A novel nanolaser structure based on a hybrid plasmonic waveguide is proposed and investigated. The coupling between the metal nanowire and the high-index semiconductor nanowire with optical gain leads to a strong fie...A novel nanolaser structure based on a hybrid plasmonic waveguide is proposed and investigated. The coupling between the metal nanowire and the high-index semiconductor nanowire with optical gain leads to a strong field enhancement in the air gap region and low propagation loss, which enables the realization of lasing at the deep subwavelength scale.By optimizing the geometric parameters of the structure, a minimal lasing threshold is achieved while maintaining the capacity of ultra-deep subwavelength mode confinement. Compared with the previous coupled nanowire pair based hybrid plasmonic structure, a lower threshold can be obtained with the same geometric parameters. The proposed nanolaser can be integrated into a miniature chip as a nanoscale light source and has the potential to be widely used in optical communication and optical sensing technology.展开更多
A high-sensitivity plasmonic refractive-index sensor based on the asymmetrical coupling of two metal-insulator- metal waveguides with a nanodisk resonator is proposed and simulated in the finite-difference time domain...A high-sensitivity plasmonic refractive-index sensor based on the asymmetrical coupling of two metal-insulator- metal waveguides with a nanodisk resonator is proposed and simulated in the finite-difference time domain. Both analytic and simulated results show that the resonance wavelengths of the sensor have an approximate linear relationship with the refractive index of the materials which are filled into the slit waveguides and the disk- shaped resonator. The working mechanism of this sensor is exactly due to the linear relationship, based on which tile refractive index of the materials unknown can be obtained from the detection of the resonance wavelength. The measurement sensitivity can reach as high as 6.45 × 10-7, which is nearly five times higher than the results reported in the recent literature [Opt. Commun. 300 （2013） 265]. With an optimum design, the sensing value can be further improved, and it can be widely applied into the biological sensing. Tile sensor working for temperature sensing is also analyzed.展开更多
We study the dynamics of the quantum steering between two separated qubits trapped in a one-dimensional plasmonic waveguide.By numerical methods,we calculate the quantum steerability and other quantum correlations,i.e...We study the dynamics of the quantum steering between two separated qubits trapped in a one-dimensional plasmonic waveguide.By numerical methods,we calculate the quantum steerability and other quantum correlations,i.e.,entanglement,discord,and coherence,for both cases with and without laser driving fields.It is found that steerability may exhibit a sudden disappearance and sudden reappearance phenomenon.Specifically,there exist time windows with no steerability but finite entanglement.The effects of plasmon wavenumber and the distance between the two qubits on steerability are also examined.Furthermore,we show that quantum steerability is tunable by adjusting the laser driving fields.展开更多
We explore the dispersion properties and optical gradient forces from mutual coupling of surface plasmon polariton（SPP） modes at two interfaces of nanoscale plasmonic waveguides with hyperbolic metamaterial cladding...We explore the dispersion properties and optical gradient forces from mutual coupling of surface plasmon polariton（SPP） modes at two interfaces of nanoscale plasmonic waveguides with hyperbolic metamaterial cladding.With Maxwell＇s equations and Maxwell stress tensor,we calculate and compare the dispersion relation and optical gradient force for symmetric and antisymmetric SPP modes in two kinds of nanoscale plasmonic waveguides.The numerical results show that the optical gradient force between two coupled hyperbolic metamaterial waveguides can be engineered flexibly by adjusting the waveguide structure parameters.Importantly,an alternative way to boost the optical gradient force is provided through engineering the hyperbolic metamaterial cladding of suitable orientation.These special optical properties will open the door for potential optomechanical applications,such as optical tweezers and actuators.展开更多
Polarizing beam splitter has rather significant applications in polarization diversity circuits and polarization multiplexing systems.In this paper,we present an asymmetric polarizing beam splitter utilizing hybrid pl...Polarizing beam splitter has rather significant applications in polarization diversity circuits and polarization multiplexing systems.In this paper,we present an asymmetric polarizing beam splitter utilizing hybrid plasmonic waveguide.The special hybrid structure with a hybrid waveguide and a dielectric waveguide can limit the energy of TE and TM modes to a different layer.Therefore,we can achieve beam splitting by adjusting the corresponding parameters of the two waveguides.First,we studied the influences of different structure parameters on the real part of the effective mode refractive index of the two waveguides,and obtained a set of parameters that satisfy the condition of strong coupling of TM mode and weak coupling of TE mode.Then,the performance of our proposed polarizing beam splitter is evaluated numerically.The length of the coupling section is only 4.1μm,and the propagation loss of TM and TE modes is 0.0025 d B/μm and 0.0031 d B/μm respectively.Additionally,the extinction ratios of TM and TE modes are 10.62 d B and 12.55 d B,respectively.Particularly,the proposed device has excellent wavelength insensitivity.Over the entire C-band,the fluctuation of the whole normalized output power is less than 0.03.In short,our proposed asymmetric polarizing beam splitter features ultra-compactness,low propagation loss,and broad bandwidth,which would provide promising applications in polarization multiplexing system and polarization diversity circuits relevant to optical interconnection.展开更多
