  Under suitable conditions, some twisted graphene multilayers and
transition-metal dichalcogenides become Chern insulators, exhibiting the
anomalous quantum Hall effect and orbital magnetization due to spontaneous
valley polarization. We study interaction of a Chern insulator with circularly
polarized light. The interaction energy contains an antisymmetric term that
couples to the helicity of incident light. For a two-band Chern insulator, this
term is expressed as an integral involving the Berry curvature of the system.
Taking advantage of this interaction, we propose an experimental protocol for
switching topological memory based on orbital magnetization by circularly
polarized light. Moreover, two laser beams of opposite circular polarization
can nucleate domains of opposite magnetization and thus produce an optically
configurable domain wall carrying topologically protected chiral edge modes.
