On-chip signal isolation based on mode orthogonality in plasmonic dual-mode transmission line

We propose a spoof surface plasmon polariton (SSPP) dual-mode transmission line (DMTL) formed by mirror serpentine periodic structures (MSPSs), which features the odd- and even-mode dispersion curves overlapping in a wide frequency range. With the mode exciter and mode recognizer in reciprocal form attached to both ends of SSPP DMTL, the two modes can be transmitted at the same time and their orthogonality is validated. An on-chip SSPP DMTL is implemented using the GaAs technology with a compact electrical dimension of 0.125*0.011*0.017λ 3 . The measured efficiencies of odd- and even-mode co-frequency signal transmissions are higher than -1.817dB and -0.89dB, respectively, while the degree of mode isolation is higher than 15 dB. The proposed SSPP DMTL doubles the communication capacity in a fixed frequency band and exhibits great potentials in the composite communication systems.