Hybrid plasmon waveguides, respectively, with metamaterial substrate and dielectric substrate are investigated and analyzed contrastively with a numerical finite element method. Basic properties, including propagation...Hybrid plasmon waveguides, respectively, with metamaterial substrate and dielectric substrate are investigated and analyzed contrastively with a numerical finite element method. Basic properties, including propagation length Lp, effective mode area Aeff, and energy distribution, are obtained and compared with waveguide geometric parameters at 1.55 gin. For the waveguide with metamaterial substrate, propagation length Lp increases to several tens of microns and effective mode area Aeff is reduced by more than 3 times. Moreover, the near field region is expanded, leading to potential applications in nanophotonics. Therefore, it could be very helpful for improving the integration density in optical chips and developing functional components on a nanometer scale for all optical integrated circuits.展开更多
An ultra-wideband bandpass filter(BPF)with a wide out-of-band rejection based on a surface plasmonic waveguide(SPW)slotline with ring grooves is designed and analyzed.A paired microstrip-to-slotline transition is desi...An ultra-wideband bandpass filter(BPF)with a wide out-of-band rejection based on a surface plasmonic waveguide(SPW)slotline with ring grooves is designed and analyzed.A paired microstrip-to-slotline transition is designed for quasiTEM to TM mode conversion by using a microstrip line with a circular pad and the slotline with the same circular slot.The mode conversion between the TM and the surface plasmon polariton(SPP)mode is realized by using a gradient slotline with ring grooves and an impedance matching technique.The upper cut-off frequencies of the passband can be adjusted by using these proposed SPP units,while the lower frequencies of the passband are created by using the microstrip-toslotline transitions to give an ultra-wideband BPF.The dispersion curves of SPP units,electric field distribution,and the transmission spectra of the proposed ultra-wideband bandpass filter are all calculated and analyzed by the finite-difference time-domain(FDTD)method.The simulated results show that the presented filter has good performance including a wide3-dB bandwidth of 149%from 0.57 GHz to 3.93 GHz,an extremely wide 40-dB upper-band rejection from 4.2 GHz to18.5 GHz,and low loss and high selectivity in the passband.To prove the design validity,a prototype of the BPF has been manufactured and measured,showing a reasonable agreement with simulation results.The unique features of the proposed BPF may make it applicable for integrated circuit and plasmonic devices in microwave or THz frequency ranges.展开更多
The propagation length of surface plasmon polaritons（SPPs） is intrinsically limited by the metallic ohmic loss that is enhanced by the strongly confined electromagnetic field. In this paper, we propose a new class o...The propagation length of surface plasmon polaritons（SPPs） is intrinsically limited by the metallic ohmic loss that is enhanced by the strongly confined electromagnetic field. In this paper, we propose a new class of hybrid plasmonic waveguides（HPWs） that can support long-range SPP propagation while keeping subwavelength optical field confinement. It is shown that the coupling between the waveguides can be well tuned by simply varying the structural parameters. Compared with conventional HPWs, a larger propagation length as well as a better optical field confinement can be simultaneously realized. The proposed structure with better optical performance can be useful for future photonic device design and optical integration research.展开更多
According to the electromagnetic field distributions, there exist two kinds of coupled spoof surface plasmon polaritons（SSPPs）, the symmetric and anti-symmetric modes, in the three-dimensional（3D） subwavelength sp...According to the electromagnetic field distributions, there exist two kinds of coupled spoof surface plasmon polaritons（SSPPs）, the symmetric and anti-symmetric modes, in the three-dimensional（3D） subwavelength spoof–insulator–spoof（SIS） waveguide. We study the dispersion and excitation of the two kinds of coupled SSPPs supported by the 3D SIS waveguide. The evolution of the dispersion with the thickness and gap width of the waveguide is numerically investigated,and we give a theoretical analysis according to the coupling mechanism. Specially, based on the coupling mechanism,we design a zipper structure, through which the excitation and propagation of the anti-symmetric coupled modes can be realized effectively.展开更多
A surface plasmon resonance(SPR)sensor with Ag/PbS/GR hybrid nanostructure has been proposed for the diagnostics of liquid phase samples.Here Ag/PbS/GR hybrid nanostructure is designed as an asymmetric MIM waveguide f...A surface plasmon resonance(SPR)sensor with Ag/PbS/GR hybrid nanostructure has been proposed for the diagnostics of liquid phase samples.Here Ag/PbS/GR hybrid nanostructure is designed as an asymmetric MIM waveguide for surface plasmon.Due to the guided wave SPR(GWSPR)modes,the index of the liquid phase samples can be measured more accurately than the conventional SPR sensors.Numerical simulation results show that the sensitivity of the sensor is about 5 times higher than the conventional SPR sensors.The origin of the enhancement mechanism is the combination of GWSPR in the Ag/PbS/GR hybrid nanostructure which enables the surface plasmon to spread along the PbS layer.In Ag/PbS/GR hybrid nanostructure,the electric field is concentrated mostly in the PbS layer,and the enhancement of the field intensity is nearly30%.展开更多
