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Bistability in the current–voltage characteristics of semiconductor superlattices and quantum cascade laser structures has the potential for wide-ranging applications, particularly in sensing systems. However, the interdependency of applied bias and current injection in conventional two-terminal structures has led to complications in analysis and rendered the bistability phenomenon difficult to implement in practical applications. Here, we report a new kind of electronic bistability coupled to optical switching in a resonant tunneling bipolar superlattice transistor. This bistability manifests as sharp discontinuities in the collector current with extremely small variations of the applied voltage, which arise from unstable tunneling transmission across the hetero-barrier between the two-dimensional electron gas (2DEG) at the edge of the transistor base and the collector superlattice structure. The electronic transitions between high and low quantum mechanical transmissions are demonstrated to be caused by self-consistent variations of the internal electric field at the heterointerface between the 2DEG and the superlattice. They are also present in the base current of the three-terminal device and result in sharp switching of near-infrared spontaneous light emission output from an interband radiative recombination process with a peak emission wavelength of 1.58 μ m. A comprehensive quantum mechanical theoretical model accounting for the self-consistent bistable tunneling transmission is in quantitative agreement with the experimental data. The measured peak transconductance sensitivity value of 6000 mS can be used in the highly sensitive detector and non-linear device applications. [ABSTRACT FROM AUTHOR]

Optical bistability is investigated for optomechanical system composed of an ensemble of inhomogeneously broadened two-level atoms embedded between the two mirrors of the optical cavity, that is subjected to two input (strong and probe) fields. We consider two types of inhomogeneous broadened distributions, namely, Lorentzian and Gaussian line shapes. The first order harmonic components of the output fields (due to the presence of probe field) show reversed and knotted bistability shapes simultaneously with the standard bistable shape of the fundamental component of the field at frequency ω c . The inhomogeneous broadened line width for both Lorentzian and Gaussian distribution affects the dispersive switching of the system, as well as the bistable behavior. Locations of the maxima of photon numbers associated with higher harmonics of the output fields are identified with respect to the probe field frequency. [ABSTRACT FROM AUTHOR]

We present a theoretical study on optical bistability (OB), optical multistability (OM), and all-optical switching in a four-level Y-type atomic system. The density matrix formalism is used to derive the Optical Bloch equations in order to find out the response of the probe laser field. The characteristics of OB and OM have been studied under unidirectional ring cavity configuration. The line parameters of D1 transition of 87Rb isotope have been used in the simulation. The system exhibits OM without consideration of any additional coherence effect like spontaneously generated coherence in the theoretical formalism. Threshold intensities and hysteresis widths of OB as well as OM can be effectively tuned by varying the intensity and frequency detuning of the coherent fields. Dynamic control of the probe laser pulse propagating through the medium has been investigated. We also demonstrate the conversion of a continuous wave input probe field into output switched pulse. The ON/OFF time of the switched probe pulse can also be controlled by tuning the field parameters. Such a system would be very useful in designing all-optical switching devices and optical storage devices. [ABSTRACT FROM AUTHOR]

In this study, we theoretically study the optical bistability (OB) of reflected light beams at visible light frequencies by using a Kretschmann–Raether (KR) configuration where double-layer MoS2 is inserted. This OB phenomenon results from the local field enhancement owing to the excitation of metal surface plasmon polaritons (SPPs) and the introduction of the double-layer MoS2. By considering the third-order conductivity of MoS2, we obtain a threshold electric field with an incident electric field of 107 V/m levels. Furthermore, the influences of the structural parameters on the hysteretic behavior as well as the threshold of OB are clarified. This tunable OB phenomenon will provide possible options for nonlinear optical bistable devices. [ABSTRACT FROM AUTHOR]

The optical bistable characteristics of an optomechanical ring cavity containing a two-level atomic ensemble and Coulomb interaction between a cavity mirror and an external nanoresonator are theoretically investigated. Dynamics of the hybrid systems is actuated by Heisenberg–Langevin equations of motion. We derive the mean photon number equation and study the steady-state solution behavior. The optomechanical ring cavity exhibits the optical bistability by selecting appropriate parameters. In addition, we investigate the effect of parameters on optical bistability. The optical bistability threshold and the width of the optical bistability curve can be controlled by adjusting the vibration frequencies of the movable mirrors, the two-level atomic ensemble coupling strength, Coulomb interaction coupling strength between a cavity mirror and an external nanoresonator and the cavity decay rate. [ABSTRACT FROM AUTHOR]

We investigated optical bistability and its temperature dependence in a composite system composed of an all-superconducting photonic crystal and graphene. The photonic crystal, constructed from two types of superconducting sheets, and which is temperature-sensitive and can greatly localize the electric field, alternately supports a defect mode in a cryogenic environment. Graphene is located at the strongest site in the electric field, so the third-order nonlinearity of graphene is enhanced tremendously, and, subsequently, low thresholds of optical bistability are achieved in the near-infrared region. The thresholds of optical bistability and the interval between the upper and lower thresholds decrease with the increase in environmental temperature, while the bistable thresholds increase with the addition of the incident wavelength. Furthermore, the critical threshold triggering optical bistability can be modulated by environment temperature and the periodic number of photonic crystals as well. The simulations may be found to be applicable for all temperature-sensitive optical switches or sensors in cryogenic environments. [ABSTRACT FROM AUTHOR]

