  Light's orbital angular momentum (OAM) is an unbounded degree of freedom
emerging in helical beams that appears very advantageous technologically. Using
a chiral microlaser, i.e. an integrated device that allows generating an
emission carrying a net OAM, we demonstrate a regime of bistability involving
two modes presenting distinct OAM (L = 0 and L = 2). Furthermore, thanks to an
engineered spin-orbit coupling of light in the device, these modes also exhibit
distinct polarization patterns, i.e. cirular and azimuthal polarizations. Using
a dynamical model of rate euqations, we show that this bistability arises from
polarization-dependent saturation of the gain medium. Such a bistable regime
appears very promising for implementing ultrafast optical switches based on the
OAM of light. As well, it paves the way to the exploration of dynamical
processes involving phase and polarization vortices.