Surface plasmon polariton（SPP）, a sub-wavelength surface wave promising for photonic integration, always suffers from the large metallic loss that seriously restricts its practical application. Here, we propose a co...Surface plasmon polariton（SPP）, a sub-wavelength surface wave promising for photonic integration, always suffers from the large metallic loss that seriously restricts its practical application. Here, we propose a compact SPP amplifier based on a nonlinear hybrid waveguide（a combination of silver, LiNbO3, and SiO2）, where a couple of Bragg gratings are introduced in the waveguide to construct a cavity. This special waveguide is demonstrated to support a highly localized SPP-like hybrid mode and a low loss waveguide-like hybrid mode. To provide a large nonlinear gain, a pumping wave input from the LiNbO3 waveguide is designed to resonate inside the cavity and satisfy the cavity phase matching to fulfill the optical parametric amplification（OPA） of the SPP signal. Proper periods of gratings and the cavity length are chosen to satisfy the impedance matching condition to ensure the high input efficiency of the pump wave from the outside into the cavity. In theoretical calculations, this device demonstrates a high performance in a very compact scheme（~3.32 μm） and a much lower pumping power for OPA compared with single-pass pumping. To obtain a comprehensive insight into this cavity OPA, the influences of the pumping power, cavity length, and the initial phase are discussed in detail.展开更多
An ultrafast and low-power slow light tuning mechanism based on plasmon-induced transparency(PIT)for two disk cavities aperture-coupled to a metal-dielectric-metal plasmonic waveguide system is investigated numericall...An ultrafast and low-power slow light tuning mechanism based on plasmon-induced transparency(PIT)for two disk cavities aperture-coupled to a metal-dielectric-metal plasmonic waveguide system is investigated numerically and analytically.The optical Kerr effect is enhanced by the local electromagnetic field of surface plasmon polaritons,slow light,and graphene-Ag composite material structures with a large effective Kerr nonlinear coefficient.Through the dynamic adjustment of the frequency of the disk nanocavity,the group velocity is controlled between c/53.2 and c/15.1 with the pump light intensity increased from 0.41 MW/cm^2 to 2.05 MW/cm^2.Alternatively,through the dynamic adjustment of the propagation phase of the plasmonic waveguide,the group velocity is controlled between c/2.8 and c/14.8 with the pump light intensity increased from 5.88 MW/cm^2 to 11.76 MW/cm^2.The phase shift multiplication of the PIT effect is observed.Calculation results indicate that the entire structure is ultracompact and has a footprint of less than 0.8μm^2.An ultrafast responsive time in the order of 1 ps is reached due to the ultrafast carrier relaxation dynamics of graphene.All findings are comprehensively analyzed through finite-difference time-domain simulations and with a coupling-mode equation system.The results can serve as a reference for the design and fabrication of nanoscale integration photonic devices with low power consumption and ultrafast nonlinear responses.展开更多
In photonie integrated circuits, information is usually encoded in the optical path. In this work, based on the multi-mode dielectric-loaded surface plasmon polariton waveguide, we numerically design a directional cou...In photonie integrated circuits, information is usually encoded in the optical path. In this work, based on the multi-mode dielectric-loaded surface plasmon polariton waveguide, we numerically design a directional coupler, which can divide the different waveguide eigenmodes into different optical paths. The results show a possibility to encode information onto different waveguide modes. We also experimentally demonstrate that the splitting ratio of this directional coupler structure can be tuned without changing its size.展开更多
The large negative permittivity of noble metals in the infrared region prevents the possibility of highly confined plasmons in simple waveguide structures such as thin films or rods. This is a critical obstacle to app...The large negative permittivity of noble metals in the infrared region prevents the possibility of highly confined plasmons in simple waveguide structures such as thin films or rods. This is a critical obstacle to applications of nonlinear plasmonics in the telecommunication wavelength region. We theoretically propose and numerically demonstrate that such limitation can be overcome by exploiting inter-element coupling effects in a plasmonic waveguide array. The supermodes of a plasmonic array span a large range of effective indices, making these structures ideal for broadband mode-multiplexed interconnects for integrated photonic devices. We show such plasmonic waveguide arrays can significantly enhance nonlinear optical interactions when operating in a high-index, tightly bound supermode. For example, a third-order nonlinear coeffident in such a waveguide can be more than three orders of magnitude larger compared to silicon waveguides of similar dimensions. These findings open new design possibilities towards the application of plasmonics in integrated optical devices in the telecommunications spectral region.展开更多
