Mechanical metamaterials are artificial materials that control their macroscopic properties using repetitive units rather than chemical constituents.Through rational design and spatial arrangement of the unit cells,me...Mechanical metamaterials are artificial materials that control their macroscopic properties using repetitive units rather than chemical constituents.Through rational design and spatial arrangement of the unit cells,mechanical metamaterials can realize a range of counterintuitive properties on a larger scale.In this work,a type of mechanical metamaterial unit cell is proposed,exhibiting both compression-twist coupling behavior and bistability that can be programmed.The design involves linking two cylindrical frames with topology-designed inclined beams.Under uniaxial loading,the structure undergoes a compression-twist deformation,along with buckling at two joints of the inclined beams.Through a rational design of the unit's geometric parameters,the structure can retain its deformed state once the applied displacement surpasses a specified threshold,showing a programmed bistable characteristic.We investigated the influence of the involved parameters on the mechanical response of the unit cells numerically,which agrees well with our experimental results.Since the inclined beams dominate the elastic deformation of unit cells,the two cylindrical frames are almost independent of the bistable response and can therefore be designed in any shape for various arrangements of unit cells in multi-dimensional space.展开更多
The unique arrangement of panels and folds in origami structures provides distinct mechanical properties,such as the ability to achieve multiple stable states,reconfigure shapes,and adjust performance.However,combinin...The unique arrangement of panels and folds in origami structures provides distinct mechanical properties,such as the ability to achieve multiple stable states,reconfigure shapes,and adjust performance.However,combining movement and control functions into a simple yet efficient origami-based system remains a challenge.This study introduces a practical and efficient bistable origami mechanism,realized through lightweight and tailored designs in two bio-inspired applications.The mechanism is constructed from two thin materials:a PET sheet with precisely cut flexible hinges and a pre-tensioned elastic band.Its mechanical behavior is studied using nonlinear spring models.These components can be rearranged to create new bistable structures,enabling the integration of movement and partial control features.Inspired by natural systems,the mechanism is applied to two examples:a passive origami gripper that can quickly and precisely grasp moving objects in less than 100 ms,and an active magnetic-driven fish tail capable of high-speed swimming in multiple modes,reaching a maximum straight-line speed of 3.35 body lengths per second and a turning speed of 2.3 radians per second.This bistable origami mechanism highlights its potential for flexible design and high performance,offering useful insights for developing origami-based robotic systems.展开更多
The polarization switching（PS） and polarization bistability（PB） characteristics of a 1550-nm vertical-cavity surfaceemitting laser（VCSEL） subjected to orthogonal optical injection are systematically investigated...The polarization switching（PS） and polarization bistability（PB） characteristics of a 1550-nm vertical-cavity surfaceemitting laser（VCSEL） subjected to orthogonal optical injection are systematically investigated.The simulated results show that the PS and polarization-resolved nonlinear dynamical states of the VCSEL are critically dependent on the changing paths of the injected power.The polarization dynamics for different scanning directions of the injected power is presented to explain the polarization evolution during the formation of PS.In the case of forward scanning injected power,with the increase of frequency detuning level between the VCSEL and the injected light,the injected power required for PS gradually increases for negative frequency detuning but exhibits fluctuations for positive frequency detuning.In the case of reversely scanning injected power,the injected power required for PS displays fluctuant changes within the whole frequency detuning range.Specifically,PS may disappear under certain negative frequency detuning and large bias current.Furthermore,the hysteresis width as a function of the frequency detuning is calculated,and the regions for the appearance and disappearance of PB have been determined in the parameter space of the bias current and frequency detuning.展开更多
We investigate the tunable bistable behavior of a hybrid nano-electro-optomechanical system(NEOMS) composed of S-shaped in the presence of two-level atoms, trapped inside a Fabry–Pérot cavity, and driven by a st...We investigate the tunable bistable behavior of a hybrid nano-electro-optomechanical system(NEOMS) composed of S-shaped in the presence of two-level atoms, trapped inside a Fabry–Pérot cavity, and driven by a strong driving field and a weak probe field. The bistable behavior of the steady-state photon number and the mechanical steady-state positions are discussed. Further, we tune bistability by tuning all the coupling frequencies involved in the system and amplitude of the driving field. The present study provides the possibility of realization of a controllable optical switch depending on atom-field coupling, optomechanical coupling, electrostatic Coulomb coupling, and threshold power. In addition, we discuss that the non-linear effect of the hybrid NEOMS generates the four-wave mixing(FWM) process. Moreover, we show that the FWM process can be suppressed by the atom-field detuning and cavity-field detuning, which exhibits low photon transmission.展开更多
