Surface enhanced Raman scattering(SERS)is an efficient technique to detect low concentration molecules.In this work,periodical silicon nanowires(Si NWs)integrated with metal-insulator-metal(MIM)layers are employed as ...Surface enhanced Raman scattering(SERS)is an efficient technique to detect low concentration molecules.In this work,periodical silicon nanowires(Si NWs)integrated with metal-insulator-metal(MIM)layers are employed as SERS substrates.Laser interference lithography(LIL)combined with reactive ion etching(RIE)is used to fabricate large-area periodic nanostructures,followed by decorating the MIM layers.Compared to MIM disks array on Si surface,the SERS enhancement factor(EF)of the MIM structures on the Si NWs array can be increased up to 5 times,which is attributed to the enhanced electric field at the boundary of the MIM disks.Furthermore,high density of nanoparticles and nanogaps serving as hot spots on sidewall surfaces also contribute to the enhanced SERS signals.Via changing the thickness of the insulator layer,the plasmonic resonance can be tuned,which provides a new localized surface plasmon resonance(LSPR)characteristic for SERS applications.展开更多
A plasmonic waveguide coupled system that is composed of a square ring cavity and a metal-insulator-metal （MIM） waveguide with two silver baffles is proposed. The transmission and reflection properties of the propos...A plasmonic waveguide coupled system that is composed of a square ring cavity and a metal-insulator-metal （MIM） waveguide with two silver baffles is proposed. The transmission and reflection properties of the proposed plasmonic system are investigated numerically using the finite element method. The normalized Hz field distributions are calculated to analyze the transmission mode in the plasmonic system. The extreme destructive interference between light mode and dark mode causes plasmonically induced reflection （PIR） window in the transmission spectrum. The PIR window is fitted using the coupled mode theory. The analytical result agrees with the simulation result approximately. In addition, the PIR window can be controlled by adjusting structural parameters and filling different dielectric into the MIM waveguide and the square ring cavity. The results provide a new approach to designing plasmonic devices.展开更多
To increase the absorption in a thin layer of absorbing material （amorphous silicon, a-Si）, a light trapping design is presented. The designed structure incorporates periodic metal-insulator-metal waveguides to enha...To increase the absorption in a thin layer of absorbing material （amorphous silicon, a-Si）, a light trapping design is presented. The designed structure incorporates periodic metal-insulator-metal waveguides to enhance the optical path length of light within the solar cells. The new design can result in broadband optical absorption enhancement not only for transverse magnetic （TM）-polarized light, but also for transverse electric （TE）-polarized light. No plasmonic modes can be excited in TE-polarization, but because of the coupling into the a-Si planar waveguide guiding modes and the diffraction of light by the bottom periodic structures into higher diffraction orders, the total absorption in the active region is also increased. The results from rigorous coupled wave analysis show that the overall optical absorption in the active layer can be greatly enhanced by up to 40%. The designed structures presented in this paper can be integrated with back contact technology to potentially produce high-efficiency thin-film solar cell devices.展开更多
A metal-insulator-metal(MIM)-based arc-shaped resonator coupled with a rectangular stub(MARS) structure is proposed. This structure can generate two tunable Fano resonances originating from two different mechanisms. T...A metal-insulator-metal(MIM)-based arc-shaped resonator coupled with a rectangular stub(MARS) structure is proposed. This structure can generate two tunable Fano resonances originating from two different mechanisms. The structure has the advantage of being sensitive to the refractive index, and this feature makes it favorable for application in various microsensors. The relationship between the structural parameters and Fano resonance is researched using the finite element method(FEM) based on the software COMSOL Multiphysics 5.4. The simulation reveals that the sensitivity reaches1900 nm/refractive index unit(RIU), and the figure of merit(FOM) is 23.75.展开更多
A plasmonic Mach-Zehnder interferometric sensor based on a semicircular aperture-slit nanostructure patterned on a metal-insulator-metal film is proposed and demonstrated by finite difference time domain（FDTD） simul...A plasmonic Mach-Zehnder interferometric sensor based on a semicircular aperture-slit nanostructure patterned on a metal-insulator-metal film is proposed and demonstrated by finite difference time domain（FDTD） simulation. Due to the interference between two different surface plasmon polariton modes in this design, the transmission spectra exhibit oscillation behaviors in a broad bandwidth, and can be readily tailored by changing the SPP path length and core layer thickness. Based on this principle, the characteristics of refractive index sensing are also demonstrated by simulation. This structure is illuminated with a collimated light source from the back side to avoid impacts on the interference. Meanwhile,these results show that the proposed structure is promising for portable, efficient, and sensitive biosensing applications.展开更多