Due to its amazing ability to manipulate light at the nanoscale,plasmonics has become one of the most interesting topics in the field of light–matter interaction.As a promising application of plasmonics,surface-enhan...Due to its amazing ability to manipulate light at the nanoscale,plasmonics has become one of the most interesting topics in the field of light–matter interaction.As a promising application of plasmonics,surface-enhanced Raman scattering(SERS)has been widely used in scientific investigations and material analysis.The large enhanced Raman signals are mainly caused by the extremely enhanced electromagnetic field that results from localized surface plasmon polaritons.Recently,a novel SERS technology called remote SERS has been reported,combining both localized surface plasmon polaritons and propagating surface plasmon polaritons(PSPPs,or called plasmonic waveguide),which may be found in prominent applications in special circumstances compared to traditional local SERS.In this article,we review the mechanism of remote SERS and its development since it was first reported in 2009.Various remote metal systems based on plasmonic waveguides,such as nanoparticle–nanowire systems,single nanowire systems,crossed nanowire systems and nanowire dimer systems,are introduced,and recent novel applications,such as sensors,plasmon-driven surface-catalyzed reactions and Raman optical activity,are also presented.Furthermore,studies of remote SERS in dielectric and organic systems based on dielectric waveguides remind us that this useful technology has additional,tremendous application prospects that have not been realized in metal systems.展开更多
We demonstrate the possibility of dual-band unidirectional reflectionlessness in a non-Hermitian quantum system composed of a plasmonic waveguide and two end-coupled plasmonic cavities(PCs).Our scheme exhibits dual-ba...We demonstrate the possibility of dual-band unidirectional reflectionlessness in a non-Hermitian quantum system composed of a plasmonic waveguide and two end-coupled plasmonic cavities(PCs).Our scheme exhibits dual-band unidirectional reflectionlessness can be obtained at exceptional points by properly adjusting the coupling strength between two PCs,the ratio of decay rates of two PCs,and the ratio of plasmonic cavity-waveguide coupling strengths.As a valuable feature,the quality factor reaches to~175.4 in forward direction,while the backward quality factor is close to~188.2.展开更多
We suggest a low cross-talk plasmonic cross-connector based on a metal/insulator/metal cavity and waveguides.We separately investigate the isolated cavity mode, the waveguide mode, and the combination of cavity and wa...We suggest a low cross-talk plasmonic cross-connector based on a metal/insulator/metal cavity and waveguides.We separately investigate the isolated cavity mode, the waveguide mode, and the combination of cavity and waveguide modes using a finite-different time-domain method. Due to resonant tunneling and the cutoff frequency of the odd waveguide mode, our proposed structure achieves a high throughput transmission ratio and eliminates cross-talk. Furthermore, the proposed structure has a broadband tunability of 587 nm, which can be achieved by modulating the cavity air gap thickness. This structure enables the miniaturization of photonic integrated circuits and sensing applications.展开更多
We propose a polarization-insensitive design of a hybrid plasmonic waveguide(HPWG)optimized at the 3.392µm wavelength which corresponds to the absorption line of methane gas.The waveguide design is capable of pro...We propose a polarization-insensitive design of a hybrid plasmonic waveguide(HPWG)optimized at the 3.392µm wavelength which corresponds to the absorption line of methane gas.The waveguide design is capable of providing high mode sensitivity(Smode)and evanescent field ratio(EFR)for both transverse electric(TE)and transverse magnetic(TM)hybrid modes.The modal analysis of the waveguide is performed via 2-dimension(2D)and 3-dimension(3D)finite element methods(FEMs).At optimized waveguide parameters,Smode and EFR of 0.94 and 0.704,can be obtained for the TE hybrid mode,respectively,whereas the TM hybrid mode can offer Smode and EFR of 0.86 and 0.67,respectively.The TE and TM hybrid modes power dissipation of~3 dB can be obtained for a 20-µm-long hybrid plasmonic waveguide at the 60%gas concentration.We believe that the highly sensitive waveguide scheme proposed in this work overcomes the limitation of the polarization controlled light and can be utilized in gas sensing applications.展开更多
A nonlinear hybrid plasmonic slot waveguide composed of periodically poled lithium niobate(PPLN) and two separated silver films is investigated. The e?ective refractive index, propagation length, and energy confinemen...A nonlinear hybrid plasmonic slot waveguide composed of periodically poled lithium niobate(PPLN) and two separated silver films is investigated. The e?ective refractive index, propagation length, and energy confinement of the hybrid anti-symmetric mode in this waveguide are calculated using the structure parameters at the fundamental wavelength of λ = 1550 nm and its second harmonic(SH) λ = 775 nm. Through the above indices, coupling e?ciency(maximum SH conversion e?ciency during propagation) and peak position(propagation location of the conversion e?ciency) of SH generation are analyzed. Finally, higher conversion e?ciency can be achieved at a shorter propagation distance by changing the waveguide into a tapered structure.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.61172044)the Natural Science Foundation of Hebei Province,China(Grant No.F2014501150)
文摘A novel nanolaser structure based on a hybrid plasmonic waveguide is proposed and investigated. The coupling between the metal nanowire and the high-index semiconductor nanowire with optical gain leads to a strong field enhancement in the air gap region and low propagation loss, which enables the realization of lasing at the deep subwavelength scale.By optimizing the geometric parameters of the structure, a minimal lasing threshold is achieved while maintaining the capacity of ultra-deep subwavelength mode confinement. Compared with the previous coupled nanowire pair based hybrid plasmonic structure, a lower threshold can be obtained with the same geometric parameters. The proposed nanolaser can be integrated into a miniature chip as a nanoscale light source and has the potential to be widely used in optical communication and optical sensing technology.