Optical bistability is theoretically analyzed in a hybrid optomechanical system consisting of an optical cavity including a Kerr medium and an optomechanical cavity coupled by direct tunnel coupling. The dynamics of the system is described by Heisenberg–Langevin equations. It is numerically shown that there is a critical value of the Kerr coefficient to observe the bistability of the intracavity intensity for a given coupling rate, and the changing of the Kerr coefficient will lead to the changing of the critical point to observe the bistability as well. In addition, the first critical value to observe bistability becomes larger with the increasing coupling rate between the two cavities. It is also demonstrated that the pump beam required to realize the bistable behavior in the blue sideband regime is significantly smaller than that in the red sideband regime. And the mean intracavity photon number is relatively larger in the red sideband case than that in the blue sideband case. It is remarkable to observe that the mean intracavity photon numbers in both cavities are much lower than that in ordinary situations. [ABSTRACT FROM AUTHOR]

We theoretically study the optical bistability assisted by multipole polarizations in a semiconductor quantum dot (SQD)/metal nanoparticle (MNP) hybrid molecule. We map out bistability phase diagrams within the parameter subspace spanned by (the pumping intensity Ipu, interparticle distance, d) under dipole and multipole approximations. It is shown that the Ipu-correlated bistable region will be broadened greatly in the strong exciton–plasmon coupling regime, and the corresponding lower (upper) bistable threshold is enlarged significantly due to multipole polarization (N = 10) in comparison to that in the dipole approximation (N = 1). However, under the same conditions, the d-correlated bistable region is shrunk at high pump intensities. Our contribution not only offers a better understanding of exciton–plasmon coupling systems but also expands the application of SQD/MNP hybrid molecules in the field of optical bistable nanodevices. [ABSTRACT FROM AUTHOR]

Efficient heat management and control in optical devices, facilitated by advanced thermo‐optic materials, are critical for many applications such as photovoltaics, thermal emitters, mode‐locked lasers, and optical switches. Here, a range of thermo‐optic properties of 2D graphene oxide (GO) films are investigated by precisely integrating them onto microring resonators (MRRs) with control over the film thicknesses and lengths. The refractive index, extinction coefficient, thermo‐optic coefficient, and thermal conductivity for the GO films with different layer numbers and degrees of reduction, as well as reversible reduction and enhanced optical bistability induced by the photo‐thermal effects, are comprehensively characterized. Experimental results show that the thermo‐optic properties of 2D GO films vary widely with the degree of reduction. In addition, significant anisotropy is observed for the thermo‐optic response, enabling efficient polarization‐sensitive devices. The versatile thermo‐optic response of 2D GO substantially expands the scope of functionalities and devices that can be engineered, making it promising for a diverse range of thermo‐optic applications. [ABSTRACT FROM AUTHOR]

We theoretically investigate optical bistability (OB) and optical multistability (OM) in a three-level cascade-type graphene quantum dot system placed in a Fabry–Perot cavity. The results obtained demonstrate that the OB intensity threshold can be controlled by the intensity and detuning of the driving field. Furthermore, since the three applied fields create a closed-loop system, their relative phase is utilized to manipulate OB and OM. The applied coupling field is assumed to be a vortex beam which provides two additional parameters for controlling OB. Our findings reveal that the OB intensity threshold is sensitive to the orbital angular momentum and azimuthal phase of the coupling vortex beam. [ABSTRACT FROM AUTHOR]

In this paper, we study the nonlinear optical bistability (OB) in a symmetrical multilayer structure. This multilayer structure is constructed by embedding a nonlinear three-dimensional Dirac semimetal (3D DSM) into a Fabry–Perot cavity composed of one-dimensional photonic crystals. The OB phenomenon stems from the third order nonlinear conductivity of 3D DSM. The local field of resonance mode could enhance the nonlinearity and reduce the thresholds of OB. This structure achieves the tunability of OB due to the fact that the transmittance could be modulated by the Fermi energy. It is found that the OB threshold and threshold width could be remarkably reduced by increasing the Fermi energy of the 3D DSM. Besides, we also found that the OB curve depends heavily on the angle of incidence of the incident light, the structural parameters of the Fabry–Perot cavity, and the position of the 3D DSM inside the cavity. After parameter optimization, we obtained OB with a threshold of 10 6   V / m . We believe this simple multilayer structure could provide a reference idea for realizing low-threshold and tunable all-optical switching devices. [ABSTRACT FROM AUTHOR]

