LAUSR

Abstract A platy isolator for plane waves at microwave frequencies is proposed and investigated theoretically. The isolator is a layered structure which consists of a dielectric layer sandwiched by two yttrium-iron-garnet (YIG) layers with opposite remanences. In this isolator structure, there exists a nonreciprocal transverse resonance within the band gap of the YIG materials. The guiding mode related to the transverse resonance exhibits one-way propagation and simultaneously possesses a dispersion band within the light cone in air. Therefore, this nonreciprocal transverse resonance can be excited in the isolator by plane waves incident from air. By using the transfer matrix method, it is shown that high isolation and efficient transmission can be achieved for the proposed isolator without external magnetic field.