Manipulating directional electromagnetic scattering plays a crucial role in the realization of exotic optical phenomenon.Here,we show that the spoof plasmonic structure is able to achieve the switching of directional ...Manipulating directional electromagnetic scattering plays a crucial role in the realization of exotic optical phenomenon.Here,we show that the spoof plasmonic structure is able to achieve the switching of directional scattering direction on a subwavelength scale by inserting a perfect electric conductor(PEC)cylinder into the hollow of the spoof plasmonic structure.Based on the modal analysis,it is found that the electromagnetic response of the core-shell structure not only is well excited,but also exhibits the directional scattering by interference between the electric and magnetic dipolar resonances.We also discuss the influence of PEC cylinder radius on the performance of the directional scattering.Finally,the active tunable directional scattering is realized by switching between the two states.This work provides a feasible pathway to the subwavelength manipulation of electromagnetic wave.Moreover,it offers a simple method to switch the directional scattering direction.The proposed design approach can be easily applied to digital electromagnetic wave communication and associated applications.展开更多
A highly stretchable plasmonic structure composed of a monolayer array of metal-capped colloidal spheres on an elastomeric substrate has been fabricated using simple and inexpensive self-assembly and transfer-printing...A highly stretchable plasmonic structure composed of a monolayer array of metal-capped colloidal spheres on an elastomeric substrate has been fabricated using simple and inexpensive self-assembly and transfer-printing techniques.This composite structure supports coupled surface plasmons whose wavelengths are sensitive to the arrangement of the metal-capped colloidal spheres.Upon stretching,the lattice of metal-capped colloidal spheres will be deformed,leading to a large wavelength shift of surface plasmon resonances and simultaneously an obvious color change.This stretchable plasmonic structure offers a promising approach to tune surface plasmon resonances and might be exploited in realizing flexible plasmonic devices with tunability of mechanical strain.展开更多
We theoretically propose blue-detuned optical trapping for neutral atoms via strong near-field interfacing in a plasmonic nanohole array. The optical field at resonance forms a nanoscale-trap potential with an FWHM of...We theoretically propose blue-detuned optical trapping for neutral atoms via strong near-field interfacing in a plasmonic nanohole array. The optical field at resonance forms a nanoscale-trap potential with an FWHM of 200 nm and about ～370 nm away from the nanohole; thus, a stable 3 D atom trapping independent of the surface potential is demonstrated. The effective trap depth is more than 1 m K when the optical power of trapping light is only about 0.5 m W, while the atom scattering rate is merely about 3.31 s^(-1), and the trap lifetime is about 800 s.This compact plasmonic structure provides high uniformity of trap depths and a two-layer array of atom nanotraps, which should have important applications in the manipulation of cold atoms and collective resonance fluorescence.展开更多
A combined structure with the unit cell consisting of four sub-units with 90° rotation in turn is designed. Each of sub-units is composed of two gold rods in transverse arrangement and one gold rod in longitudina...A combined structure with the unit cell consisting of four sub-units with 90° rotation in turn is designed. Each of sub-units is composed of two gold rods in transverse arrangement and one gold rod in longitudinal arrangement. Simulating electromagnetic responses of the structure, we verify that the structure exhibits the double Fano resonances, which originate from the coupling between magnetic quadrupoles and electric dipoles and the coupling between electric quadrupoles and electric dipoles. Simulation results also demonstrate that the structure is polarization-insensitive and shows an analogue of electromagnetically induced transparency at the two Fano resonances. Such a plasmonic structure has potential applications in photoelectric elements.展开更多
The modulation of resonance features in microcavities is important to applications in nanophotonics.Based on the asymmetric whispering-gallery modes(WGMs)in a plasmonic resonator,we theoretically studied the mode evol...The modulation of resonance features in microcavities is important to applications in nanophotonics.Based on the asymmetric whispering-gallery modes(WGMs)in a plasmonic resonator,we theoretically studied the mode evolution in an asymmetric WGM plasmonic system.Exploiting the gap or nano-scatter in the plasmonic ring cavity,the symmetry of the system will be broken and the standing wave in the cavity will be tunable.Based on this asymmetric structure,the output coupling rate between the two cavity modes can also be tuned.Moreover,the proposed method could further be applied for sensing and detecting the position of defects in a WGM system.展开更多