The optical response of a two-dimensional supercrystal (monolayer) of quantum emitters with a doublet in the excited state to the action of a continuous external field was theoretically studied, considering the dephasing of the electronic states of the system. The secondary field acting on the V-emitter from other V-emitters of the system forms their nonlinearity and provides internal positive feedback, which leads to bistability and periodic and aperiodic self-oscillations, including chaotic behavior. In the presence of dephasing, the multistability of the optical response is preserved. Phase relaxation leads to a change in the scenario of the system dynamics from chaos to periodic oscillations of the field amplitude, i.e., to a chaos–limit cycle bifurcation and to a decrease in the reflectivity of the monolayer in linear and nonlinear modes. [ABSTRACT FROM AUTHOR]

In this paper, we theoretically investigated the low-threshold and controllable optical bistability (OB) of a graphene-based Otto configuration with a nonlinear three-dimensional Dirac semimetal (3D DSM) as the substrate. The combined effect of the excitation of surface plasmon polaritons (SPPs) in graphene and the very high third-order nonlinear conductivity of the 3D DSM enabled this scheme to achieve a relatively low optical bistability threshold. At the same time, this simple multilayer structure showed the tunability of OB due to the fact that the reflectance could be modulated by regulating the Fermi energy of the 3D DSM. Furthermore, we also found that the OB hysteresis curve was closely related to the relaxation time of the 3D DSM and the thickness of the air layer. We believe that this multilayer configuration could provide a reference idea for devising a bistable device. [ABSTRACT FROM AUTHOR]

In this paper, the effect of a tunable dielectric core on local field enhancement, induced optical bistability, and the optical bistability domain in cylindrical core–shell nanoparticle composites are studied. The local field enhancement factor increases significantly at two resonant frequencies. The results demonstrate that the local field enhancement factor in the cylindrical core–shell nanoparticle increases when the natural attribute of the dielectric function of the dielectric core is varied by adding a dielectric function to it. Furthermore, we demonstrated that the magnitude of the imaginary part of the active dielectric core increases as the onset and offset input intensities increase. This indicates that the optical bistability or threshold width range widens as the imaginary part of the dielectric function of the dielectric core increases, thereby enlarging the threshold domain to improve system activation. [ABSTRACT FROM AUTHOR]

In this study, two ultra-fast all-optical plasmonic switches based on metal–insulator–metal (MIM) plasmonic waveguides side-coupled to the cavity by stubs are proposed. The cavities are filled with a nonlinear Kerr material and the switching occurs due to the self-phase-modulation (SPM) effect. The first structure can achieve an Off–On switching function by adjusting the intensity of the input light or utilizing the optical bistability effect at the 1550 nm and 850 nm telecommunication windows. In the second structure, by adding another nonlinear cavity a two-port switch is designed. The finite-deference time-domain (FDTD) method is used to obtain the simulation results. The ultra-fast switches that are being proposed are equipped with impressive switching mechanisms and have a response time that is measured in picoseconds. The Off–On switch has a response time of 0.25 ps, while the two-port switch has a response time of 1.5 ps. These all-optical switches have the potential to be extremely useful in photonic integrated circuits (PICs). [ABSTRACT FROM AUTHOR]

In this work, we present an analytical method to achieve giant Kerr nonlinearity without absorption in a five-level atomic medium. By using iterative perturbation technique on density matrix equations, we have derived the analytical expressions of nonlinear susceptibility and Kerr nonlinear coefficient in the presence of spontaneously generated coherence (SGC) and relative phase between applied laser fields. It shows that, this five-level atomic medium exhibits multiple electromagnetically induced transparency (EIT) at three different frequencies, at the same time, the Kerr nonlinear coefficient is enhanced around three transparent spectral regions; in each such EIT region appears a pair of positive–negative peaks of Kerr nonlinear coefficient. In particular, these nonlinear peaks are moved to the center of the EIT windows via SGC. This means that the Kerr nonlinear coefficient is enhanced with completely suppressed absorption at different transparency frequencies. Furthermore, the magnitude and the sign of the Kerr nonlinear coefficient are easily controlled according to the SGC strength, the coupling laser intensity, and the relative phase between applied laser fields. Such a giant nonlinear medium can be useful for photonic devices working in the resonant frequency region without absorption. As a typical application, this giant Kerr nonlinear material has been applied to an interferometer for the formation of optical bistability, and showed the appearance of OB at the resonant frequency with significantly reduced threshold intensity and OB width. [ABSTRACT FROM AUTHOR]

We theoretically explore optical bistability/multistability and transmission spectrum in a hybrid optomechanical system consisting of quantum dot molecules in a semiconductor cavity which is in turn coupled to an auxiliary cavity. This auxiliary cavity exhibits both linear and quadratic couplings to a mechanical oscillator. Here, the hybrid optomechanical system is continuously driven by a strong laser from both ends and a weak probe field applied to an auxiliary cavity. The nonlinear nature of the system in the Heisenberg-Langevin equation is taken into consideration and the perturbation method is utilized to deal with problems in the continuous wave regime. The outcome reveals that optical multistability and transmission (absorption and dispersion) spectrum can be deftly manipulated by properly adjusting the parameters. Such an investigation may be useful in designing all-optical switching devices. [ABSTRACT FROM AUTHOR]

