Graphene-based non-reciprocal spatial isolator

A novel spatial non-reciprocal isolator based on magnetically biased graphene is introduced and analyzed. A brief review of the gyrotropic properties of graphene is provided. The proposed structure is analyzed in terms of an equivalent dyadic transmission line model. A fundamental difference between the proposed structure and the ferrite-based spatial isolators is that the former operates under a small Faraday rotation angle, preventing the need for multiple graphene sheets, whereas the later requires a 45° rotation angle, involving a relatively large and therefore lossy length of ferrite. Moreover, thanks to the strong dependence of isolation on the chemical potential, which may be tuned by a gate voltage, the proposed device may be used as a variable space attenuator.