基金Supported by the National Natural Science Foundation of China under Grant No 61275059
文摘A high-sensitivity plasmonic refractive-index sensor based on the asymmetrical coupling of two metal-insulator- metal waveguides with a nanodisk resonator is proposed and simulated in the finite-difference time domain. Both analytic and simulated results show that the resonance wavelengths of the sensor have an approximate linear relationship with the refractive index of the materials which are filled into the slit waveguides and the disk- shaped resonator. The working mechanism of this sensor is exactly due to the linear relationship, based on which tile refractive index of the materials unknown can be obtained from the detection of the resonance wavelength. The measurement sensitivity can reach as high as 6.45 × 10-7, which is nearly five times higher than the results reported in the recent literature [Opt. Commun. 300 （2013） 265]. With an optimum design, the sensing value can be further improved, and it can be widely applied into the biological sensing. Tile sensor working for temperature sensing is also analyzed.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51876059 and 11805065)the Fundamental Research Funds for the Central Universities(Grant Nos.2021MS009 and 2021MS046)
文摘We study the dynamics of the quantum steering between two separated qubits trapped in a one-dimensional plasmonic waveguide.By numerical methods,we calculate the quantum steerability and other quantum correlations,i.e.,entanglement,discord,and coherence,for both cases with and without laser driving fields.It is found that steerability may exhibit a sudden disappearance and sudden reappearance phenomenon.Specifically,there exist time windows with no steerability but finite entanglement.The effects of plasmon wavenumber and the distance between the two qubits on steerability are also examined.Furthermore,we show that quantum steerability is tunable by adjusting the laser driving fields.
基金Project supported by the National Natural Science Foundation of China(Grant No.11474106)the Natural Science Foundation of Guangdong Province,China(Grant No.2016A030313439)
文摘We explore the dispersion properties and optical gradient forces from mutual coupling of surface plasmon polariton（SPP） modes at two interfaces of nanoscale plasmonic waveguides with hyperbolic metamaterial cladding.With Maxwell＇s equations and Maxwell stress tensor,we calculate and compare the dispersion relation and optical gradient force for symmetric and antisymmetric SPP modes in two kinds of nanoscale plasmonic waveguides.The numerical results show that the optical gradient force between two coupled hyperbolic metamaterial waveguides can be engineered flexibly by adjusting the waveguide structure parameters.Importantly,an alternative way to boost the optical gradient force is provided through engineering the hyperbolic metamaterial cladding of suitable orientation.These special optical properties will open the door for potential optomechanical applications,such as optical tweezers and actuators.
基金supported by the Shenzhen Science and Technology Program(JCYJ20210324093806017)the ShenzhenHong Kong Joint Innovation Foundation(SGDX20190919094401725)。
文摘Polarizing beam splitter has rather significant applications in polarization diversity circuits and polarization multiplexing systems.In this paper,we present an asymmetric polarizing beam splitter utilizing hybrid plasmonic waveguide.The special hybrid structure with a hybrid waveguide and a dielectric waveguide can limit the energy of TE and TM modes to a different layer.Therefore,we can achieve beam splitting by adjusting the corresponding parameters of the two waveguides.First,we studied the influences of different structure parameters on the real part of the effective mode refractive index of the two waveguides,and obtained a set of parameters that satisfy the condition of strong coupling of TM mode and weak coupling of TE mode.Then,the performance of our proposed polarizing beam splitter is evaluated numerically.The length of the coupling section is only 4.1μm,and the propagation loss of TM and TE modes is 0.0025 d B/μm and 0.0031 d B/μm respectively.Additionally,the extinction ratios of TM and TE modes are 10.62 d B and 12.55 d B,respectively.Particularly,the proposed device has excellent wavelength insensitivity.Over the entire C-band,the fluctuation of the whole normalized output power is less than 0.03.In short,our proposed asymmetric polarizing beam splitter features ultra-compactness,low propagation loss,and broad bandwidth,which would provide promising applications in polarization multiplexing system and polarization diversity circuits relevant to optical interconnection.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.60908028,60971068,10979065,and 61275201)the Program for the New Century Excellent Talents in University,China(Grant No.NCET-10-0261)