Optical bistability （0t3） and optical multi-stability （OM） of a four-level A-type atomic system with two fold lower levels inside a unidirectional ring cavity is investigated. The effect of quantum interference ar...Optical bistability （0t3） and optical multi-stability （OM） of a four-level A-type atomic system with two fold lower levels inside a unidirectional ring cavity is investigated. The effect of quantum interference arising from spontaneous emission and incoherent pumping on 013 and OM is discussed. It is found that the threshold of OB and OM can be controlled by quantum interference mechanisms. In addition intensity of coupling field and the rate of an incoherent pumping field on behavior of OB and OM are then discussed.展开更多
Under a nonresonant condition, we theoretically investigate hybrid absorptive-dispersive optical bistability and multistability behaviours in a three-level △-type system by using a microwave field to drive a hyperfin...Under a nonresonant condition, we theoretically investigate hybrid absorptive-dispersive optical bistability and multistability behaviours in a three-level △-type system by using a microwave field to drive a hyperfine transition between two upper excited states inside a unidirectional ring cavity. We find that the optical bistability and multistability behaviours can be controlled by adjusting the intensity of the microwave field or the intensity of the coherent coupling field. Furthermore, our studies show an interesting phenomenon of the transition from the optical bistability to the optical multistability only by changing the negative detuning of the coupling field into the positive detuning of the coupling field.展开更多
We theoretically investigate the Doppler effect on optical bistability in an N-type active Raman gain atomic system inside an optical ring cavity. It is shown that the Doppler effect can greatly enhance the dispersion...We theoretically investigate the Doppler effect on optical bistability in an N-type active Raman gain atomic system inside an optical ring cavity. It is shown that the Doppler effect can greatly enhance the dispersion and thus create the bistable behaviour or greatly increase the bistable region, which has been known as the positive Doppler effect on optical bistability. In addition, we find that a positive Doppler effect can change optical bistability from the hybrid dispersion-gain type to a dispersive type.展开更多
The main theorem of the present paper is the bistability theorem for a four dimensional cancer model, in the variables representing primary cancer C, metastatic cancer , growth factor GF and growth in...The main theorem of the present paper is the bistability theorem for a four dimensional cancer model, in the variables representing primary cancer C, metastatic cancer , growth factor GF and growth inhibitor GI, respectively. It says that for some values of the para- meters this system is bistable, in the sense that there are exactly two positive singular points of this vector field. And one is stable and the other unstable. We also find an expression for for the discrete model T of the introduction, with variables , where C is cancer, are growth factors and growth inhibitors respectively. We find an affine vector field Y whose time one map is T<sup>2</sup> and then compute , where is an integral curve of Y through . We also find a formula for the first escape time for the vector field associated to T, see section four.展开更多
We study the optical bistability for a Bose-Einstein condensate of atoms in a driven optical cavity with a Kerr medium. We find that both the threshold point of optical bistability transition and the width of optical ...We study the optical bistability for a Bose-Einstein condensate of atoms in a driven optical cavity with a Kerr medium. We find that both the threshold point of optical bistability transition and the width of optical bistability hysteresis can be controlled by appropriately adjusting the Kerr interaction between the photons. In particular, we show that the optical bistability will disappear when the Kerr interaction exceeds a critical value.展开更多
In this paper we investigate the nonlinear dynamics for optical bistabile(OB) model of homogeneously broadened two-level atomic medium interacting with a single mode of the ring cavity in the presence of a Kerr-nonlin...In this paper we investigate the nonlinear dynamics for optical bistabile(OB) model of homogeneously broadened two-level atomic medium interacting with a single mode of the ring cavity in the presence of a Kerr-nonlinear blackbody(KNB) radiation reservoir. We show the impact of the relative temperature of the reservoir on the transition between the dynamical states via bifurcation diagrams that represents the relation between maximum values of the output field and the relative temperature for fixed input field. Specifically, decreasing the relative temperature(T_b)causes the system to bifurcate from periodic to chaotic behavior and in turn reverts back to periodic behavior with further decrease of T_b. Varying atomic detuning leads to a change in the nature of the dynamic transition between the system's states from self pulsing to chaotic behavior.展开更多