Developing a convenient method that can be routinely applied for ascertaining proportions of different vegetable oils employed in commercial blended edible oils remains a significant challenge.We address this issue by...Developing a convenient method that can be routinely applied for ascertaining proportions of different vegetable oils employed in commercial blended edible oils remains a significant challenge.We address this issue by proposing a novel method for detecting volume fraction of different oils based on the fact that these oils are optically transparent and have slightly different indices of refraction at a given temperature and wavelength.Accordingly,we develop a highly sensitive sensor for measuring the index of refraction of oil blends based on Fano resonance spectra obtained using a metal-insulatormetal(MIM)waveguide structure comprising a gapped straight waveguide coupled with two L-shaped resonators.The index of refraction sensitivity and figure of merit of the structure are calculated based on modeling using the finite element method,and the waveguide structure is accordingly optimized by adjusting the different geometric parameters to achieve a high-quality Fano resonance spectrum.The optimized structure achieves an ultra-high refractive index sensitivity of 770 nm/RIU in terms of a refractive index unit(RIU)of 1.Moreover,a highly stable linear relationship is obtained between the refractive index of mixed edible oils and the resonance wavelength.Experimental results demonstrate that the proposed structure can detect slight changes in the volume fractions of the components in blended oils.展开更多
The chiral feature of an optical field can be evaluated by the parameter of g-factor enhancement,which is helpful to enhance chiroptic signals from a chiral dipole.In this work,the superchiral spot has been theoretica...The chiral feature of an optical field can be evaluated by the parameter of g-factor enhancement,which is helpful to enhance chiroptic signals from a chiral dipole.In this work,the superchiral spot has been theoretically proposed in metal-insulator-metal waveguides.The g-factor enhancement of the superchiral spot can be enhanced by 67-fold more than that of circularly polarized light,and the spot is confined in the deep wavelength scale along each spatial dimension.Moreover,the position of the superchiral spot can be tuned by manipulating the incident field.The tunable superchiral spot may find applications in chiral imaging and sensing.展开更多
A fabrication process based on the self-assembling polystyrene spheres is proposed to obtain hole arrayed metal-insulator-metal （HA-MIM） structure for surface enhanced Raman scattering （SERS）. The localized field ...A fabrication process based on the self-assembling polystyrene spheres is proposed to obtain hole arrayed metal-insulator-metal （HA-MIM） structure for surface enhanced Raman scattering （SERS）. The localized field enhancement aroused by the gap resonance in the HA-MIM structure is analyzed by finite-different time domain （FDTD） method. With reference to the theory result, the structure is experimentally fabricated and the Raman scattering spectrum of rhodamine 6G （R6G） is measured by a miniaturized Raman spectrometer. The results shows that the enhancement factor is 3.85 times higher than the control sample with single layered metal hole array. The fabrication process to obtain the HA-MIM SERS substrate is reproducible, fast, large area and low cost.展开更多
We propose a design for efficient end-fire coupling of surface plasmon polaritons in a metal-insulator-metal(MIM) waveguide with an optical fiber as part of a simple photoplastic connector. The design was analyzed and...We propose a design for efficient end-fire coupling of surface plasmon polaritons in a metal-insulator-metal(MIM) waveguide with an optical fiber as part of a simple photoplastic connector. The design was analyzed and optimized using the three-dimensional finite-difference time-domain method. The calculated excitation efficiency coefficient of the waveguide is 83.7%(-0.77 dB) at a wavelength of 405 nm. This design enables simple connection of an optical fiber to a MIM waveguide and highly efficient local excitation of the waveguide.Moreover, the length of the metallic elements of the waveguide, and thus the dissipative losses, can be reduced.The proposed design may be useful in plasmonic-type waveguide applications such as near-field investigation of live cells and other objects with super-resolution.展开更多
In this paper,a Bragg reflector is proposed by placing periodic metallic gratings in the center of a metal-insulator-metal(MIM)waveguide.According to the effective refractive index modulation caused by different waveg...In this paper,a Bragg reflector is proposed by placing periodic metallic gratings in the center of a metal-insulator-metal(MIM)waveguide.According to the effective refractive index modulation caused by different waveguide widths in a period,a reflection channel with a large bandwidth is firstly achieved.Besides,the Mach-Zehnder interference(MZI)effect arises by shifting the gratings away from the waveguide center.Owing to different optical paths with unequal indices on both sides of the grating,a narrow MZI band gap will be obtained.It is interesting to find out that the Bragg reflector and Mach-Zehnder interferometer are immune to each other,and their wavelengths can be manipulated by the period and the grating length,respectively.Additionally,we can obtain three MZI channels and one Bragg reflection channel by integrating three different gratings into a large period.The performances are investigated by finite-difference time-domain(FDTD)simulations.In the index range of 1.33–1.36,the maximum sensitivity for the structure is as high as 1500 nm/RIU,and it is believed that this proposed structure can find widely applications in the chip-scale optical communication and sensing areas.展开更多