文摘Hybrid plasmon waveguides, respectively, with metamaterial substrate and dielectric substrate are investigated and analyzed contrastively with a numerical finite element method. Basic properties, including propagation length Lp, effective mode area Aeff, and energy distribution, are obtained and compared with waveguide geometric parameters at 1.55 gin. For the waveguide with metamaterial substrate, propagation length Lp increases to several tens of microns and effective mode area Aeff is reduced by more than 3 times. Moreover, the near field region is expanded, leading to potential applications in nanophotonics. Therefore, it could be very helpful for improving the integration density in optical chips and developing functional components on a nanometer scale for all optical integrated circuits.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.U2141232,62071221,and 62071442)the Aeronautical Science Foundation of China(Grant No.2019ZA037001)。
文摘An ultra-wideband bandpass filter(BPF)with a wide out-of-band rejection based on a surface plasmonic waveguide(SPW)slotline with ring grooves is designed and analyzed.A paired microstrip-to-slotline transition is designed for quasiTEM to TM mode conversion by using a microstrip line with a circular pad and the slotline with the same circular slot.The mode conversion between the TM and the surface plasmon polariton(SPP)mode is realized by using a gradient slotline with ring grooves and an impedance matching technique.The upper cut-off frequencies of the passband can be adjusted by using these proposed SPP units,while the lower frequencies of the passband are created by using the microstrip-toslotline transitions to give an ultra-wideband BPF.The dispersion curves of SPP units,electric field distribution,and the transmission spectra of the proposed ultra-wideband bandpass filter are all calculated and analyzed by the finite-difference time-domain(FDTD)method.The simulated results show that the presented filter has good performance including a wide3-dB bandwidth of 149%from 0.57 GHz to 3.93 GHz,an extremely wide 40-dB upper-band rejection from 4.2 GHz to18.5 GHz,and low loss and high selectivity in the passband.To prove the design validity,a prototype of the BPF has been manufactured and measured,showing a reasonable agreement with simulation results.The unique features of the proposed BPF may make it applicable for integrated circuit and plasmonic devices in microwave or THz frequency ranges.
基金Project supported by the National Natural Science Foundation of China(Grant No.11647021)the Fundamental Research Funds for the Central Universities of China(Grant No.ZY1531)
文摘The propagation length of surface plasmon polaritons（SPPs） is intrinsically limited by the metallic ohmic loss that is enhanced by the strongly confined electromagnetic field. In this paper, we propose a new class of hybrid plasmonic waveguides（HPWs） that can support long-range SPP propagation while keeping subwavelength optical field confinement. It is shown that the coupling between the waveguides can be well tuned by simply varying the structural parameters. Compared with conventional HPWs, a larger propagation length as well as a better optical field confinement can be simultaneously realized. The proposed structure with better optical performance can be useful for future photonic device design and optical integration research.
基金Project supported by the National Basic Research Program of China(Grant No.2013CBA01702)the National Natural Science Foundation of China(Grant Nos.61377016,61575055,10974039,61307072,61308017,and 61405056)
文摘According to the electromagnetic field distributions, there exist two kinds of coupled spoof surface plasmon polaritons（SSPPs）, the symmetric and anti-symmetric modes, in the three-dimensional（3D） subwavelength spoof–insulator–spoof（SIS） waveguide. We study the dispersion and excitation of the two kinds of coupled SSPPs supported by the 3D SIS waveguide. The evolution of the dispersion with the thickness and gap width of the waveguide is numerically investigated,and we give a theoretical analysis according to the coupling mechanism. Specially, based on the coupling mechanism,we design a zipper structure, through which the excitation and propagation of the anti-symmetric coupled modes can be realized effectively.
基金supported by Anhui University Natural Science Research Project,China(KJ2015A153)National Natural Science Foundation of China (11304002)
文摘A surface plasmon resonance(SPR)sensor with Ag/PbS/GR hybrid nanostructure has been proposed for the diagnostics of liquid phase samples.Here Ag/PbS/GR hybrid nanostructure is designed as an asymmetric MIM waveguide for surface plasmon.Due to the guided wave SPR(GWSPR)modes,the index of the liquid phase samples can be measured more accurately than the conventional SPR sensors.Numerical simulation results show that the sensitivity of the sensor is about 5 times higher than the conventional SPR sensors.The origin of the enhancement mechanism is the combination of GWSPR in the Ag/PbS/GR hybrid nanostructure which enables the surface plasmon to spread along the PbS layer.In Ag/PbS/GR hybrid nanostructure,the electric field is concentrated mostly in the PbS layer,and the enhancement of the field intensity is nearly30%.