The effects of optical field on the phenomenon of optical bistability(OB) are investigated in a K-type semiconductor double quantum well(SDQW) under various parametric conditions. It is shown that the OB threshold can...The effects of optical field on the phenomenon of optical bistability(OB) are investigated in a K-type semiconductor double quantum well(SDQW) under various parametric conditions. It is shown that the OB threshold can be manipulated by increasing the intensity of coupling field. The dependence of the shift of OB hysteresis curve on probe wavelength detuning is then explored. In order to demonstrate controllability of the OB in this SDQW, we compare the OB features of three different configurations which could arise in this SDQW scheme, i.e., K-type, Y-type, and inverted Y-type systems. The controllability of this semiconductor nanostructure medium makes the presented OB scheme more valuable for applications in all-optical switches, information storage, and logic circuits of all optical information processing.展开更多
We report some new results associated with the synchronization behavior of two coupled double-well Duffing oscillators （DDOs）. Some sufficient algebraic criteria for global chaos synchronization of the drive and res...We report some new results associated with the synchronization behavior of two coupled double-well Duffing oscillators （DDOs）. Some sufficient algebraic criteria for global chaos synchronization of the drive and response DDOs via linear state error feedback control are obtained by means of Lyapunov stability theory. The synchronization is achieved through a bistable state in which a periodic attractor co-exists with a chaotic attractor. Using the linear perturbation analysis, the prevalence of attractors in parameter space and the associated bifurcations are examined. Subcritical and supercritical Hopf bifurcations and abundance of Arnold tongues -- a signature of mode locking phenomenon are found.展开更多
Bistability behaviors in an optical ring cavity filled with a dense V-type four-level atomic medium are theoretically investigated. It is found that the optical bistability can appear in the negative refraction freque...Bistability behaviors in an optical ring cavity filled with a dense V-type four-level atomic medium are theoretically investigated. It is found that the optical bistability can appear in the negative refraction frequency band, while both the bistability and multi-stability can occur in the positive refraction frequency bands. Therefore, optical bistability can be realized from conventional material to negative index material due to quantum coherence in our scheme.展开更多
Role of Fano interference and incoherent pumping field on optical bistability in a four-level designed InGaN/GaN quantum dot nanostructure embedded in a unidirectional ring cavity are analyzed. It is found that intens...Role of Fano interference and incoherent pumping field on optical bistability in a four-level designed InGaN/GaN quantum dot nanostructure embedded in a unidirectional ring cavity are analyzed. It is found that intensity threshold of optical bistability can be manipulated by Fano interference. It is shown that incoherent pumping fields make the threshold of optical bistability behave differently by Fano interference. Moreover, in the presence of Fano interference the medium becomes phase-dependent. Therefore, the relative phase of applied fields can affect the behaviors of optical bistability and intensity threshold can be controlled easily.展开更多
Luminescent spin crossover(SCO) materials have attracted significant interest owing to their potential applications in magneto-optical switches. However, the majority of previously reported FeII-based SCO complexes ar...Luminescent spin crossover(SCO) materials have attracted significant interest owing to their potential applications in magneto-optical switches. However, the majority of previously reported FeII-based SCO complexes are adversely affected by fluorescence quenching in the solid-state. Here, we have constructed the first mononuclear FeIIcomplex decorated with an aggregation-induced emission(AIE) luminophore(i.e., tetraphenylethylene) that exhibits synergistic SCO and fluorescence behavior. Intriguingly, we obtained two types of crystals in different solvent systems, both displaying distinct magnetic bistability and fluorescence properties. The fluorescence intensity was observed to track the magnetic susceptibility, which confirmed that SCO and solid-state fluorescence operate synergistically. We introduce a novel approach for the construction of luminescent SCO compounds using an AIEgen as a luminophore, which leads to fluorescence emission in the solid-state, thus allowing us to study the synergy between SCO and fluorescence.展开更多