Metal-insulator-metal （MIM） capacitors with atomic-layer-deposited Al2O3 dielectric and reactively sputtered TaN electrodes in application to radio frequency integrated circuits have been characterized electrically....Metal-insulator-metal （MIM） capacitors with atomic-layer-deposited Al2O3 dielectric and reactively sputtered TaN electrodes in application to radio frequency integrated circuits have been characterized electrically. The capacitors exhibit a high density of about 6.05 fF/μm^2, a small leakage current of 4.8 × 10^-8 A/cm^2 at 3 V, a high breakdown electric field of 8.61 MV/cm as well as acceptable voltage coefficients of capacitance （VCCs） of 795 ppm/V2 and 268ppm/V at 1 MHz. The observed properties should be attributed to high-quality Al2O3 film and chemically stable TaN electrodes. Further, a logarithmically linear relationship between quadratic VCC and frequency is observed due to the change of relaxation time with carrier mobility in the dielectric. The conduction mechanism in the high field ranges is dominated by the Poole-Frenkel emission, and the leakage current in the low field ranges is likely to be associated with trap-assisted tunnelling. Meanwhile, the Al2O3 dielectric presents charge trapping under low voltage stresses, and defect generation under high voltage stresses, and it has a hard-breakdown performance.展开更多
Based on Fabry model and finite-different time-domain(FDTD) method, the plasmonic structure composed of a metal-insulator-metal(MIM) bus waveguide and a side-coupled resonator was investigated. It is found that the tr...Based on Fabry model and finite-different time-domain(FDTD) method, the plasmonic structure composed of a metal-insulator-metal(MIM) bus waveguide and a side-coupled resonator was investigated. It is found that the transmission features can be regulated by the cavity width and coupling distance. Electromagnetically induced transparency(EIT)-like transmission can be excited by adding an identical resonator on the pre-existing structure. Combining the foregoing theoretical analysis with coupled mode theory(CMT), the formation process of the EIT-like transmission was detailedly analyzed. EIT-like transmission can also be excited in plasmonic structure with two detuned resonators. By altering the structure parameters, the transparency window can be purposefully modulated. With the merits of compact structure and simplicity in fabrication, the proposed structures may have a broad prospect of applications in highly integrated optical circuits.展开更多
We propose and analyze a submicron stub-assisted ultrafast all-optical plasmonic switch based on nonlinear MIM waveguide. It is constructed by two silicon stub filters sandwiched by silver cladding. The signal wavelen...We propose and analyze a submicron stub-assisted ultrafast all-optical plasmonic switch based on nonlinear MIM waveguide. It is constructed by two silicon stub filters sandwiched by silver cladding. The signal wavelength is assumed to be 1550 nm. The simulation results show a ?14.66 dB extinction ratio. Downscaling the silicon waveguide in MIM structure leads to enhancement of the effective Kerr nonlinearity due to tight mode confinement. Also, using O+ ions implanted into silicon, the switching time less than 10 ps and a delay time less than 8 fs are achieved. The overall length of the switch is 550 nm.展开更多
A novel hybrid structure with high responsivity and efficiency is proposed based on an L-shaped frame nano-antenna(LSFNA)array for solar energy harvesting application.So,two types of LSFNAs are designed and optimized ...A novel hybrid structure with high responsivity and efficiency is proposed based on an L-shaped frame nano-antenna(LSFNA)array for solar energy harvesting application.So,two types of LSFNAs are designed and optimized to enhance the harvesting characteristics of traditional simple electric dipole nano-antenna(SEDNA).The LSFNA geometrical dimensions are optimized to have the best values for the required input impedance at three resonance wavelengths ofλ_(res)=10μm,15μm,and 20μm.Then the LSFNAs with three different sizes are modeled like a planar spiral-shaped array(PSSA).Also,a fractal bowtie nano-antenna is connected with the PSSA in the array gap.This proposed hybrid structure consists of two main elements:(I)Three different sizes of the LSFNAs with two different material types are designed based on the thin-film metal-insulator-metal diodes that are a proper method for infrared energy harvesting.(Ⅱ)The PSSA gap is designed based on the electron field emission proposed by the Fowler-Nordheim theory for the array rectification.Finally,the proposed device is analyzed.The results show that the PSSA not only has an averaged 3-time enhancement in the harvesting characteristics(such as return loss,harvesting efficiency,etc.)than the previously proposed structures but also is a multi-resonance wide-band device.Furthermore,the proposed antenna takes up less space in the electronic circuit and has an easy implementation process.展开更多
In this work, a development of a method of a thin insulating film vertical edge visualization of metal-insulator-metal （MIM） memory cells with atomic force microscopy （AFM） using a modified Omicron UHV AFM/STM mic...In this work, a development of a method of a thin insulating film vertical edge visualization of metal-insulator-metal （MIM） memory cells with atomic force microscopy （AFM） using a modified Omicron UHV AFM/STM microscope was performed. This included a development of a technique of the AFM visualization of segments of a vertical edge of thin insulator SiO2 film structures on a conductive substrate, a comparison of AFM topography and current profilograms for the edge profiles, and an Omicron microscope custom upgrade. The latter allowed us to perform the AFM probe positioning to any specific area of the sample in the scanning plane by two coordinates with an order of precision of 1 micrometer. The method is illustrated with the experimental results of AFM investigations of the special MIM structures with comb-type topology, and of the cells of functioning memory matrices with 20 nm thin silicon dioxide film open edge perimeter and TiN lower electrode, including topography/current profilograms. As a conclusion, our ongoing work on the AFM visualization of a complete perimeter of a SiO2 open edge of memory cells with a special new topology with a goal to visualize conductive phase nanoparticles during switching processes is briefly overviewed.展开更多