High-sensitivity photodetection is at the heart of many optoelectronic applications,including spectroscopy,imaging,surveillance,remote sensing and medical diagnostics.Achieving the highest possible sensitivity for a g...High-sensitivity photodetection is at the heart of many optoelectronic applications,including spectroscopy,imaging,surveillance,remote sensing and medical diagnostics.Achieving the highest possible sensitivity for a given photodetector technology requires the development of ultra-small-footprint detectors,as the noise sources scale with the area of the detector.This must be accomplished while sacrificing neither the optically active area of the detector nor its responsivity.Currently,such designs are based on diffraction-limited approaches using optical lenses.Here,we employ a plasmonic flat-lens bull’s eye structure(BES)to concentrate and focus light into a nanoscale colloidal quantum dot(CQD)photodetector.The plasmonic lenses function as nanofocusing resonant structures that simultaneously offer color selectivity and enhanced sensitivity.Herein,we demonstrate the first CQD photodetector with a nanoscale footprint,the optically active area of which is determined by the BES;this detector represents an exciting opportunity for high-sensitivity sensing.展开更多
The self-formation of periodic subwavelength ripples by linear polarized femtosecond laser scanning planar and non-planar tungsten targets on the employed laser wavelength, scanning speed, and energy fluence are exami...The self-formation of periodic subwavelength ripples by linear polarized femtosecond laser scanning planar and non-planar tungsten targets on the employed laser wavelength, scanning speed, and energy fluence are examined systematically. The results show that, for a certain laser wavelength, the scanning conditions have no obvious effect to the morphological features of grating structures in the threshold range of laser fluence. The spatial structured period of gratings can be self-consistently interpreted by recently presented physical model of surface two-plasmon resonance. The subwavelength structures on cylindrical surface would be a good method to realize unique surface functions on complex surface of micro-devices.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11904008)the Natural Science Foundation of Anhui Province,China(Grant No.1908085QA21)the China Postdoctoral Science Foundation(Grant No.2019M662132)。
文摘Manipulating directional electromagnetic scattering plays a crucial role in the realization of exotic optical phenomenon.Here,we show that the spoof plasmonic structure is able to achieve the switching of directional scattering direction on a subwavelength scale by inserting a perfect electric conductor(PEC)cylinder into the hollow of the spoof plasmonic structure.Based on the modal analysis,it is found that the electromagnetic response of the core-shell structure not only is well excited,but also exhibits the directional scattering by interference between the electric and magnetic dipolar resonances.We also discuss the influence of PEC cylinder radius on the performance of the directional scattering.Finally,the active tunable directional scattering is realized by switching between the two states.This work provides a feasible pathway to the subwavelength manipulation of electromagnetic wave.Moreover,it offers a simple method to switch the directional scattering direction.The proposed design approach can be easily applied to digital electromagnetic wave communication and associated applications.
基金This work was supported by the National Program on Key Basic Research Project(973 Program)(Grant Nos.2007CB613200 and 2006CB921700)The research of J.Z.and X.H.L.is further supported by the National Natural Science Foundation of China(NSFC)and the Shanghai Science and Technology Commission.
文摘A highly stretchable plasmonic structure composed of a monolayer array of metal-capped colloidal spheres on an elastomeric substrate has been fabricated using simple and inexpensive self-assembly and transfer-printing techniques.This composite structure supports coupled surface plasmons whose wavelengths are sensitive to the arrangement of the metal-capped colloidal spheres.Upon stretching,the lattice of metal-capped colloidal spheres will be deformed,leading to a large wavelength shift of surface plasmon resonances and simultaneously an obvious color change.This stretchable plasmonic structure offers a promising approach to tune surface plasmon resonances and might be exploited in realizing flexible plasmonic devices with tunability of mechanical strain.