The possibility of the longitudinal bistability effect in a system of two parallel lightly-doped silicon wafers divided by a gas-filled gap with controlled width are studied experimentally and theoretically in a thermal chamber of rapid thermal processing set ups. Such a system models a silicon wafer of variable thermal conductivity coefficient between its top layer being in a high-temperature state and its bottom low-temperature layer in a mode of the longitudinal bistability effect in the wafer. It is shown that the longitudinal bistability effect can occur at a relatively small thermal conductivity coefficients of the gap which ranges from 10–2 to 10–1 W/(m K). Such a values of the thermal conductivity coefficient are three orders of magnitude less than thermal conductivity of silicon. As a result, the possibility of the longitudinal bistability in the silicon wafer during its heat treatment in the thermal chamber of rapid thermal processing set-ups is called into question. [ABSTRACT FROM AUTHOR]

Self-organization of radiation in random media is a key to controlling the optical energy flow and constitutes the basis of innovative cavity-free laser designs. Here, we theoretically demonstrate the existence of robust temporal dissipative soliton molecules in a graphene-based active disordered metamaterial. We observe that localized pulses with single and multiple peaks can coexist inside this metamaterial for a wide range of gain parameters, thereby exhibiting optical bistability. We further investigate the stability of such bound states under perturbation by analyzing their interaction force, finding stable tri-soliton molecule states with a periodically oscillating relative phase and a stable bi-soliton molecule. Our results offer a paradigm for mode-locking in active random metamaterials and pave the way for versatile applications such as multilevel encoding in optical communications, future designs of low-cost cavity-free lasers, and optical amplifiers. [ABSTRACT FROM AUTHOR]

The engineering of thermo-optic effects has found broad applications in integrated photonic devices, facilitating efficient light manipulation to achieve various functionalities. Here, we perform both an experimental characterization and a theoretical analysis of these effects in integrated microring resonators made from high-index doped silica, which have had many applications in integrated photonics and nonlinear optics. By fitting the experimental results with theory, we obtain fundamental parameters that characterize their thermo-optic performance, including the thermo-optic coefficient, the efficiency of the optically induced thermo-optic process, and the thermal conductivity. The characteristics of these parameters are compared to those of other materials commonly used for integrated photonic platforms, such as silicon, silicon nitride, and silica. These results offer a comprehensive insight into the thermo-optic properties of doped silica-based devices. Understanding these properties is essential for efficiently controlling and engineering them in many practical applications. [ABSTRACT FROM AUTHOR]

The widespread adaptation of systems relying on optically controlled quantum information will require reliable and efficient multi-channel fiber-to-chip connections that function at cryogenic temperatures. Here we demonstrate low loss (2 dB per channel) connections between a single mode fiber array and tapered silicon waveguides down to 5 K using polymer based photonic wire bonds (PWBs). A method is described for assembling the silicon chip and fiber array such that the PWB connections are robust to temperature cycling and cryostat bakeout. The threshold power handling capability of the PWBs is greater than 4 dBm, sufficient to demonstrate optical bistability in silicon microring resonators coupled to the waveguides at 5 K. [ABSTRACT FROM AUTHOR]

In this paper, we proposed a new model based on the electron tunneling effect in a four-level quantum dot molecule (QDM) for studying the optical bistability (OB) and optical multistability (OM). The QDM interacts with a probe and two coupling and Laguerre–Gaussian (LG) fields. We found that by adjusting the electron tunneling effect and the parametric controlling of LG light, the transition from OB to OM or vice versa is possible. Moreover, due to the simultaneous interaction between coupling and LG lights with the same optical transition adjusting the threshold of OB and OM by orbital angular momentum (OAM) of the LG light becomes achievable. Our results show that by adjusting the simultaneous effect of electron tunneling and OAM state of the vortex light, the favorable OB and OM patterns with adjustable intensity thresholds are achievable. Our proposed model may have potential application in quantum information science based on quantum dot (QD) devices. [ABSTRACT FROM AUTHOR]

Free-space nonreciprocal transmission is a crucial aspect of modern optics devices. The implementation of nonreciprocal optical devices through optical nonlinearity has been demonstrated. However, due to the weak nonlinearity of traditional materials, most self-biased nonreciprocal devices are heavily dependent on the high Q strong resonances. In general, these resonances are frequently polarization sensitive. In this work, we propose ultrathin optical metasurface embedding Kerr nonlinearities to achieve nonreciprocal transmission and optical bistability for free-space propagation based on symmetry-protected bound states in the continuum (BICs). Since the structure of the metasurface retains C4ν symmetry, the symmetry-protected BIC is polarization-independent. It is also shown that the nonreciprocal intensity range could be largely tuned by the structure parameters. The demonstrated devices merge the field of nonreciprocity with ultrathin metasurface technologies making this design an exciting prospect for an optical switch, routing, and isolator with optimal performance.

