A magneto-optical isolator (20) for an optical circuit. The isolator includes a substrate, and an optical channel (350) disposed next to the substrate. The optical channel and substrate are configured to transmit optical radiation within the optical channel. The isolator further includes a photonic-crystal rotator (24) formed with the substrate and the optical channel. The rotator has at least one defect (52) and magnetic (M) and non-magnetic (N) materials.