We investigate the influence of transverse-electric–transverse-magnetic (TE–TM) splitting on the nonlinear response and bistability of resonantly driven spinor exciton-polaritons in a spatially homogeneous microcavity system. Using a coupled exciton–photon mean-field model, we find that TE–TM splitting significantly modifies the bistability threshold, hysteresis width, and spin composition of the steady states. In particular, TE–TM splitting counteracts the spin imbalance imposed by elliptically polarized pumping, leading to nearly equal populations of the two spin components and strongly suppressed degree of circular polarization in the steady state. The pump momentum plays a crucial role through its connection to the curvature of the lower polariton dispersion, resulting in distinct nonlinear regimes with different switching thresholds and dynamical responses. The intermediate branch within the hysteresis loop is unstable but may exhibit slow instability growth rates, giving rise to long-lived transient states. These results clarify how TE–TM splitting reshapes bistability and nonlinear spin dynamics in polariton systems and provide insight into the controlling polariton switching behavior through cavity anisotropy and pump parameters.
We investigate the influence of transverse-electric–transverse-magnetic (TE–TM) splitting on the nonlinear response and bistability of resonantly driven spinor exciton-polaritons in a spatially homogeneous microcavity system. Using a coupled exciton–photon mean-field model, we find that TE–TM splitting significantly modifies the bistability threshold, hysteresis width, and spin composition of the steady states. In particular, TE–TM splitting counteracts the spin imbalance imposed by elliptically polarized pumping, leading to nearly equal populations of the two spin components and strongly suppressed degree of circular polarization in the steady state. The pump momentum plays a crucial role through its connection to the curvature of the lower polariton dispersion, resulting in distinct nonlinear regimes with different switching thresholds and dynamical responses. The intermediate branch within the hysteresis loop is unstable but may exhibit slow instability growth rates, giving rise to long-lived transient states. These results clarify how TE–TM splitting reshapes bistability and nonlinear spin dynamics in polariton systems and provide insight into the controlling polariton switching behavior through cavity anisotropy and pump parameters.
We investigate exciton-polariton condensates with a rotating potential induced by an electric field in a semiconductor microcavity ring. In the absence of transverse-electric-transverse-magnetic (TE-TM) splitting, we find that there is a critical laser pump rate, above which the quantized phase slips appear with hysteresis, and there exist quantized average angular momenta at fixed angular velocities, regardless of the pump rate. When considering the TE-TM splitting, we find that there are a series of hysteresis loops with the same intervals which are modulated by the magnitude of the splitting for a linear polarization laser. Further, multistability occurs at large pump rate, and there arises a phase slip for only one spin with large absolute value of the polarization degree, owing to the competition of the TE-TM splitting and energy induced by rotation. These results can be verified experimentally with current technology, and are useful for future electro-optic devices.
We study the nonlinear dynamics of spinor exciton-polaritons in resonantly pumped microcavities. Using steady-state analysis and computing eigenfrequencies via Bogoliubov-like linearization, we show that multiple Hopf bifurcations beyond conventional bistability occur within specific power regimes and are not associated with stable solutions of the system. Owing to nonlinear excitonic interactions, these transitions occur at different pump powers during forward and backward pump sweeps, leading to pronounced hysteresis between fixed-point and limit-cycle states. In the spinor regime, multiple limit-cycle branches and associated dynamical hysteresis loops emerge due to the interplay of polarization coupling and spin-dependent nonlinearities. We show how the locations of the bifurcation points can be tuned by the pump frequency and other system parameters. Our results identify synchronization as the organizing principle underlying limit-cycle formation, dynamical hysteresis, and bifurcation cascades in driven spinor exciton-polariton microcavities.
We present a theoretical study of spin multistability and hysteresis in resonantly pumped exciton–polaritons within semiconductor microcavities. This multistable behavior arises from the nonlinear, polarization-dependent anisotropy of polariton–polariton interactions. Unlike conventional optical bistability in spinless nonlinear optical systems, the dynamics are governed by spin-selective coupling. We calculate the steady-state polariton density and degree of circular polarization of the intracavity polariton field, demonstrating that for a fixed pump polarization, wave vector, and detuning, the degree of polarization could take on multiple values depending on the pump strength. This spin-sensitive multistability lays the groundwork for multichannel optical switches governed not just by total pump intensity but also by its pump polarization.