The first-order-like phase transition (FOLT) in the dispersive optical bistability is investigated when the fluctuation in the incident light field is considered as colored noise. A unified colored-noise approximation...The first-order-like phase transition (FOLT) in the dispersive optical bistability is investigated when the fluctuation in the incident light field is considered as colored noise. A unified colored-noise approximation is applied to obtain the steady state distribution (SSD) when either the intensity or phase fluctuations of the incident field are included in the system. For intensity fluctuations only, the curve of SSD is changed from single extreme to two extremes, and then to three extremes. The colored nature of the noise can reduce the fluctuation in the system. However, for phase fluctuations only, the FOLT is mainly induced by the colored nature of the noise. The curve of SSD is changed from single extreme to three extremes directly. There is no FOLT existing for white noise.展开更多
It is proposed that a segment of Er doped fiber with a couple of fiber gratings on the ends may be used as a novel optical bistability device with low power and high speed. Operation and bistability threshold of devi...It is proposed that a segment of Er doped fiber with a couple of fiber gratings on the ends may be used as a novel optical bistability device with low power and high speed. Operation and bistability threshold of device are analysed in accordance with the distributed feedback couple mode theory and the nonlinear characteristic of Er doped fiber. It is shown that a nanoseconds microwatts bistable operation of a centimeter device is realizable under nowaday technological condition.展开更多
A composite system consisting of a degenerate optical parametric oscillator （DOPO） and N two-level atoms interacting with a broadband squeezed vacuum （SV） centred at frequency cas and an input monochromatic pumpin...A composite system consisting of a degenerate optical parametric oscillator （DOPO） and N two-level atoms interacting with a broadband squeezed vacuum （SV） centred at frequency cas and an input monochromatic pumping field with a frequency ωp is analysed. The corresponding explicit analytical steady-state solutions in the central mode ωp = ωs are derived, and the result displays optical bistability （OB）. In addition, the influence of the broadband SV on the bistable behaviour is analysed in detail.展开更多
In this paper we investigate the optical properties of an open four-level tripod atomic system driven by an elliptically polarized probe field and compare its properties with the corresponding closed system. Our resul...In this paper we investigate the optical properties of an open four-level tripod atomic system driven by an elliptically polarized probe field and compare its properties with the corresponding closed system. Our results reveal that absorption,dispersion, group velocity, and optical bistability of the probe field can be manipulated by adjusting the phase difference between the two circularly polarized components of a single coherent field and cavity parameters, i.e., the atomic exit rate from cavity and atomic injection rates.展开更多
We discuss the influences of two different types of mechanisms of quantum coherence on optical bistability in a semiconductor quantum well structure.In the first mechanism,only quantum coherence induced by the resonan...We discuss the influences of two different types of mechanisms of quantum coherence on optical bistability in a semiconductor quantum well structure.In the first mechanism,only quantum coherence induced by the resonant coupling of a strong control laser is considered.In the second mechanism,the decay coherence is taken into account under the condition where the control field is weak.In two different cases,optical bistability can be obtained through choosing appropriate physical parameters.Our studies show quantum coherence makes the optical nonlinear effect of the system become stronger,which takes an important role in the process of generating optical bistability.A semiconductor quantum well with flexibility and easy integration in design could potentially be exploited in real solid-state devices.展开更多
基金supported by the National Natural Science Foundation of China(Grant Numbers:12125205,12321002,12072316,12132014)the Zhejiang Provincial Natural Science Foundation of China(LD22A020001).
文摘Mechanical metamaterials are artificial materials that control their macroscopic properties using repetitive units rather than chemical constituents.Through rational design and spatial arrangement of the unit cells,mechanical metamaterials can realize a range of counterintuitive properties on a larger scale.In this work,a type of mechanical metamaterial unit cell is proposed,exhibiting both compression-twist coupling behavior and bistability that can be programmed.The design involves linking two cylindrical frames with topology-designed inclined beams.Under uniaxial loading,the structure undergoes a compression-twist deformation,along with buckling at two joints of the inclined beams.Through a rational design of the unit's geometric parameters,the structure can retain its deformed state once the applied displacement surpasses a specified threshold,showing a programmed bistable characteristic.We investigated the influence of the involved parameters on the mechanical response of the unit cells numerically,which agrees well with our experimental results.Since the inclined beams dominate the elastic deformation of unit cells,the two cylindrical frames are almost independent of the bistable response and can therefore be designed in any shape for various arrangements of unit cells in multi-dimensional space.
基金supported in part by the Fundamental Research Funds for the Central Universities under Grant CSA-TS202404in part by the National Natural Science Foundation of China under Grant 12172226.