We investigated optical bistability and its temperature dependence in a composite system composed of an all-superconducting photonic crystal and graphene. The photonic crystal, constructed from two types of superconducting sheets, and which is temperature-sensitive and can greatly localize the electric field, alternately supports a defect mode in a cryogenic environment. Graphene is located at the strongest site in the electric field, so the third-order nonlinearity of graphene is enhanced tremendously, and, subsequently, low thresholds of optical bistability are achieved in the near-infrared region. The thresholds of optical bistability and the interval between the upper and lower thresholds decrease with the increase in environmental temperature, while the bistable thresholds increase with the addition of the incident wavelength. Furthermore, the critical threshold triggering optical bistability can be modulated by environment temperature and the periodic number of photonic crystals as well. The simulations may be found to be applicable for all temperature-sensitive optical switches or sensors in cryogenic environments.

A scheme for modulating Kerr nonlinearity and optical bistability (OB) based on a monolayer graphene nanoribbon nanoresonator (NR) and a metallic nanoshell (MNS) is proposed. The MNS is made of an Au nanoshell and a dielectric core. Here, we not only demonstrate that the spectrum of the Kerr coefficient can switch from a four-peaked structure to a two-peaked structure by increasing the shell thickness of the MNS, but also plot bistability phase diagrams in the system’s parameter subspace, revealing that the bistable effect can be controlled via zero-channel, one-channel or two-channels by only changing the shell thickness in a strong exciton-phonon coupling regime. Additionally, the calculated results also show that the material of the core of MNS plays an essential role in tuning OB when the shell thickness is fixed. The findings pave a new way for developing optical Kerr switches and high-flexible bistable nanodevices.

We present a theoretical study on optical bistability (OB), optical multistability (OM) and tunable all-optical switching in a four-level cascade type atomic system. The density matrix formalism is used to find out the response of the probe laser field. We explore OB and OM under unidirectional optical ring cavity configuration. A comparison between the effects of electromagnetically induced transparency and electromagnetically induced absorption windows on OB is presented. The threshold of OB and the hysteresis width can be tuned effectively by adjusting the applied coherent fields. A transition from OB to OM and vice-versa can be easily achieved by tuning the field parameters and the atomic cooperation parameter. Dynamic control of the probe laser propagating through the medium has been investigated. We also demonstrate conversion of a continuous wave input probe field into output switched pulse. The ON/OFF time of the switched probe pulse can also be controlled by tuning the field parameters. [ABSTRACT FROM AUTHOR]

Tide-forced short-term migration of the grounding line (GL) of Antarctic ice shelves can impact ice dynamics at the ice sheet margins and obscures assessments of long-term GL advance or retreat. However, the magnitude of tidally induced GL migration is poorly known, and the spatial patterns and modes of variability are not well characterised. Here we develop and apply a technique that uses Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) repeat-track laser altimetry to locate the inland limit of tidal ice shelf flexure for each sampled tide, enabling the magnitude and temporal variability of tidal GL migration to be resolved. We demonstrate its application at an ice plain north of Bungenstockrücken, in a region of the southern Ronne Ice Shelf subject to large ocean tides. We observe a 1300 km 2 area of ephemeral grounding over which the GL migrates by up to 15 km between low and high tide and identify four distinct modes of migration: linear, asymmetric, threshold and hysteresis. The short-term movement of the GL dominates any long-term migration signal in this location, and the distribution of GL positions and modes contains information about spatial variability in the ice–bed interface. We discuss the impact of extreme tidal GL migration on ice shelf–ocean–subglacial systems in Antarctica and make recommendations for how GLs should be more precisely defined and documented in future by the community. [ABSTRACT FROM AUTHOR]

The external cavity feedback semiconductor laser shows obvious optical bistability in practice. That is, at the same operating temperature, different temperature tuning directions will lead to different laser mode outputs. This will lead to optical mode hopping and unstable output wavelength of the laser. In this work, we measured this phenomenon and explained it through a theoretical model with thermal synchronization considered. Our measured results show obvious bistability and temperature tuning direction dependence. In order to explain this phenomenon, we considered the physical characteristics of each optoelectronic component in the external cavity, and found that the temperature changes of each component were not synchronized over time. After establishing a model that takes into account the thermal asynchrony phenomenon, we have effectively explained this phenomenon. [ABSTRACT FROM AUTHOR]

The bistability effect caused by radiation absorption in mirrors of a compact high-Q cavity at a wavelength of 1550 nm is studied. The effect leads to a hysteresis of the cavity transmission when scanning the radiation frequency in different directions. The dependence of the effect on the cavity supplied power is studied, and the experimental data are compared with simulation results. The effect under study can be used in the development of optical logical devices. [ABSTRACT FROM AUTHOR]

In this study, we experimentally study the dependence of the intensity of laser radiation incident on and transmitted through a layered InSe crystal. A picosecond YAG:Nd3+ laser with a parametric light generator was used as a light source, making it possible to generate light pulses with a duration of ∼ 30 ps, tunable in frequency within the range of 0.75–1.5 μm. Optical bistability in the region of exciton resonance was detected in an InSe crystal at room-temperature under the picosecond YAG:Nd laser. It is shown that the decrease in absorption in the exciton resonance region is associated with the process of exciton–exciton interaction, shielding of excitons, and the Mott transition. [ABSTRACT FROM AUTHOR]

