Tunable spin multistability of cavity polaritons for multichannel optical switching

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.