文摘The unique arrangement of panels and folds in origami structures provides distinct mechanical properties,such as the ability to achieve multiple stable states,reconfigure shapes,and adjust performance.However,combining movement and control functions into a simple yet efficient origami-based system remains a challenge.This study introduces a practical and efficient bistable origami mechanism,realized through lightweight and tailored designs in two bio-inspired applications.The mechanism is constructed from two thin materials:a PET sheet with precisely cut flexible hinges and a pre-tensioned elastic band.Its mechanical behavior is studied using nonlinear spring models.These components can be rearranged to create new bistable structures,enabling the integration of movement and partial control features.Inspired by natural systems,the mechanism is applied to two examples:a passive origami gripper that can quickly and precisely grasp moving objects in less than 100 ms,and an active magnetic-driven fish tail capable of high-speed swimming in multiple modes,reaching a maximum straight-line speed of 3.35 body lengths per second and a turning speed of 2.3 radians per second.This bistable origami mechanism highlights its potential for flexible design and high performance,offering useful insights for developing origami-based robotic systems.
基金supported by the National Natural Science Foundation of China(Grant Nos.61178011,61275116,and 61475127)the Natural Science Foundation of Chongqing City,China(Grant No.2012jjB40011)
文摘The polarization switching（PS） and polarization bistability（PB） characteristics of a 1550-nm vertical-cavity surfaceemitting laser（VCSEL） subjected to orthogonal optical injection are systematically investigated.The simulated results show that the PS and polarization-resolved nonlinear dynamical states of the VCSEL are critically dependent on the changing paths of the injected power.The polarization dynamics for different scanning directions of the injected power is presented to explain the polarization evolution during the formation of PS.In the case of forward scanning injected power,with the increase of frequency detuning level between the VCSEL and the injected light,the injected power required for PS gradually increases for negative frequency detuning but exhibits fluctuations for positive frequency detuning.In the case of reversely scanning injected power,the injected power required for PS displays fluctuant changes within the whole frequency detuning range.Specifically,PS may disappear under certain negative frequency detuning and large bias current.Furthermore,the hysteresis width as a function of the frequency detuning is calculated,and the regions for the appearance and disappearance of PB have been determined in the parameter space of the bias current and frequency detuning.
文摘We investigate the tunable bistable behavior of a hybrid nano-electro-optomechanical system(NEOMS) composed of S-shaped in the presence of two-level atoms, trapped inside a Fabry–Pérot cavity, and driven by a strong driving field and a weak probe field. The bistable behavior of the steady-state photon number and the mechanical steady-state positions are discussed. Further, we tune bistability by tuning all the coupling frequencies involved in the system and amplitude of the driving field. The present study provides the possibility of realization of a controllable optical switch depending on atom-field coupling, optomechanical coupling, electrostatic Coulomb coupling, and threshold power. In addition, we discuss that the non-linear effect of the hybrid NEOMS generates the four-wave mixing(FWM) process. Moreover, we show that the FWM process can be suppressed by the atom-field detuning and cavity-field detuning, which exhibits low photon transmission.
文摘Optical bistability （0t3） and optical multi-stability （OM） of a four-level A-type atomic system with two fold lower levels inside a unidirectional ring cavity is investigated. The effect of quantum interference arising from spontaneous emission and incoherent pumping on 013 and OM is discussed. It is found that the threshold of OB and OM can be controlled by quantum interference mechanisms. In addition intensity of coupling field and the rate of an incoherent pumping field on behavior of OB and OM are then discussed.
基金supported by Natural Science Foundation of Jiangxi,China (Grant Nos 2007GZW0819 and 2008GQW0017)the Scientific Research Foundation of Jiangxi Provincial Department of Education,China (Grant Nos [2007]191 and GJJ09504)+1 种基金the Science Foundation of East China Jiaotong University of China (Grant No 06ZKJC01)the Foundation of Talent of Jinggang of Jiangxi Province of China
文摘Under a nonresonant condition, we theoretically investigate hybrid absorptive-dispersive optical bistability and multistability behaviours in a three-level △-type system by using a microwave field to drive a hyperfine transition between two upper excited states inside a unidirectional ring cavity. We find that the optical bistability and multistability behaviours can be controlled by adjusting the intensity of the microwave field or the intensity of the coherent coupling field. Furthermore, our studies show an interesting phenomenon of the transition from the optical bistability to the optical multistability only by changing the negative detuning of the coupling field into the positive detuning of the coupling field.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60978013)the Shanghai Rising Star Project,China (Grant No. 11QA1407400)
文摘We theoretically investigate the Doppler effect on optical bistability in an N-type active Raman gain atomic system inside an optical ring cavity. It is shown that the Doppler effect can greatly enhance the dispersion and thus create the bistable behaviour or greatly increase the bistable region, which has been known as the positive Doppler effect on optical bistability. In addition, we find that a positive Doppler effect can change optical bistability from the hybrid dispersion-gain type to a dispersive type.
