Coherent perfect absorption provides a method of light-controlling-light and has practical applications in optical communications. Recently, a cavity-based nonlinear perfect photon absorption extends the coherent perf...Coherent perfect absorption provides a method of light-controlling-light and has practical applications in optical communications. Recently, a cavity-based nonlinear perfect photon absorption extends the coherent perfect absorber(CPA)beyond the linear regime. As nanowire-based system is a more competitive candidate for full-optical device, we introduce a nonlinear CPA in the single two-level atom–nanowires coupling system in this work. Nonlinear input–output relations are derived analytically, and three contributions of atomic saturation nonlinearity are explicit. The consociation of optical nonlinearity and destructive interference makes it feasible to fabricate a nonlinear monoatomic CPA. Our results also indicate that a nonlinear system may work linearly even when the incoming lights are not weak any more. Our findings show promising applications in full-optical devices.展开更多
A nonlinear torsional absorber,which can overcome the influence of the fluid velocity on the natural frequency,is employed at the boundary to restrain the bending vibration of a pipe for the first time.By using the ro...A nonlinear torsional absorber,which can overcome the influence of the fluid velocity on the natural frequency,is employed at the boundary to restrain the bending vibration of a pipe for the first time.By using the rotating angle at the end of the pipe,the bending vibration energy is pumped to the boundary absorber.The nonlinearly coupled pipe-absorber governing equations are obtained by the generalized Hamilton’s principle.Steady-state responses subjected to a basement excitation are discussed by the modal-correction-harmonic-balance-method.According to this method,the boundaries of the pipe are treated as the generalized governing equations.In this way,those nonlinearities and time-dependent terms in the boundary are involved in the response completely.A direct simulation method,called the differential quadrature element method(DQEM),is used to verify these analytical results.The investigation indicates that the nonlinear boundary absorber owns two outstanding advantages.The first one is that the natural characters remain the same and the absorber can capture the resonance of the pipe automatically.The second one is that the absorber works at all natural modes.Especially,by using the nonlinear damping,the absorber will not worsen the weak vibration in the non-resonance region.The parameters of the absorber are investigated to optimize the efficiency in detail.The result finds that good efficiency can be achieved with a tiny mass.Meanwhile,the efficiency becomes better as the damping increases.With the help of these investigations,the work provides a new strategy to protect pipes conveying fluids from being destroyed by the vibration.展开更多
We investigate the nonlinear response of terahertz(THz) metamaterial perfect absorbers consisting of electric split ring resonators on GaAs integrated with a polyimide spacer and gold ground plane. These perfect absor...We investigate the nonlinear response of terahertz(THz) metamaterial perfect absorbers consisting of electric split ring resonators on GaAs integrated with a polyimide spacer and gold ground plane. These perfect absorbers on bulk semi-insulating GaAs are characterized using high-field THz time-domain spectroscopy. The resonance frequency redshifts 20 GHz and the absorbance is reduced by 30% as the incident peak field is increased from 30 to 300 kV/cm. The nonlinear response arises from THz field driven interband transitions and intervalley scattering in the GaAs. To eliminate the Fresnel losses from the GaAs substrate, we design and fabricate a flexible metamaterial saturable perfect absorber. The ability to create nonlinear absorbers enables appealing applications such as optical limiting and self-focusing.展开更多
The development of responsive metamaterials has enabled the realization of compact tunable photonic devices capable of manipulating the amplitude,polarization,wave vector and frequency of light.Integration of semicond...The development of responsive metamaterials has enabled the realization of compact tunable photonic devices capable of manipulating the amplitude,polarization,wave vector and frequency of light.Integration of semiconductors into the active regions of metallic resonators is a proven approach for creating nonlinear metamaterials through optoelectronic control of the semiconductor carrier density.Metal-free subwavelength resonant semiconductor structures offer an alternative approach to create dynamic metamaterials.We present InAs plasmonic disk arrays as a viable resonant metamaterial at terahertz frequencies.Importantly,InAs plasmonic disks exhibit a strong nonlinear response arising from electric field-induced intervalley scattering,resulting in a reduced carrier mobility thereby damping the plasmonic response.We demonstrate nonlinear perfect absorbers configured as either optical limiters or saturable absorbers,including flexible nonlinear absorbers achieved by transferring the disks to polyimide films.Nonlinear plasmonic metamaterials show potential for use in ultrafast terahertz(THz)optics and for passive protection of sensitive electromagnetic devices.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11864018 and 11574229)Scientific Research Foundation of the Education Department of Jiangxi Province of China(Grant No.GJJ170645)Doctor Startup Fund of the Natural Science of Jinggangshan University,China(Grant No.JZB16003)
文摘Coherent perfect absorption provides a method of light-controlling-light and has practical applications in optical communications. Recently, a cavity-based nonlinear perfect photon absorption extends the coherent perfect absorber(CPA)beyond the linear regime. As nanowire-based system is a more competitive candidate for full-optical device, we introduce a nonlinear CPA in the single two-level atom–nanowires coupling system in this work. Nonlinear input–output relations are derived analytically, and three contributions of atomic saturation nonlinearity are explicit. The consociation of optical nonlinearity and destructive interference makes it feasible to fabricate a nonlinear monoatomic CPA. Our results also indicate that a nonlinear system may work linearly even when the incoming lights are not weak any more. Our findings show promising applications in full-optical devices.
