Streptococcus mutans is the primary etiological agent of human dental caries. Since dental caries are localized infections, such plaque-related diseases would be well suited to PDT. The diode laser used in this study had the wavelength of 635 nm, whose output power was 10 mW and the energy density was 12.74 J/cm^2. HMME was used as photosensitizer. Samples were prepared and divided into five groups： （1） HMME; （2） Laser; （3） HMME＋Laser; （4） Control group （＋） with chlorhexidine; and （5） Control group （-） with sterile physiological saline. Inoculum of S. mutans incubated with HMME also examined with fluorescence microscopy. PDT exhibited a significantly （P 〈 0.05） increased antimicrobial potential compared with 20 μm/mL HMME only, laser only, 0.05% chlorhexidine, and 0.9% sterile physiological saline, which reduced the S. mutans of the biofilm most effectively. Laser and 0.05% chlorhexidine were caused reduction in the viable counts of S. mutans significantly different （P 〈 0.05） also, but these two test treatments did not statistically differ from each other. HMME group did not statistically differ with negative control group. Fluorescence microscopy indicated that HMME localized primarily in the S. mutans of the biofilm. It was demonstrated that HMME-mediated PDT was efficient at killing S. mutans of biofilms and a useful approach in the treatment of dental plaque-related diseases.
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.
基金supported by DARPA/MARCO under the Interconnect Focus Center and by AFOSR grant FA 9550-04-1-0437.
文摘We review some of the recent advances in the development of subwavelength plasmonic devices for manipulating light at the nanoseale, drawing examples from our own work in metal-dielectric-metal （MDM） plasmonic waveguide devices. We introduce bends, splitters, and mode converters for MDM waveguides with no additional loss. We also demonstrate that optical gain provides a mechanism for on/off switching in MDM plasmonic waveguides. Highly efficient compact couplers between dielectric waveguides and MDM waveguides are also introduced.
基金partially supported by the US National Science Foundation
文摘We present a review of terahertz plasmonic metamaterial devices that have functionalities and applications ranging from sensing, enhanced electromagnetic fields, and near field manipulation. Metamaterials allow the properties of light propagation to be manipulated at will by using a combination of appropriately designed geometry and suitable materials at the unit cell level. In this review, we first discuss the sensing aspect of a planar plasmonic metamaterial and how to overcome its limitations. Conventional symmetric metamaterials are limited by their low Q factor, thus we probed the symmetry broken plasmonic metama- terial structures in which the interference between a broad continuum mode and a narrow localized mode leads to the excitation of the sharp Fano resonances. We also discuss the near field mediated excitation of dark plasmonic modes in metamaterials that is caused by a strong coupling from the bright mode res- onator. The near field coupling between the dark and bright mode resonances leads to classical analogue of electromagnetically induced transparency in plasmonic systems. Finally, we discuss active switching in terahertz metamateriMs based on high temperature superconductors that holds the promise of reducing the resistive losses in these systems, though it fails to suppress the radiation loss in plasmonic metamaterial at terahertz frequencies.
基金This work was supported by the National Natural Science Foundation of China(11374353 and 11274149)the Program of Shenyang Key Laboratory of Optoelectronic Materials and Technology(F12-254-1-00).
文摘We experimentally investigated remotely excited Raman optical activity(ROA)using propagating surface plasmons in chiral Ag nanowires.Using chiral fmoc-glycyl-glycine-OH(FGGO)molecules,we first studied the local surface plasmon-enhanced ROA.We found that the Raman intensity can be excited by left-and right-circularly polarized lights and that the circular intensity difference(CID)can be significantly enhanced.Second,by selecting vibrational modes with large Raman and ROA intensities that are not influenced by chemical enhancements,we studied remotely excited ROA imaging and the CID of FGGO molecules by propagating a plasmonic waveguide using Ag chiral nanostructures.When laser light was radiated on one of the Ag terminals,the measured CID of the FGG at the other terminal showed little change compared to the local excited CID.Meanwhile,when the laser light was radiated on the Ag nanowires(not on the terminals)and was coupled to the nearby nanoantenna,the CID of the ROA could be manipulated by altering the coupling angle between the Ag nanowires.To directly demonstrate the propagation of ROA along the nanowire and its remote detection,we also measured the remotely excited ROA spectra.Our experimental method has the potential to remotely determine the chirality of molecular structures and the absolute configuration or conformation of a chiral live cell.
基金National Natural Science Foundation of China(NSFC)(51806001,61490713,61505111)Natural Science Foundation of Guangdong Province(2015A030313549)+3 种基金China Postdoctoral Science Foundation(2016M602509)Science and Technology Planning Project of Guangdong Province(2016B050501005)Science and Technology Project of Shenzhen(JCYJ20150324141711667)Natural Science Foundation of SZU(827-000051,827-000052,827-000059)
文摘In this paper, we have shown that perfect absorption at terahertz frequencies can be achieved by using a composite structure where graphene is coated on one-dimensional photonic crystal(1 DPC) separated by a dielectric. Due to the excitation of optical Tamm states(OTSs) at the interface between the graphene and 1 DPC, a strong absorption phenomenon occurs induced by the coupling of the incident light and OTSs. Although the perfect absorption produced by a metal–distributed Bragg reflector structure has been researched extensively, it is generally at a fixed frequency and not tunable. Here, we show that the perfect absorption at terahertz frequency not only can be tuned to different frequencies but also exhibits a high absorption over a wide angle range. In addition,the absorption of the proposed structure is insensitive to the polarization, and multichannel absorption can berealized by controlling the thickness of the top layer.