文摘The main theorem of the present paper is the bistability theorem for a four dimensional cancer model, in the variables representing primary cancer C, metastatic cancer , growth factor GF and growth inhibitor GI, respectively. It says that for some values of the para- meters this system is bistable, in the sense that there are exactly two positive singular points of this vector field. And one is stable and the other unstable. We also find an expression for for the discrete model T of the introduction, with variables , where C is cancer, are growth factors and growth inhibitors respectively. We find an affine vector field Y whose time one map is T<sup>2</sup> and then compute , where is an integral curve of Y through . We also find a formula for the first escape time for the vector field associated to T, see section four.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11065005 and 11105079)the Governor’s Foundation for Science and Education Elites of Guizhou Province, China
文摘We study the optical bistability for a Bose-Einstein condensate of atoms in a driven optical cavity with a Kerr medium. We find that both the threshold point of optical bistability transition and the width of optical bistability hysteresis can be controlled by appropriately adjusting the Kerr interaction between the photons. In particular, we show that the optical bistability will disappear when the Kerr interaction exceeds a critical value.
文摘In this paper we investigate the nonlinear dynamics for optical bistabile(OB) model of homogeneously broadened two-level atomic medium interacting with a single mode of the ring cavity in the presence of a Kerr-nonlinear blackbody(KNB) radiation reservoir. We show the impact of the relative temperature of the reservoir on the transition between the dynamical states via bifurcation diagrams that represents the relation between maximum values of the output field and the relative temperature for fixed input field. Specifically, decreasing the relative temperature(T_b)causes the system to bifurcate from periodic to chaotic behavior and in turn reverts back to periodic behavior with further decrease of T_b. Varying atomic detuning leads to a change in the nature of the dynamic transition between the system's states from self pulsing to chaotic behavior.
基金supported by the Lithuanian Research Council(Grant No.VP1-3.1-M-01-V-03-001)
文摘The effects of optical field on the phenomenon of optical bistability(OB) are investigated in a K-type semiconductor double quantum well(SDQW) under various parametric conditions. It is shown that the OB threshold can be manipulated by increasing the intensity of coupling field. The dependence of the shift of OB hysteresis curve on probe wavelength detuning is then explored. In order to demonstrate controllability of the OB in this SDQW, we compare the OB features of three different configurations which could arise in this SDQW scheme, i.e., K-type, Y-type, and inverted Y-type systems. The controllability of this semiconductor nanostructure medium makes the presented OB scheme more valuable for applications in all-optical switches, information storage, and logic circuits of all optical information processing.
基金supported by a fellowship of the Alexander von Humboldt Foundation in Bonn, Germanythe Royal Society of London, British Academy and Physical Sciences Research Council, UK, under the Newton International Fellowship scheme.
文摘We report some new results associated with the synchronization behavior of two coupled double-well Duffing oscillators （DDOs）. Some sufficient algebraic criteria for global chaos synchronization of the drive and response DDOs via linear state error feedback control are obtained by means of Lyapunov stability theory. The synchronization is achieved through a bistable state in which a periodic attractor co-exists with a chaotic attractor. Using the linear perturbation analysis, the prevalence of attractors in parameter space and the associated bifurcations are examined. Subcritical and supercritical Hopf bifurcations and abundance of Arnold tongues -- a signature of mode locking phenomenon are found.
基金Project supported by the Fundamental Research Funds for the Central University (Grant Nos.GK201002024 and GK201003003)the National Natural Science Foundation of China (Grant Nos.11104176 and 11104185)+2 种基金the Natural Science Foundation of Shaanxi Province,China (Grant No.2011JQ1008)the Special Fund of Shanghai Outstanding Young Teachers,China (Grant Nos.slg10054 and slg10023)the Innovation Program of Shanghai Municipal Education Commission,China (Grant No.11YZ118)
文摘Bistability behaviors in an optical ring cavity filled with a dense V-type four-level atomic medium are theoretically investigated. It is found that the optical bistability can appear in the negative refraction frequency band, while both the bistability and multi-stability can occur in the positive refraction frequency bands. Therefore, optical bistability can be realized from conventional material to negative index material due to quantum coherence in our scheme.