Metal-insulator-metal(MIM)cavity as a lithography-free structure to control light transmission and reflection has great potential in the field of optical sensing.However,the dense top metal layer of the MIM prohibits ...Metal-insulator-metal(MIM)cavity as a lithography-free structure to control light transmission and reflection has great potential in the field of optical sensing.However,the dense top metal layer of the MIM prohibits any external medium from entering the dielectric insulation layer,which limits the application of the cavity in the sensing field.Herein,we demonstrate a series of monolithic metal-organic frameworks(MOFs)based MIM cavities,which are treated by plasma etching to provide channels for chemical diffusion and to advance sensing.We modulate the bandwidth of the MIM filters by controlling the MOF thickness as insulator layers.Oxygen plasma-etching is applied to build channels on the top metal layer without altering their saturation and brightness for chemical sensing performance.The etching time regulates the number and size of channels on the top metal layer.Sensing behavior is demonstrated on the plasma-etched MOFs-based MIM cavity when external chemicals diffuse in the cavity.In addition,we generate patterned structure of the MOFs-based MIM cavity via plasma-mask method,which can transfer to different substrates and produce a controllable structure color change for chemical sensing.Our MIM cavity may promote the advancement and applications of structural color in security imaging,color display,information anticounterfeiting,and color printing.展开更多
We propose a highly refractive index sensor based on plasmonic Bow Tie configuration.The sensitivity of the resonator design is enhanced by incorporating a nanowall(NW)in a modified Bow Tie design where sharp tips of ...We propose a highly refractive index sensor based on plasmonic Bow Tie configuration.The sensitivity of the resonator design is enhanced by incorporating a nanowall(NW)in a modified Bow Tie design where sharp tips of V-junction are flattened.This approach provides high confinement of electric field distribution of surface plasmon polariton(SPP)mode in the narrow region of the cavity.Consequently,the effective refractive index(neff)of the mode increases and is highly responsive to the ambient medium.The sensitivity analysis of the SPP mode is calculated for six resonator schemes.The results suggest that the NW embedded cavity offers the highest mode sensitivity due to the large shift of effective index when exposed to a slight change in the medium refractive index.Moreover,the device sensitivity of the proposed design is approximated at 2300 nm/RIU which is much higher than the sensitivity of the standard Bow Tie configuration.展开更多
Nanogap plasmonic structures with strong coupling between separated components have different responses to orthogonal-polarized light, giving rise to giant optical chirality. Here, we proposed a three-dimensional(3D) ...Nanogap plasmonic structures with strong coupling between separated components have different responses to orthogonal-polarized light, giving rise to giant optical chirality. Here, we proposed a three-dimensional(3D) nanostructure that consists of two vertically and twistedly aligned nanogaps, showing the hybridized charge distribution within 3D structures.It is discovered that the structure twisted by 60° exhibits plasmonic coupling behavior with/without gap modes for different circular-polarized plane waves, showing giant chiral response of 60% at the wavelength of 1550 nm. By controlling the disk radius and the insulator layer, the circular dichroism signal can be further tuned between 1538 and 1626 nm.展开更多
In this paper,we describe a new method to improve fast-light transmission,which uses cascades.We design a simple plasmonic device that enables plasmonic-induced absorption(PIA).It consists mainly of two parallel recta...In this paper,we describe a new method to improve fast-light transmission,which uses cascades.We design a simple plasmonic device that enables plasmonic-induced absorption(PIA).It consists mainly of two parallel rectangular cavities.The numerical results simulated by using the finite element method(FEM)confirm its function.The corresponding group delay-time can reach-0.146 ps for the PIA window.Based on this result,we propose a cascade device,with the dual-rectangular cavity system as building block,to improve fast-light transmission even more.The results indicate that the cascade scheme can increase the group delay-time to-0.456 ps,which means the fast-light feature is substantially enhanced compared with the non-cascading approach.The effect of the distance between two cascade resonators and other structural parameters is also investigated.Finally,we use this design concept to build a refractive-index sensor with a sensitivity of 701 nm/RIU.展开更多
基金financial support from A*STAR,SERC 2014 Public Sector Research Funding (PSF) Grant (SERC Project No. 1421200080)