We theoretically investigate optical bistability and entanglement in a hybrid nonlinear system of two coupled cavities via a single-mode waveguide. The left cavity contains an ensemble of N quantum dots (QDs) and a Kerr medium to enhance the nonlinearity as it causes to observe the bistable behaviour of the system. We study the Kerr medium, QD ensemble, and cavity coupling effect on bistability response shown by mean intracavity photons in the left cavity. In addition, we have shown entanglement between different subsystems and found that entanglement can be generated between the two coupled cavity photons, cavity photons, and QD ensembles. Additionally, we investigate the effect of different parameters on entanglement. Our findings show that Kerr nonlinearity and the hopping parameter between the two cavities can effectively control the optical properties of the proposed hybrid system, which can be used to design efficient optical devices and the entangled optical photons have applications such as quantum information transfer. [ABSTRACT FROM AUTHOR]

We numerically investigate the dynamics of a ring consisting of three unidirectionally coupled Erbium-Doped Fiber Lasers (EDLFs) without external pump modulation. The study focuses on the system behavior as the coupling strength is varied, employing a six-dimensional mathematical model that includes three variables for laser intensities and three variables for population inversions of all lasers. Our primary objective is to understand the system evolution towards chaos from a stable equilibrium in the ring, considering the impact of increasing coupling strength. To analyze the system's behavior, we employ various techniques such as time series analysis, power spectra, Poincaré sections, bifurcation diagrams, and Lyapunov exponents. During the transition to chaos, the system undergoes a Hopf bifurcation and a series of torus bifurcations. An essential aspect of this study is the exploration of a rotating wave propagating along the ring, where the wave nature (periodic, quasiperiodic, or chaotic) depends on the coupling strength. Additionally, we observe the coexistence of periodic and chaotic orbits within a specific range of the coupling strength. However, for very strong coupling, this bistability disappears, resulting in a monostable system with a single limit cycle. This regime exhibits potential for applications that demand short laser pulses with a substantial increase in peak power, reaching nearly 20 times higher levels compared to the continuous mode when the lasers are uncoupled. This discovery holds particular importance for optical communication systems, especially considering the attenuation optical signals experience when transmitted over long distances. [ABSTRACT FROM AUTHOR]

Utilizing the modified transfer matrix method, under transverse electric polarization, asymmetric optical bistability is achieved by designing one-dimensional photonic crystals (PCs) with two Bragg reflector segments containing traditional dielectrics and asymmetric defect multilayers consisting of a magnetized ferrite and nonlinear Kerr dielectric. When the incident wave frequency equals the resonance frequency, owing to the breaking of symmetry in the defect layers and the Voigt magneto-optical effect generating in the magnetized ferrite layers together with the Kerr effect existing in the Kerr dielectric layers, the asymmetric optical modulations are presented as the bistable state in the forward propagation and the multistable state in the backward propagation. Also, the diverse energy localization distributions of the electric field in the proposed PCs from the two incident directions are graphically illustrated. Furthermore, the optical bistable switch-up and switch-down thresholds of the proposed resonator can be tailored flexibly by the external magnetic field, the incident angle, the thicknesses of different dielectrics, and the nonlinear coefficient of Kerr dielectric. This work provides a constructive proposal for the design of light modulators, such as the optical isolator, the optical triode, the all-optical diode, and the sensor. [ABSTRACT FROM AUTHOR]

Owing to an additional thinner planar waveguide with micron scale is attracted to the symmetrical metal cladding waveguide (SMCW) with sub-millimeter scale, the interference interaction between different Q-value guided modes would generate a Fano reflectivity curve. In our double metal-dielectric-metal waveguides (DMDMW) structure, a Kerr nonlinear medium is located in the guiding layer of the SMCW where the excited oscillating wave is enormously enhanced. Numerical calculations show that a minute variation of the incident light intensity will give rise to a change in the dielectric constant of the Kerr nonlinear medium and lead to positive feedback. A bistable reflection can be achieved with a low threshold and a large modulation depth because of the sharpness and the asymmetricity of the Fano reflectivity curve.

Optical bistability and multistability are numerically investigated based on periodic superconducting photonic multilayers with graphene in cryogenic environments. Bandgap edge resonances are sensitive to circumstance temperature and can localize the electric field greatly, which is utilized to enhance the nonlinearity of graphene. Consequently, low threshold optical bistability and double-bistability are realized. Optical multistability subsequently arises by increasing the value of circumstance temperature as well. The thresholds of bistability and multistability lower further by decreasing the chemical potential of graphene or promoting the period number of photonic multilayers. The thresholds can be decreased as low as several hundred MW/cm2. The complex structure has a great potential for the development of two- and multiple-valued all-optical switches in low-temperature condition.

