Mode asymmetry in magneto-plasmonic slot waveguides enabling the design of non-reciprocal devices

The non-reciprocal behavior of integrated plasmonic slot waveguides is driven by the magneto-plasmonic effect, which arises from the interaction between magneto-optical materials and coupled plasmonic modes. This phenomenon provides a strong foundation for the design of advanced integrated non-reciprocal devices. Here, the electromagnetic analysis of magneto-plasmonic slot waveguides is reported. The performance of magneto plasmonic slot waveguides is evaluated in terms of Intensity Ratio (IR0), which quantify the asymmetrization of the propagation modes, and of Propagation Loss (PL). Moreover, a Figure of Merit (FoM), defined as the ratio between IR0 and PL, is proposed as a quality measure to evaluate the efficiency of magneto-plasmonic waveguides, making them suitable for use in non-reciprocal devices. Numerical results demonstrate that an IR0 of 20 dB can be attained in a magneto-plasmonic slot waveguide with propagation loss PL of 0.18 dB/μm, yielding a FoM of 1.2 at the optical wavelength of 1.55 μm.