文摘Surface enhanced Raman scattering(SERS)is an efficient technique to detect low concentration molecules.In this work,periodical silicon nanowires(Si NWs)integrated with metal-insulator-metal(MIM)layers are employed as SERS substrates.Laser interference lithography(LIL)combined with reactive ion etching(RIE)is used to fabricate large-area periodic nanostructures,followed by decorating the MIM layers.Compared to MIM disks array on Si surface,the SERS enhancement factor(EF)of the MIM structures on the Si NWs array can be increased up to 5 times,which is attributed to the enhanced electric field at the boundary of the MIM disks.Furthermore,high density of nanoparticles and nanogaps serving as hot spots on sidewall surfaces also contribute to the enhanced SERS signals.Via changing the thickness of the insulator layer,the plasmonic resonance can be tuned,which provides a new localized surface plasmon resonance(LSPR)characteristic for SERS applications.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61605177,61275166,and 11504139)the National Science Fund for Distinguished Young Scholars,China(Grant No.61525107)+4 种基金the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20140167)the Natural Science Foundation of Shanxi Province,China(Grant No.201601D011008)the Fund Program for the Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province,Chinathe Program for the Top Young and Middle-aged Innovative Talents of Higher Learning Institutions of Shanxi Province,Chinathe North University of China Science Fund for Distinguished Young Scholars
文摘A plasmonic waveguide coupled system that is composed of a square ring cavity and a metal-insulator-metal （MIM） waveguide with two silver baffles is proposed. The transmission and reflection properties of the proposed plasmonic system are investigated numerically using the finite element method. The normalized Hz field distributions are calculated to analyze the transmission mode in the plasmonic system. The extreme destructive interference between light mode and dark mode causes plasmonically induced reflection （PIR） window in the transmission spectrum. The PIR window is fitted using the coupled mode theory. The analytical result agrees with the simulation result approximately. In addition, the PIR window can be controlled by adjusting structural parameters and filling different dielectric into the MIM waveguide and the square ring cavity. The results provide a new approach to designing plasmonic devices.
基金Project supported by the Postgraduate Innovation Foundation of Jiangsu Province,China (Grant No.CX09B 090Z)the Key Postgraduate Plan of Nanjing University of Science and Technology,China
文摘To increase the absorption in a thin layer of absorbing material （amorphous silicon, a-Si）, a light trapping design is presented. The designed structure incorporates periodic metal-insulator-metal waveguides to enhance the optical path length of light within the solar cells. The new design can result in broadband optical absorption enhancement not only for transverse magnetic （TM）-polarized light, but also for transverse electric （TE）-polarized light. No plasmonic modes can be excited in TE-polarization, but because of the coupling into the a-Si planar waveguide guiding modes and the diffraction of light by the bottom periodic structures into higher diffraction orders, the total absorption in the active region is also increased. The results from rigorous coupled wave analysis show that the overall optical absorption in the active layer can be greatly enhanced by up to 40%. The designed structures presented in this paper can be integrated with back contact technology to potentially produce high-efficiency thin-film solar cell devices.
基金supported in part by the National Natural Science Foundation of China (Grant Nos. 61875250 and 61975189)the Zhejiang Provincial Natural Science Foundation of China (Grant Nos. LD21F050001 and Y21F040001)+3 种基金the Key Research Project by Department of Water Resources of Zhejiang Province (Grant No. RA2101)the Key Research and Development Project of Zhejiang Province (Grant No. 2021C03019)the Key R&D Projects of Shanxi Province (Grant Nos. 201903D421032 and 01804D131038)the Scientific Research Foundation of Zhejiang University of Water Resources and Electric Power (Grant No. xky2022032)。
文摘A metal-insulator-metal(MIM)-based arc-shaped resonator coupled with a rectangular stub(MARS) structure is proposed. This structure can generate two tunable Fano resonances originating from two different mechanisms. The structure has the advantage of being sensitive to the refractive index, and this feature makes it favorable for application in various microsensors. The relationship between the structural parameters and Fano resonance is researched using the finite element method(FEM) based on the software COMSOL Multiphysics 5.4. The simulation reveals that the sensitivity reaches1900 nm/refractive index unit(RIU), and the figure of merit(FOM) is 23.75.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51405240 and 61178044)the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20161559)+1 种基金the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province of China(Grant No.16KJB510018)University Postgraduate Research and Innovation Project of Jiangsu Province,China(Grant No.KYLX16 1289)
文摘A plasmonic Mach-Zehnder interferometric sensor based on a semicircular aperture-slit nanostructure patterned on a metal-insulator-metal film is proposed and demonstrated by finite difference time domain（FDTD） simulation. Due to the interference between two different surface plasmon polariton modes in this design, the transmission spectra exhibit oscillation behaviors in a broad bandwidth, and can be readily tailored by changing the SPP path length and core layer thickness. Based on this principle, the characteristics of refractive index sensing are also demonstrated by simulation. This structure is illuminated with a collimated light source from the back side to avoid impacts on the interference. Meanwhile,these results show that the proposed structure is promising for portable, efficient, and sensitive biosensing applications.