Metastable optically controlled devices (optical flip‐flops) are needed in data storage, signal processing, and displays. Although nonvolatile memory relying on phase transitions in chalcogenide glasses has been widely used for optical data storage, beyond that, weak optical nonlinearities have hindered the development of low‐power bistable devices. This work reports a new type of volatile optical bistability in a hybrid nano‐optomechanical device, comprising a pair of anchored nanowires decorated with plasmonic metamolecules. The nonlinearity and bistability reside in the mechanical properties of the acoustically driven nanowires and are transduced to the optical response by reconfiguring the plasmonic metamolecules. The device can be switched between bistable optical states with microwatts of optical power and its volatile memory can be erased by removing the acoustic signal. The demonstration of hybrid nano‐optomechanical bistability opens new opportunities to develop low‐power optical bistable devices. [ABSTRACT FROM AUTHOR]

In the present paper, we study the optical bistability in a hybrid optomechanical system made of two coupled cavities, which consists of an optical cavity and a mechanical oscillator containing semiconductor quantum dot molecules. By solving the Heisenberg–Langevin equations of motion for the system in the steady state limit, we obtain an expression for the cavity photon number, which indicates the existence of optical bistability phenomenon in the proposed double-cavity optomechanical system. The impact of effectual physical parameters of the system on the bistable behavior is studied and discussed. It is shown that the threshold and the hysteresis loop of the optical bistability curves can be controlled and modulated by varying the relevant key parameters such as the frequency detuning, the coupling strength of cavities, the optical decay rate, and the tunneling strength in the quantum dot molecules. As a consequence, however, by proper adjustment of the coupling strength of the two cavities and the detuning, the domain of the bistable region changed which can be utilized for designing and optimizing sensitive all-optical switching and optical sensors. [ABSTRACT FROM AUTHOR]

We propose a scheme to obtain tunable low-threshold optical bistability of reflected beams in optical Tamm plasmon superlattices (TPS). The low-threshold optical bistability is triggered due to the strong third-order non-linearity of graphene and the local field enhancement in the TPS. Our results show that the optical Tamm plasmon superlattices have the ability to lower the bistable threshold even further than the single optical Tamm state. The results show that the hysteresis behavior and optical bistability threshold can be continuously adjusted by changing the applied voltage and the number of graphene layers (N ≤ 4). In particular, the optical bistability in the TPS is affected by the incident angle. Our results introduce a new possible route for low threshold optical bistability in the THz range and provide a new method in the field of all-optical switching applications. [ABSTRACT FROM AUTHOR]

In this paper, we investigate theoretically the tunable low threshold optical bistability (OB) in the terahertz range based on photonic crystals' Fabry–Perot (FP) cavity with a three-dimensional Dirac semimetal (3D DSM). On the one hand, a 3D DSM with a high nonlinear refractive index coefficient creates conditions for the generation of OB. Additionally, the finite film thickness of 3D DSMs leads to significantly a enhanced interaction volume compared to graphene, which allows easier preparation and has stable properties. On the other hand, the resonance of the FP cavity plays a positive role in promoting the tunable low-threshold OB. It was found that the OB threshold and hysteresis curve can be continuously adjusted by manipulating the Fermi energy and relaxation times of a 3D DSM. Additionally, the bistable curve of the composite structure is also closely related to the angle of incident light. Through parameter optimization, OB with a threshold approaching 105 V/m can be obtained. The photonic crystal's FP cavity with a 3D DSM structure provides a feasible way to achieve low-threshold OB and a building block for future integrated all-optical devices. [ABSTRACT FROM AUTHOR]

Nonlinear and bistable optical systems are a key enabling technology for the next generation optical networks and photonic neural systems with many potential applications in optical logic and information processing. Here, a novel bistable resonator-free all-optical waveguide device based on indium tin oxide as nonlinear epsilon-near-zero material providing a cost-efficient and high-performance binarity photonic platform is proposed. The salient features of the proposed device are compatibility with silicon photonics, enabling sub-picosecond operation speeds with moderate switching power. The device can act as an optical analogue of memristor or thyristor and can become an enabling element of photonic neural networks not requiring OEO conversions. [ABSTRACT FROM AUTHOR]

Exciton–polaritons in optical cavities exhibit strong nonlinearities predominantly because of the third-order Kerr-like interactions mediated by the excitonic component. Under quasi-resonant excitation, depending on the energy of the incident laser, it results in the optical limiting or bistable behavior. The latter phenomenon is manifested by the hysteresis loop observed in the input–output power characteristics, when a cavity is quasi-resonantly driven by a laser field. The direction of the loop is typically counterclockwise when increasing and subsequently decreasing the optical power. In this work, we demonstrate the optical bistability with an inverted hysteresis direction. It is observed in an exfoliated CdTe-based semiconductor microcavity when the frequency of the pumping laser is tuned slightly below the lower polariton mode. This unusual behavior is caused by the interplay of the suppression of strong coupling and the redshift of the lower polariton mode energy when increasing the incident power. We show that under these conditions, the polariton microcavity can be used as an optical limiter. All of the experimental observations, the shape and the direction of the hysteresis and the optical limiting behavior, are fully supported by a theoretical model. [ABSTRACT FROM AUTHOR]