基金National Key Basic Research Program(2013CB328700)National Natural Science Foundation of China(NSFC)(11525414,11374025,91221304)
文摘We theoretically propose blue-detuned optical trapping for neutral atoms via strong near-field interfacing in a plasmonic nanohole array. The optical field at resonance forms a nanoscale-trap potential with an FWHM of 200 nm and about ～370 nm away from the nanohole; thus, a stable 3 D atom trapping independent of the surface potential is demonstrated. The effective trap depth is more than 1 m K when the optical power of trapping light is only about 0.5 m W, while the atom scattering rate is merely about 3.31 s^(-1), and the trap lifetime is about 800 s.This compact plasmonic structure provides high uniformity of trap depths and a two-layer array of atom nanotraps, which should have important applications in the manipulation of cold atoms and collective resonance fluorescence.
基金Supported by the National Innovative Projects for College Students under Grant No 201310320025the National Natural Science Foundation of China under Grant Nos 61401182 and 61372057the Priority Academic Program Development of Jiangsu Higher Education Institutions of China
文摘A combined structure with the unit cell consisting of four sub-units with 90° rotation in turn is designed. Each of sub-units is composed of two gold rods in transverse arrangement and one gold rod in longitudinal arrangement. Simulating electromagnetic responses of the structure, we verify that the structure exhibits the double Fano resonances, which originate from the coupling between magnetic quadrupoles and electric dipoles and the coupling between electric quadrupoles and electric dipoles. Simulation results also demonstrate that the structure is polarization-insensitive and shows an analogue of electromagnetically induced transparency at the two Fano resonances. Such a plasmonic structure has potential applications in photoelectric elements.
基金National Natural Science Foundation of China(NSFC)(61622103,61471050,61671083,11404031)Fok Ying-Tong Education Foundation for Young Teachers in the Higher Education Institutions of China(151063)Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics,Tsinghua University(KF201610)
文摘The modulation of resonance features in microcavities is important to applications in nanophotonics.Based on the asymmetric whispering-gallery modes(WGMs)in a plasmonic resonator,we theoretically studied the mode evolution in an asymmetric WGM plasmonic system.Exploiting the gap or nano-scatter in the plasmonic ring cavity,the symmetry of the system will be broken and the standing wave in the cavity will be tunable.Based on this asymmetric structure,the output coupling rate between the two cavity modes can also be tuned.Moreover,the proposed method could further be applied for sensing and detecting the position of defects in a WGM system.
基金We thank M Castro-Lo´pez for assistance with the transmission measurements,J Osmond and F Beck for assistance during clean-room fabrication,and M Lundeberg for wire bonding our samples.We acknowledge funding from the European Commission’s Seventh Framework Programme for Research under contract PIEF-GA-2011-298596 and from Fundacio Privada Cellex Barcelona.We are also grateful to the Ministerio de Ciencia e Innovacion for financial support under contract number TEC2011-24744.GK acknowledges MICINN for a Ramon y Cajal Fellowship.
文摘High-sensitivity photodetection is at the heart of many optoelectronic applications,including spectroscopy,imaging,surveillance,remote sensing and medical diagnostics.Achieving the highest possible sensitivity for a given photodetector technology requires the development of ultra-small-footprint detectors,as the noise sources scale with the area of the detector.This must be accomplished while sacrificing neither the optically active area of the detector nor its responsivity.Currently,such designs are based on diffraction-limited approaches using optical lenses.Here,we employ a plasmonic flat-lens bull’s eye structure(BES)to concentrate and focus light into a nanoscale colloidal quantum dot(CQD)photodetector.The plasmonic lenses function as nanofocusing resonant structures that simultaneously offer color selectivity and enhanced sensitivity.Herein,we demonstrate the first CQD photodetector with a nanoscale footprint,the optically active area of which is determined by the BES;this detector represents an exciting opportunity for high-sensitivity sensing.
基金supported by the National Natural Science Foundation of China under Grant No.51275012
文摘The self-formation of periodic subwavelength ripples by linear polarized femtosecond laser scanning planar and non-planar tungsten targets on the employed laser wavelength, scanning speed, and energy fluence are examined systematically. The results show that, for a certain laser wavelength, the scanning conditions have no obvious effect to the morphological features of grating structures in the threshold range of laser fluence. The spatial structured period of gratings can be self-consistently interpreted by recently presented physical model of surface two-plasmon resonance. The subwavelength structures on cylindrical surface would be a good method to realize unique surface functions on complex surface of micro-devices.