基金supported by the National Natural Science Foundation of China(Grant No.51965007)the“One thousand Young and Middle-Aged College and University Backbone Teachers Cultivation Program”of Guangxi,China(Grant No.2019)。
文摘Developing a convenient method that can be routinely applied for ascertaining proportions of different vegetable oils employed in commercial blended edible oils remains a significant challenge.We address this issue by proposing a novel method for detecting volume fraction of different oils based on the fact that these oils are optically transparent and have slightly different indices of refraction at a given temperature and wavelength.Accordingly,we develop a highly sensitive sensor for measuring the index of refraction of oil blends based on Fano resonance spectra obtained using a metal-insulatormetal(MIM)waveguide structure comprising a gapped straight waveguide coupled with two L-shaped resonators.The index of refraction sensitivity and figure of merit of the structure are calculated based on modeling using the finite element method,and the waveguide structure is accordingly optimized by adjusting the different geometric parameters to achieve a high-quality Fano resonance spectrum.The optimized structure achieves an ultra-high refractive index sensitivity of 770 nm/RIU in terms of a refractive index unit(RIU)of 1.Moreover,a highly stable linear relationship is obtained between the refractive index of mixed edible oils and the resonance wavelength.Experimental results demonstrate that the proposed structure can detect slight changes in the volume fractions of the components in blended oils.
基金supported by the National Natural Science Foundation of China(Nos.62075132 and 92050202)Natural Science Foundation of Shanghai(No.22ZR1443100).
文摘The chiral feature of an optical field can be evaluated by the parameter of g-factor enhancement,which is helpful to enhance chiroptic signals from a chiral dipole.In this work,the superchiral spot has been theoretically proposed in metal-insulator-metal waveguides.The g-factor enhancement of the superchiral spot can be enhanced by 67-fold more than that of circularly polarized light,and the spot is confined in the deep wavelength scale along each spatial dimension.Moreover,the position of the superchiral spot can be tuned by manipulating the incident field.The tunable superchiral spot may find applications in chiral imaging and sensing.
文摘A fabrication process based on the self-assembling polystyrene spheres is proposed to obtain hole arrayed metal-insulator-metal （HA-MIM） structure for surface enhanced Raman scattering （SERS）. The localized field enhancement aroused by the gap resonance in the HA-MIM structure is analyzed by finite-different time domain （FDTD） method. With reference to the theory result, the structure is experimentally fabricated and the Raman scattering spectrum of rhodamine 6G （R6G） is measured by a miniaturized Raman spectrometer. The results shows that the enhancement factor is 3.85 times higher than the control sample with single layered metal hole array. The fabrication process to obtain the HA-MIM SERS substrate is reproducible, fast, large area and low cost.
基金National Natural Science Foundation of China(NSFC)(61571399)“The Belt and Road”International Cooperation of Zhejiang Province,China(2015C04005)
文摘We propose a design for efficient end-fire coupling of surface plasmon polaritons in a metal-insulator-metal(MIM) waveguide with an optical fiber as part of a simple photoplastic connector. The design was analyzed and optimized using the three-dimensional finite-difference time-domain method. The calculated excitation efficiency coefficient of the waveguide is 83.7%(-0.77 dB) at a wavelength of 405 nm. This design enables simple connection of an optical fiber to a MIM waveguide and highly efficient local excitation of the waveguide.Moreover, the length of the metallic elements of the waveguide, and thus the dissipative losses, can be reduced.The proposed design may be useful in plasmonic-type waveguide applications such as near-field investigation of live cells and other objects with super-resolution.
基金supported by the National Key Research and Development Program of China(Grant No.2019YFB1803505)the National Natural Science Foundation of China(Grant Nos.U2001601,62175039,and 61925501)+3 种基金the Science and Technology Project of Guangzhou(Grant No.201904010243)Major Special Projects in Guangdong Province(Grant No.2018B010114002)the Engineering Research Center of Digital Imaging and Display,Ministry of Education,Soochow University(Grant No.SDGC2133)the Program for Guangdong Introducing Innovative and Enterpreneurial Teams.
文摘In this paper,a Bragg reflector is proposed by placing periodic metallic gratings in the center of a metal-insulator-metal(MIM)waveguide.According to the effective refractive index modulation caused by different waveguide widths in a period,a reflection channel with a large bandwidth is firstly achieved.Besides,the Mach-Zehnder interference(MZI)effect arises by shifting the gratings away from the waveguide center.Owing to different optical paths with unequal indices on both sides of the grating,a narrow MZI band gap will be obtained.It is interesting to find out that the Bragg reflector and Mach-Zehnder interferometer are immune to each other,and their wavelengths can be manipulated by the period and the grating length,respectively.Additionally,we can obtain three MZI channels and one Bragg reflection channel by integrating three different gratings into a large period.The performances are investigated by finite-difference time-domain(FDTD)simulations.In the index range of 1.33–1.36,the maximum sensitivity for the structure is as high as 1500 nm/RIU,and it is believed that this proposed structure can find widely applications in the chip-scale optical communication and sensing areas.