基金supported by the National Basic Research Program of China (No.2006cb302905)the Key Program of National Natural Science Foundation of China (No.60736037)+1 种基金the National Natural Science Foundation of China (No.10704070)P.Wang was also supported by the Science and Technological Fund of Anhui Province for Outstanding Youth (No.08040106805)
文摘We study the sensing properties of an intensity-modulated fiber-optic surface plasmon resonance （SPR） sensor using radially polarized beam （RPB）. Because of the rotational symmetry of fiber and RPB, surface plasmon can be excited more efficiently at the sensor surface, which results in an obvious improvement of the sensitivity. Our experiments demonstrate that the sensitivity in the case of RPB illumination is three times higher than that of linearlv polarized beam illumination.
基金supported in part from the National Natural Science Foundation of China(61871127,61735010,61631007,61571117,61501112,61501117,61522106,61722106,61701107,61701246 and 61701108)the Fundamental Research Funds for the Central Universities(2242018R30001)+1 种基金National Key Research and Development Program of China(2017YFA0700201,2017YFA0700202,and 2017YFA0700203)the 111 Project(111-2-05)
文摘Using a metamaterial consisting of metals with subwavelength surface patterning, one can mimic surface plasmon polaritons(SPPs) and achieve surface waves with subwavelength confinement at microwave and terahertz frequencies, thus bringing most of the advantages associated with the optical SPPs to lower frequencies. Due to the properties of strong field confinement and high local field intensity, spoof SPPs have demonstrated the improved performance for data transmission and device miniaturization in an intensively integrated environment. The distinctive abilities, such as suppression of transmission loss and bending loss, and increase of signal integrity, make spoof SPPs a promising candidate for future generation of electronic circuits and electromagnetic systems. This article reviews the progress in spoof SPPs with a special focus on their applications in circuits from transmission lines to passive and active devices in microwave and terahertz regimes. The integration of versatile spoof SPP devices on a single platform,which is compatible with established electronic circuits, is also discussed.
文摘Collective oscillations of free electrons generate plasmons on the surface of a material. A whispering-gallery microcavity effectively confines the light field on its surface based on the total reflection from its internal wall. When these two kinds of electromagnetic waves meet each other, the stimulated emissions from an individual ZnO microrod were enhanced more than 50-fold and the threshold was reduced after the whispering-gallery microcavity was coated with a monolayer of graphene and A1 nanoparticles. The improvement of the lasing performance was attributed to the synergistic energy coupling of the graphene/A1 surface plasmons with ZnO excitons. The lasing characteristics and the coupling mechanism were investigated systematically.
文摘The design and synthesis of plasmonic nanoparticles with Raman-active molecules embedded inside them are of significant interest for sensing and imaging applications. However, direct synthesis of such nanostructures with controllable shape, size, and plasmonic properties remains extremely challenging. Here we report on the preparation of uniform Au@Ag core/sheU nanorods with controllable Ag shells of 1 to 25 nm in thickness. 1,4-Aminothiophenol （4-ATP） molecules, used as the Raman reporters, were located between the Au core and the Ag shell. Successful embedding of reporter molecules inside the core/shell nanoparticles was confirmed by the absence of selective oxidation of the amino groups, as measured by Raman spectroscopy. The dependence of Raman intensity on the location of the reporter molecules in the inside and outside of the nanorods was studied. The molecules in the interior showed strong and uniform Raman intensity, at least an order of magnitude higher than that of the molecules on the nanoparticle surface. In contrast to the usual surface-functionalized Raman tags, aggregation and clustering of nanoparticles with embedded molecules decreased the surface-enhanced Raman scattering （SERS） signal. The findings from this study provide the basis for a novel detection technique of low analyte concentration utilizing the high SERS response of molecules inside the core/shell metal nanostructures. As an example, we show robust SERS detection of thiram fungicide as low as 10-9 M in solutions.
基金supported by the National "973" Program of China (No.2006CB302905)the Key Program of National Natural Science Foundation of China (No.60736037)+2 种基金the National Natural Science Foundation of China (No.10704070)the National "863" Program of China (No.2007AA06Z420)the Science and Technological Fund of Anhui Province for Outstanding Youth(No.08040106805)
文摘The effects of temperature on a surface plasmon studied experimentally and theoretically. SPR resonance （SPR） sensor in Kretschmann configuration are experiments are carried out over a temperature range of 278- 313 K in steps of 5 K. A detailed theoretical model is provided to analyze the variation of performance with varying temperature of the sensing environment. The temperature dependence of the properties of the metal, dielectric, and analyte are studied, respectively. The numerical results indicate that the predictions of the theoretical model are well consistent with the experiment data.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10674009, 10521002 and 10434020)the National Key Development Program for Basic Research of China (Grant No 2007CB307001)
文摘A theoretical investigation on the surface plasmon polariton in a gold cylindrical nanocable is presented. By solving a complete set of Maxwell＇s equations in the nanocable （with a 50 nm radius gold nanocore, 10-300 nm silica layer, and 30-200nm gold nanocladding）, the dispersion relations on the optical frequency and on the silica thickness are discussed. When the silica thickness varies from 50 to 250 nm, at a fixed waveleltgth, the strong coupling between the gold nanocore and the nanocladding leads to a symmetric-like surface mode and an antisymmetric-like surface mode in the nanocable. The transformation between the surface mode and the waveguide mode in this structure is also investigated. The results will be helpful for understanding the surface waves in the subwavelength structures.