Hydrogen ion autocatalytic reactions, especially in combination with an appropriate negative feedback process, show a wide range of dynamical phenomena, like clock behavior, bistability, oscillations, waves, and stationary patterns. The temporal or spatial variation of pH caused by these reactions is often significant enough to control the actual state (geometry, conformation, reactivity) or drive the mechanical motion of coupled pH‐sensitive physico‐chemical systems. These autonomous operating systems provide nonlinear chemistry's most reliable applications, where the hydrogen ion autocatalytic reactions act as engines. This review briefly summarizes the nonlinear dynamics of these reactions and the different approaches developed to properly couple the pH‐sensitive units (e. g., pH‐sensitive equilibria, gels, molecular machines, colloids). We also emphasize the feedback of the coupled processes on the dynamics of the hydrogen ion autocatalytic reactions since the way of coupling is a critical operational issue. [ABSTRACT FROM AUTHOR]

We theoretically investigate optical bistability/multistability and transmission spectrum in a quadratically coupled optomechanical system consisting of an optical cavity with quantum dot molecules inside it. The optomechanical cavity is driven by a strong pump laser and a weak probe field. We observed that the optical tristability in the presence of quadratic optomechanical coupling transforms into optical bistability in the absence of quadratic optomechanical coupling. We further investigate this hybrid system's absorption and dispersion spectrum by changing the various control parameters like quadratic optomechanical coupling and intensity of strong pump laser field. In addition, we observed the superluminal effect of the transmitted probe field by calculating the group velocity index of light, which is influenced by system parameters. Such results may be useful for designing all-optical switching and novel quantum photonic devices. [ABSTRACT FROM AUTHOR]

We theoretically investigate the optical bistability in superconductor–semiconductor photonic crystals composed of graphene. The photonic crystals are symmetric to the center and arranged alternately by the superconductor (HgBa2Ca2Cu3O8+δ) and semiconductor (GaAs) layers. The system supports a defect mode, and graphene is located at the layer interface where the local electric field is the strongest. Consequently, the optical nonlinearity of graphene has been greatly enhanced, and low-threshold optical bistability can be achieved with an incident wavelength red-detuning to the defect mode. The upper and lower thresholds of bistability increase with the increase in the value of low environmental temperature, while the interval between the upper and lower thresholds decreases. This research has a potential application in temperature-controlled optical switches and temperature-controlled optical memory. [ABSTRACT FROM AUTHOR]

A kind of graphene-based perfect absorber which can generate low-threshold and high-extinction-ratio optical bistability in the near-IR band is proposed and simulated with numerical methods. The interaction between input light and monolayer graphene in the absorber can be greatly enhanced due to the perfect absorption. The large nonlinear coefficient of graphene and the strong light-graphene interaction contribute to the nonlinear response of the structure, leading to relatively low switching thresholds of less than 2.5 MW/cm2 for an absorber with a Q factor lower than 1000. Meanwhile, the extinction ratio of bistable states in the absorber reaches an ultrahigh value of 47.3 dB at 1545.3 nm. Moreover, the influence of changing the structural parameters on the bistable behaviors is discussed in detail, showing that the structure can tolerate structural parametric deviation to some extent. The proposed bistable structure with ultra-compact size, low thresholds, high extinction ratio, and ultrafast response time could be of great applications for fabricating high-performance all-optical-communication devices. [ABSTRACT FROM AUTHOR]

A dual-band tunable filter with a 10.5 nm narrowband based on guided-mode resonance grating is demonstrated. The two filtering working bands around 1200 and 1550 nm can be switched by controlling the TE and TM polarization, respectively. And the Q factor as high as 146.7 at 1550 nm is experimentally realized by optimizing the grating parameters. At TE polarization, an asymmetrical line shape is obtained. In addition, the angle-dependent guided-mode resonance (GMR) effect is well studied in the designed GMR grating filter, in which the tunability and optical bistability based on the thermo-optic effect are first demonstrated. [ABSTRACT FROM AUTHOR]

We consider the dynamics of an ensemble of cold atoms coupled to light through radiation pressure in an optical lattice. We show that the steady-state displacement of the atomic ensemble shows bistable behavior which can be tuned by the position of the cold atoms in the Brillouin zone. Further, we describe a scheme to transfer the quantum state of the light field to the atomic field of two ensembles of cold atoms inside two independent optical cavities. This method leads to quantum entanglement which can be used in implementing quantum communication and computing. An Einstein-Podolsky-Rosen (EPR) state may be achieved with a judicious choice of parameters for our system. [ABSTRACT FROM AUTHOR]

The engineering of thermo-optic effects has found broad applications in integrated photonic devices, facilitating efficient light manipulation to achieve various functionalities. Here, we perform both an experimental characterization and a theoretical analysis of these effects in integrated microring resonators made from high-index doped silica, which have had many applications in integrated photonics and nonlinear optics. By fitting the experimental results with theory, we obtain fundamental parameters that characterize their thermo-optic performance, including the thermo-optic coefficient, the efficiency of the optically induced thermo-optic process, and the thermal conductivity. The characteristics of these parameters are compared to those of other materials commonly used for integrated photonic platforms, such as silicon, silicon nitride, and silica. These results offer a comprehensive insight into the thermo-optic properties of doped silica-based devices. Understanding these properties is essential for efficiently controlling and engineering them in many practical applications.