A non-Reciprocal Waveguide Using Spoof Plasmon Polariton Coupling to a Magnetized Plasma

We demonstrate non-reciprocal (one-way) waveguiding in a microstrip tailored to support the propagation of spoof plasmon polaritons with a resonance near f = 7 GHz. Time-reversal symmetry is broken by coupling the microstrip fields to a gyrotropic magnetized gaseous plasma column thereby exciting non-reciprocal interfacial plasma-vacuum surface plasmon polaritons. The magnetic bias breaks the symmetry of the magnetoplasmon resonances, resulting in a breaking of the bi-directionality of the wave propagation in the microstrip. A suprising feature is the presence of non-reciprocal response over the entire 2-7 GHz region of the spectrum. This broad response is attributed to the non-uniformity of the plasma, as the wavefield tuning to higher frequencies excites plasmon polaritons that move towards regions of high plasma density closer to the center of the plasma column.