基金Project supported by the National Basic Research Program of China(Grant No.2012CB921501)the National Natural Science Foundation of China(Grant Nos.11322439,11274165,11321063,and 91321312)+1 种基金the Dengfeng Project B of Nanjing University,Chinathe PAPD of Jiangsu Higher Education Institutions,China
文摘Surface plasmon polariton（SPP）, a sub-wavelength surface wave promising for photonic integration, always suffers from the large metallic loss that seriously restricts its practical application. Here, we propose a compact SPP amplifier based on a nonlinear hybrid waveguide（a combination of silver, LiNbO3, and SiO2）, where a couple of Bragg gratings are introduced in the waveguide to construct a cavity. This special waveguide is demonstrated to support a highly localized SPP-like hybrid mode and a low loss waveguide-like hybrid mode. To provide a large nonlinear gain, a pumping wave input from the LiNbO3 waveguide is designed to resonate inside the cavity and satisfy the cavity phase matching to fulfill the optical parametric amplification（OPA） of the SPP signal. Proper periods of gratings and the cavity length are chosen to satisfy the impedance matching condition to ensure the high input efficiency of the pump wave from the outside into the cavity. In theoretical calculations, this device demonstrates a high performance in a very compact scheme（~3.32 μm） and a much lower pumping power for OPA compared with single-pass pumping. To obtain a comprehensive insight into this cavity OPA, the influences of the pumping power, cavity length, and the initial phase are discussed in detail.
基金the National Natural Science Foundation of China(Grant Nos.11647122 and 61705064)the Natural Science Foundation of Hubei Province,China(Grant Nos.2018CFB672 and 2018CFB773).
文摘An ultrafast and low-power slow light tuning mechanism based on plasmon-induced transparency(PIT)for two disk cavities aperture-coupled to a metal-dielectric-metal plasmonic waveguide system is investigated numerically and analytically.The optical Kerr effect is enhanced by the local electromagnetic field of surface plasmon polaritons,slow light,and graphene-Ag composite material structures with a large effective Kerr nonlinear coefficient.Through the dynamic adjustment of the frequency of the disk nanocavity,the group velocity is controlled between c/53.2 and c/15.1 with the pump light intensity increased from 0.41 MW/cm^2 to 2.05 MW/cm^2.Alternatively,through the dynamic adjustment of the propagation phase of the plasmonic waveguide,the group velocity is controlled between c/2.8 and c/14.8 with the pump light intensity increased from 5.88 MW/cm^2 to 11.76 MW/cm^2.The phase shift multiplication of the PIT effect is observed.Calculation results indicate that the entire structure is ultracompact and has a footprint of less than 0.8μm^2.An ultrafast responsive time in the order of 1 ps is reached due to the ultrafast carrier relaxation dynamics of graphene.All findings are comprehensively analyzed through finite-difference time-domain simulations and with a coupling-mode equation system.The results can serve as a reference for the design and fabrication of nanoscale integration photonic devices with low power consumption and ultrafast nonlinear responses.
基金Supported by the National Basic Research Program of China under Grant Nos 2011CBA00200 and 2011CB921200the Strategic Priority Research Program(B)of the Chinese Academy of Sciences under Grant No XDB01030200+2 种基金the National Natural Science Foundation of China under Grant No 11374289the Fundamental Research Funds for the Central Universities under Grant No K2470000012the Program for New Century Excellent Talents in University
文摘In photonie integrated circuits, information is usually encoded in the optical path. In this work, based on the multi-mode dielectric-loaded surface plasmon polariton waveguide, we numerically design a directional coupler, which can divide the different waveguide eigenmodes into different optical paths. The results show a possibility to encode information onto different waveguide modes. We also experimentally demonstrate that the splitting ratio of this directional coupler structure can be tuned without changing its size.
文摘The large negative permittivity of noble metals in the infrared region prevents the possibility of highly confined plasmons in simple waveguide structures such as thin films or rods. This is a critical obstacle to applications of nonlinear plasmonics in the telecommunication wavelength region. We theoretically propose and numerically demonstrate that such limitation can be overcome by exploiting inter-element coupling effects in a plasmonic waveguide array. The supermodes of a plasmonic array span a large range of effective indices, making these structures ideal for broadband mode-multiplexed interconnects for integrated photonic devices. We show such plasmonic waveguide arrays can significantly enhance nonlinear optical interactions when operating in a high-index, tightly bound supermode. For example, a third-order nonlinear coeffident in such a waveguide can be more than three orders of magnitude larger compared to silicon waveguides of similar dimensions. These findings open new design possibilities towards the application of plasmonics in integrated optical devices in the telecommunications spectral region.
基金This study was financially supported by the National Natural Science Foundation of China(Grants 11374353,11204390 and 11274149)the Fundamental Research Funds for the Central Universities(CQDXWL-2013-009)+1 种基金the Program of Shenyang Key Laboratory of Optoelectronic Materials and Technology(F12-254-1-00)Special Fund for Agro-scientific Research in the Public Interest(NO.201303045).