基金supported by the National Natural Science Foundation of China(Grant Nos.12025204 and 11872159)the Program of Shanghai Municipal Education Commission(Grant No.2019-01-07-00-09-E00018)。
文摘A nonlinear torsional absorber,which can overcome the influence of the fluid velocity on the natural frequency,is employed at the boundary to restrain the bending vibration of a pipe for the first time.By using the rotating angle at the end of the pipe,the bending vibration energy is pumped to the boundary absorber.The nonlinearly coupled pipe-absorber governing equations are obtained by the generalized Hamilton’s principle.Steady-state responses subjected to a basement excitation are discussed by the modal-correction-harmonic-balance-method.According to this method,the boundaries of the pipe are treated as the generalized governing equations.In this way,those nonlinearities and time-dependent terms in the boundary are involved in the response completely.A direct simulation method,called the differential quadrature element method(DQEM),is used to verify these analytical results.The investigation indicates that the nonlinear boundary absorber owns two outstanding advantages.The first one is that the natural characters remain the same and the absorber can capture the resonance of the pipe automatically.The second one is that the absorber works at all natural modes.Especially,by using the nonlinear damping,the absorber will not worsen the weak vibration in the non-resonance region.The parameters of the absorber are investigated to optimize the efficiency in detail.The result finds that good efficiency can be achieved with a tiny mass.Meanwhile,the efficiency becomes better as the damping increases.With the help of these investigations,the work provides a new strategy to protect pipes conveying fluids from being destroyed by the vibration.
基金supported in part by the National Science Foundation under contract ECCS 1309835the DOE Basic Energy Sciences under Grant No.DE-SC0012592
文摘We investigate the nonlinear response of terahertz(THz) metamaterial perfect absorbers consisting of electric split ring resonators on GaAs integrated with a polyimide spacer and gold ground plane. These perfect absorbers on bulk semi-insulating GaAs are characterized using high-field THz time-domain spectroscopy. The resonance frequency redshifts 20 GHz and the absorbance is reduced by 30% as the incident peak field is increased from 30 to 300 kV/cm. The nonlinear response arises from THz field driven interband transitions and intervalley scattering in the GaAs. To eliminate the Fresnel losses from the GaAs substrate, we design and fabricate a flexible metamaterial saturable perfect absorber. The ability to create nonlinear absorbers enables appealing applications such as optical limiting and self-focusing.
基金supported in part by the National Science Foundation under contract ECCS 1309835the Air Force Office of Scientific Research under contract FA9550-09-1-0708+1 种基金support from DOEBasic Energy Sciences under Grant No.DE-FG02-09ER46643,under which the THz measurements were performedsupported by a Multidisciplinary University Research Initiative from the Air Force Office of Scientific Research(AFOSR MURI Award No.FA9550-12-1-0488)。
文摘The development of responsive metamaterials has enabled the realization of compact tunable photonic devices capable of manipulating the amplitude,polarization,wave vector and frequency of light.Integration of semiconductors into the active regions of metallic resonators is a proven approach for creating nonlinear metamaterials through optoelectronic control of the semiconductor carrier density.Metal-free subwavelength resonant semiconductor structures offer an alternative approach to create dynamic metamaterials.We present InAs plasmonic disk arrays as a viable resonant metamaterial at terahertz frequencies.Importantly,InAs plasmonic disks exhibit a strong nonlinear response arising from electric field-induced intervalley scattering,resulting in a reduced carrier mobility thereby damping the plasmonic response.We demonstrate nonlinear perfect absorbers configured as either optical limiters or saturable absorbers,including flexible nonlinear absorbers achieved by transferring the disks to polyimide films.Nonlinear plasmonic metamaterials show potential for use in ultrafast terahertz(THz)optics and for passive protection of sensitive electromagnetic devices.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.11572182,and 11772181)the China Scholarship Council(XL),and the Innovation Program of the Shanghai Municipal Education Commission(Grant No.2019-01-07-00-09-E00018)This support made possible the academic visit of Xiang Li to the University of Illinois and is gratefully acknowledged.