基金Project supported by the National Natural Science Foundation of China （Grant No 90607023）, Shanghai Pujiang Program （Grant No 05PJ14017）, SRF for R0CS, SEM, and the Micro/Nano-electronics Science and Technology Innovation Platform （985） and the Ministry of Education of China in the International Research Training Group ＂Materials and Concepts for Advanced Interconnects
文摘Metal-insulator-metal （MIM） capacitors with atomic-layer-deposited Al2O3 dielectric and reactively sputtered TaN electrodes in application to radio frequency integrated circuits have been characterized electrically. The capacitors exhibit a high density of about 6.05 fF/μm^2, a small leakage current of 4.8 × 10^-8 A/cm^2 at 3 V, a high breakdown electric field of 8.61 MV/cm as well as acceptable voltage coefficients of capacitance （VCCs） of 795 ppm/V2 and 268ppm/V at 1 MHz. The observed properties should be attributed to high-quality Al2O3 film and chemically stable TaN electrodes. Further, a logarithmically linear relationship between quadratic VCC and frequency is observed due to the change of relaxation time with carrier mobility in the dielectric. The conduction mechanism in the high field ranges is dominated by the Poole-Frenkel emission, and the leakage current in the low field ranges is likely to be associated with trap-assisted tunnelling. Meanwhile, the Al2O3 dielectric presents charge trapping under low voltage stresses, and defect generation under high voltage stresses, and it has a hard-breakdown performance.
基金Project(61275174)supported by the National Natural Science Foundations of ChinaProject(20100162110068)supported by the Doctoral Program of Higher Education of China
文摘Based on Fabry model and finite-different time-domain(FDTD) method, the plasmonic structure composed of a metal-insulator-metal(MIM) bus waveguide and a side-coupled resonator was investigated. It is found that the transmission features can be regulated by the cavity width and coupling distance. Electromagnetically induced transparency(EIT)-like transmission can be excited by adding an identical resonator on the pre-existing structure. Combining the foregoing theoretical analysis with coupled mode theory(CMT), the formation process of the EIT-like transmission was detailedly analyzed. EIT-like transmission can also be excited in plasmonic structure with two detuned resonators. By altering the structure parameters, the transparency window can be purposefully modulated. With the merits of compact structure and simplicity in fabrication, the proposed structures may have a broad prospect of applications in highly integrated optical circuits.
文摘We propose and analyze a submicron stub-assisted ultrafast all-optical plasmonic switch based on nonlinear MIM waveguide. It is constructed by two silicon stub filters sandwiched by silver cladding. The signal wavelength is assumed to be 1550 nm. The simulation results show a ?14.66 dB extinction ratio. Downscaling the silicon waveguide in MIM structure leads to enhancement of the effective Kerr nonlinearity due to tight mode confinement. Also, using O+ ions implanted into silicon, the switching time less than 10 ps and a delay time less than 8 fs are achieved. The overall length of the switch is 550 nm.
文摘A novel hybrid structure with high responsivity and efficiency is proposed based on an L-shaped frame nano-antenna(LSFNA)array for solar energy harvesting application.So,two types of LSFNAs are designed and optimized to enhance the harvesting characteristics of traditional simple electric dipole nano-antenna(SEDNA).The LSFNA geometrical dimensions are optimized to have the best values for the required input impedance at three resonance wavelengths ofλ_(res)=10μm,15μm,and 20μm.Then the LSFNAs with three different sizes are modeled like a planar spiral-shaped array(PSSA).Also,a fractal bowtie nano-antenna is connected with the PSSA in the array gap.This proposed hybrid structure consists of two main elements:(I)Three different sizes of the LSFNAs with two different material types are designed based on the thin-film metal-insulator-metal diodes that are a proper method for infrared energy harvesting.(Ⅱ)The PSSA gap is designed based on the electron field emission proposed by the Fowler-Nordheim theory for the array rectification.Finally,the proposed device is analyzed.The results show that the PSSA not only has an averaged 3-time enhancement in the harvesting characteristics(such as return loss,harvesting efficiency,etc.)than the previously proposed structures but also is a multi-resonance wide-band device.Furthermore,the proposed antenna takes up less space in the electronic circuit and has an easy implementation process.
文摘In this work, a development of a method of a thin insulating film vertical edge visualization of metal-insulator-metal （MIM） memory cells with atomic force microscopy （AFM） using a modified Omicron UHV AFM/STM microscope was performed. This included a development of a technique of the AFM visualization of segments of a vertical edge of thin insulator SiO2 film structures on a conductive substrate, a comparison of AFM topography and current profilograms for the edge profiles, and an Omicron microscope custom upgrade. The latter allowed us to perform the AFM probe positioning to any specific area of the sample in the scanning plane by two coordinates with an order of precision of 1 micrometer. The method is illustrated with the experimental results of AFM investigations of the special MIM structures with comb-type topology, and of the cells of functioning memory matrices with 20 nm thin silicon dioxide film open edge perimeter and TiN lower electrode, including topography/current profilograms. As a conclusion, our ongoing work on the AFM visualization of a complete perimeter of a SiO2 open edge of memory cells with a special new topology with a goal to visualize conductive phase nanoparticles during switching processes is briefly overviewed.