We investigate a coherently driven exciton--photon microcavity with Kerr nonlinearity in the ultrastrong-coupling regime. When the lower and upper polariton branches are well separated in energy, the full Hopfield--Rabi--Kerr model reduces to an effective single-mode description of the lower polariton. We analyze the stability of the lower-polariton steady states. We show that the resulting bistability is qualitatively similar to that in the strong-coupling regime. However, in the ultrastrong-coupling regime counter-rotating processes and the diamagnetic A2 term renormalize the polariton spectrum and composition, changing the effective detuning Δ~1 and nonlinearity ULPg-dependency beyond the strong-coupling (RWA) picture. As a result, although the semiclassical bistability criterion keeps its standard Kerr--oscillator form, the turning points and hysteresis window are shifted relative to the strong-coupling prediction.
It is shown that a condensate of microcavity exciton-polaritons exhibits bistability between its two orthogonal linearly polarized components for varying nonresonant excitation power.A non-Hermitian splitting of these components results in two parity-symmetric fixed-point solutions of opposite polarization, making up the hysteresis branches.These solutions correspond to the lowest threshold linearly polarized mode, which dominates at low pump powers, and a cross-polarized mode, which appears due to nonlinear pinning at higher excitation powers.The spin symmetry of the solutions extends the nonresonant bistable operation of polariton condensates to the entire equatorial plane of the Poincaré sphere.The results pave the way towards development of tailored bistable, linearly polarized, coherent sources of light.
Exciton-polariton Bose-Einstein condensates (BECs) are newly emerged quantum systems that are capable of showing macroscopic quantum phenomena with intrinsic open-dissipative nature. The spatial distribution of the polariton density, without any external potential, can be controlled by the geometric shape of the pumping laser, enabling the investigation of polariton dynamics with topologically non-trivial configurations. Meanwhile, exciton-polaritons have spin degrees of freedom inherited from excitons and photons, making it a candidate for the realization of quantum logic gates. In this thesis, we will investigate theoretically the nonlinear dynamics of exciton-polariton BECs involving both polaritons' spatial degrees of freedom and spin degrees of freedom, and interactions between them. This thesis is organised as follows: In Chapter 1, we will present an overall review of exiton-polariton systems and important properties of polariton BECs and then introduce the dynamical equations with various interactions that will serve as the main theoretical tool for subsequent chapters. Several polariton pumping and trapping techniques appearing in later chapters will also be introduced. In Chapter 2, we will investigate the superfluidity properties of a single-component polariton condensate under an incoherent annular pumping configuration. By studying the stability properties of polariton persistent currents, we find that the persistent currents can exhibit dynamical instability and energetic-like instability according to different parameter region. A stability phase diagram will be given and its relation with the Landau's criterion will be discussed. In Chapter 3, we will investigate the spin dynamics of a two-component polariton condensate under a homogeneous pumping configuration. Owing to the Josephson coupling, there exist multiple steady state solutions that allow of controlled spin state switching. A desynchronized region where there exists no stable steady solution is found. In the desynchronized region, a desynchronized state beating periodically over time can exist, which will serve as a building block of spin waves presented in the next chapter. In Chapter 4, by combining results from the previous two chapters we will investigate generally the nonlinear dynamics of polariton condensates under an annular pumping configuration. The spin-orbit interaction provided by the Josephson coupling supports azimuthon states that have simultaneous modulations in both amplitude and phase. The azimuthon states, when viewed in a different polarization basis, form rotating spin waves that can be referred to as the optical ferris wheel. In Chapter 5, results from previous chapters will be extended to micocavities that support the anisotropic TE-TM splitting interaction. Rotating singularities (small-scale vortices) are found as a result. Their properties and experimental observation techniques will be discussed. Chapter 2-5 provide a theoretical framework for the nonlinear dynamics of polariton condensates. They rely mostly on optical trapping techniques and are ready to be tested in experiments. In Chapter 6, polaritons trapped by an engineered periodic mesa potential will be discussed. We will investigate the band structure of polaritons under the influence of the periodic potential together with discussions on the phase-modulated interference pattern which corresponds to the polariton Talbot patterns observed in experiments.