文摘Due to its amazing ability to manipulate light at the nanoscale,plasmonics has become one of the most interesting topics in the field of light–matter interaction.As a promising application of plasmonics,surface-enhanced Raman scattering(SERS)has been widely used in scientific investigations and material analysis.The large enhanced Raman signals are mainly caused by the extremely enhanced electromagnetic field that results from localized surface plasmon polaritons.Recently,a novel SERS technology called remote SERS has been reported,combining both localized surface plasmon polaritons and propagating surface plasmon polaritons(PSPPs,or called plasmonic waveguide),which may be found in prominent applications in special circumstances compared to traditional local SERS.In this article,we review the mechanism of remote SERS and its development since it was first reported in 2009.Various remote metal systems based on plasmonic waveguides,such as nanoparticle–nanowire systems,single nanowire systems,crossed nanowire systems and nanowire dimer systems,are introduced,and recent novel applications,such as sensors,plasmon-driven surface-catalyzed reactions and Raman optical activity,are also presented.Furthermore,studies of remote SERS in dielectric and organic systems based on dielectric waveguides remind us that this useful technology has additional,tremendous application prospects that have not been realized in metal systems.
基金supported by the National Natural Science Foundation of China(Grant Nos.12064045,11364044 and 11864043)the Science and Technology Development Foundation of Jilin Province(Grant No.20180101342JC)Science and Technology Research Project of Education Department of Jilin Province(Grant No.JJKH20200509KJ).
文摘We demonstrate the possibility of dual-band unidirectional reflectionlessness in a non-Hermitian quantum system composed of a plasmonic waveguide and two end-coupled plasmonic cavities(PCs).Our scheme exhibits dual-band unidirectional reflectionlessness can be obtained at exceptional points by properly adjusting the coupling strength between two PCs,the ratio of decay rates of two PCs,and the ratio of plasmonic cavity-waveguide coupling strengths.As a valuable feature,the quality factor reaches to~175.4 in forward direction,while the backward quality factor is close to~188.2.
基金National Research Foundation of Korea(NRF)(NRF-2015R1A2A1A15055998,NRF-2013M3C1A3065051,NRF-2016R1C1B2007007)
文摘We suggest a low cross-talk plasmonic cross-connector based on a metal/insulator/metal cavity and waveguides.We separately investigate the isolated cavity mode, the waveguide mode, and the combination of cavity and waveguide modes using a finite-different time-domain method. Due to resonant tunneling and the cutoff frequency of the odd waveguide mode, our proposed structure achieves a high throughput transmission ratio and eliminates cross-talk. Furthermore, the proposed structure has a broadband tunability of 587 nm, which can be achieved by modulating the cavity air gap thickness. This structure enables the miniaturization of photonic integrated circuits and sensing applications.
基金This work was financially supported by the Russian Foundation for Basic Research(Grant No.16-29-09528_ofi_m)for numerical calculationsby the Ministry of Science and Higher Education within the State assignment FSRC《Crystallography and Photonics》RAS(Grant No.007-GZ/Ch3363/26)for theoretical results.
文摘We propose a polarization-insensitive design of a hybrid plasmonic waveguide(HPWG)optimized at the 3.392µm wavelength which corresponds to the absorption line of methane gas.The waveguide design is capable of providing high mode sensitivity(Smode)and evanescent field ratio(EFR)for both transverse electric(TE)and transverse magnetic(TM)hybrid modes.The modal analysis of the waveguide is performed via 2-dimension(2D)and 3-dimension(3D)finite element methods(FEMs).At optimized waveguide parameters,Smode and EFR of 0.94 and 0.704,can be obtained for the TE hybrid mode,respectively,whereas the TM hybrid mode can offer Smode and EFR of 0.86 and 0.67,respectively.The TE and TM hybrid modes power dissipation of~3 dB can be obtained for a 20-µm-long hybrid plasmonic waveguide at the 60%gas concentration.We believe that the highly sensitive waveguide scheme proposed in this work overcomes the limitation of the polarization controlled light and can be utilized in gas sensing applications.
基金supported by the National Natural Science Foundation of China(Nos.60908028,60971068,10979065,and 61275201)the Program for the New Century Excellent Talents in University(No.NCET10-0261)
文摘A nonlinear hybrid plasmonic slot waveguide composed of periodically poled lithium niobate(PPLN) and two separated silver films is investigated. The e?ective refractive index, propagation length, and energy confinement of the hybrid anti-symmetric mode in this waveguide are calculated using the structure parameters at the fundamental wavelength of λ = 1550 nm and its second harmonic(SH) λ = 775 nm. Through the above indices, coupling e?ciency(maximum SH conversion e?ciency during propagation) and peak position(propagation location of the conversion e?ciency) of SH generation are analyzed. Finally, higher conversion e?ciency can be achieved at a shorter propagation distance by changing the waveguide into a tapered structure.