文摘Role of Fano interference and incoherent pumping field on optical bistability in a four-level designed InGaN/GaN quantum dot nanostructure embedded in a unidirectional ring cavity are analyzed. It is found that intensity threshold of optical bistability can be manipulated by Fano interference. It is shown that incoherent pumping fields make the threshold of optical bistability behave differently by Fano interference. Moreover, in the presence of Fano interference the medium becomes phase-dependent. Therefore, the relative phase of applied fields can affect the behaviors of optical bistability and intensity threshold can be controlled easily.
基金Nankai University for the startup funds in support of young talented researcherssupported by the National Natural Science Foundation of China(NSFC, Nos. 21971124, 22035003)。
文摘Luminescent spin crossover(SCO) materials have attracted significant interest owing to their potential applications in magneto-optical switches. However, the majority of previously reported FeII-based SCO complexes are adversely affected by fluorescence quenching in the solid-state. Here, we have constructed the first mononuclear FeIIcomplex decorated with an aggregation-induced emission(AIE) luminophore(i.e., tetraphenylethylene) that exhibits synergistic SCO and fluorescence behavior. Intriguingly, we obtained two types of crystals in different solvent systems, both displaying distinct magnetic bistability and fluorescence properties. The fluorescence intensity was observed to track the magnetic susceptibility, which confirmed that SCO and solid-state fluorescence operate synergistically. We introduce a novel approach for the construction of luminescent SCO compounds using an AIEgen as a luminophore, which leads to fluorescence emission in the solid-state, thus allowing us to study the synergy between SCO and fluorescence.
文摘The first-order-like phase transition (FOLT) in the dispersive optical bistability is investigated when the fluctuation in the incident light field is considered as colored noise. A unified colored-noise approximation is applied to obtain the steady state distribution (SSD) when either the intensity or phase fluctuations of the incident field are included in the system. For intensity fluctuations only, the curve of SSD is changed from single extreme to two extremes, and then to three extremes. The colored nature of the noise can reduce the fluctuation in the system. However, for phase fluctuations only, the FOLT is mainly induced by the colored nature of the noise. The curve of SSD is changed from single extreme to three extremes directly. There is no FOLT existing for white noise.
文摘It is proposed that a segment of Er doped fiber with a couple of fiber gratings on the ends may be used as a novel optical bistability device with low power and high speed. Operation and bistability threshold of device are analysed in accordance with the distributed feedback couple mode theory and the nonlinear characteristic of Er doped fiber. It is shown that a nanoseconds microwatts bistable operation of a centimeter device is realizable under nowaday technological condition.
基金Project supported in part by the National Natural Science Foundation of China （Grant Nos 10125419 and 60478029）.
文摘A composite system consisting of a degenerate optical parametric oscillator （DOPO） and N two-level atoms interacting with a broadband squeezed vacuum （SV） centred at frequency cas and an input monochromatic pumping field with a frequency ωp is analysed. The corresponding explicit analytical steady-state solutions in the central mode ωp = ωs are derived, and the result displays optical bistability （OB）. In addition, the influence of the broadband SV on the bistable behaviour is analysed in detail.
文摘In this paper we investigate the optical properties of an open four-level tripod atomic system driven by an elliptically polarized probe field and compare its properties with the corresponding closed system. Our results reveal that absorption,dispersion, group velocity, and optical bistability of the probe field can be manipulated by adjusting the phase difference between the two circularly polarized components of a single coherent field and cavity parameters, i.e., the atomic exit rate from cavity and atomic injection rates.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11165008 and 11065007)the Natural Science Foundation of Jiangxi Province,China (Grant Nos. 20114BAB202001 and 2010GQW0011)the Science Foundation of East China Jiaotong University,China (Grant No. 10JC03)
文摘We discuss the influences of two different types of mechanisms of quantum coherence on optical bistability in a semiconductor quantum well structure.In the first mechanism,only quantum coherence induced by the resonant coupling of a strong control laser is considered.In the second mechanism,the decay coherence is taken into account under the condition where the control field is weak.In two different cases,optical bistability can be obtained through choosing appropriate physical parameters.Our studies show quantum coherence makes the optical nonlinear effect of the system become stronger,which takes an important role in the process of generating optical bistability.A semiconductor quantum well with flexibility and easy integration in design could potentially be exploited in real solid-state devices.