基金support from the National Natural Science Foundations of China(No.52071270)the Science Fund of Shandong Laboratory of Advanced Materials and Green Manufacturing(Yantai)(No.AMGM2023F03)+1 种基金Guangdong Basic and Applied Basic Research Foundation(No.2021A1515410006)the Research Fund of the State Key Laboratory of Solidification Processing(NPU)(No.2022-QZ-04).
文摘Metal-insulator-metal(MIM)cavity as a lithography-free structure to control light transmission and reflection has great potential in the field of optical sensing.However,the dense top metal layer of the MIM prohibits any external medium from entering the dielectric insulation layer,which limits the application of the cavity in the sensing field.Herein,we demonstrate a series of monolithic metal-organic frameworks(MOFs)based MIM cavities,which are treated by plasma etching to provide channels for chemical diffusion and to advance sensing.We modulate the bandwidth of the MIM filters by controlling the MOF thickness as insulator layers.Oxygen plasma-etching is applied to build channels on the top metal layer without altering their saturation and brightness for chemical sensing performance.The etching time regulates the number and size of channels on the top metal layer.Sensing behavior is demonstrated on the plasma-etched MOFs-based MIM cavity when external chemicals diffuse in the cavity.In addition,we generate patterned structure of the MOFs-based MIM cavity via plasma-mask method,which can transfer to different substrates and produce a controllable structure color change for chemical sensing.Our MIM cavity may promote the advancement and applications of structural color in security imaging,color display,information anticounterfeiting,and color printing.
基金This work was financially supported by the Ministry of Science and Higher Education within the State assignment FSRC“Crystallography and Photonics”RAS(Grant No.007-GZ/Ch3363/26).
文摘We propose a highly refractive index sensor based on plasmonic Bow Tie configuration.The sensitivity of the resonator design is enhanced by incorporating a nanowall(NW)in a modified Bow Tie design where sharp tips of V-junction are flattened.This approach provides high confinement of electric field distribution of surface plasmon polariton(SPP)mode in the narrow region of the cavity.Consequently,the effective refractive index(neff)of the mode increases and is highly responsive to the ambient medium.The sensitivity analysis of the SPP mode is calculated for six resonator schemes.The results suggest that the NW embedded cavity offers the highest mode sensitivity due to the large shift of effective index when exposed to a slight change in the medium refractive index.Moreover,the device sensitivity of the proposed design is approximated at 2300 nm/RIU which is much higher than the sensitivity of the standard Bow Tie configuration.
基金the National Natural Science Foundation of China (Nos. U1704253 and 51471045)the Zhejiang Provincial Foundation for Distinguished Young Scholars (No. LR18E010001)+1 种基金the Zhejiang Provincial Key Research and Development Program (No. 2019C01121)the start-up funding supported from the Hangzhou Dianzi University。
文摘Nanogap plasmonic structures with strong coupling between separated components have different responses to orthogonal-polarized light, giving rise to giant optical chirality. Here, we proposed a three-dimensional(3D) nanostructure that consists of two vertically and twistedly aligned nanogaps, showing the hybridized charge distribution within 3D structures.It is discovered that the structure twisted by 60° exhibits plasmonic coupling behavior with/without gap modes for different circular-polarized plane waves, showing giant chiral response of 60% at the wavelength of 1550 nm. By controlling the disk radius and the insulator layer, the circular dichroism signal can be further tuned between 1538 and 1626 nm.
基金supported by the National Natural Science Foundation of China(Grant No.61367007)the Natural Science Fund of Gansu Province of China(Grant Nos.17JR5RA123 and 17JR5RA132)the HongLiu First-Class disciplines Development Program of Lanzhou University of Technology.
文摘In this paper,we describe a new method to improve fast-light transmission,which uses cascades.We design a simple plasmonic device that enables plasmonic-induced absorption(PIA).It consists mainly of two parallel rectangular cavities.The numerical results simulated by using the finite element method(FEM)confirm its function.The corresponding group delay-time can reach-0.146 ps for the PIA window.Based on this result,we propose a cascade device,with the dual-rectangular cavity system as building block,to improve fast-light transmission even more.The results indicate that the cascade scheme can increase the group delay-time to-0.456 ps,which means the fast-light feature is substantially enhanced compared with the non-cascading approach.The effect of the distance between two cascade resonators and other structural parameters is also investigated.Finally,we use this design concept to build a refractive-index sensor with a sensitivity of 701 nm/RIU.
