Fractional‐Order Localized Spoof Surface Plasmons for In‐Phase or Out‐of‐Phase Power Division

Abstract

Localized spoof surface plasmons (LSSPs) are extensively used to develop various functional components due to their excellent characteristics of subwavelength confinement and concomitant near‐field enhancement. In this paper, a rat‐race coupler based on fractional‐order LSSPs is proposed to achieve in‐phase or out‐of‐phase power division. It is a four‐port passive component with the advantage of miniaturization. In simulation and experiment, the feasibility of the rat‐race coupler is demonstrated and the existence of the rare fractional‐order LSSPs modes is conformed. More interestingly, a general design method is suggested, based on which arbitrary fractional‐order LSSPs modes can be constructed by skillfully tailoring the electrical lengths between ports. This paper expands the applications of the LSSPs and enriches the topological properties of the LSSPs.

Localized Spoof Surface Plasmon Skyrmions Excited by Guided Waves

“…Localized spoof surface plasmons (LSSPs) have been proposed to mimic the behaviors of localized surface plasmons (LSPs) and have exciting properties of subwavelength confinement DOI: 10.1002/adfm.202305789 and near-field enhancement. [1][2][3][4][5] They are supported by ultrathin textured metallic disks [6] and are excellent candidates for sensors, [7][8][9][10][11] wearable devices, [12][13][14] planar waveguides, [15][16][17] bandpass filters, [18,19] invisibility cloaks, [20][21][22][23][24][25][26][27] antennas, [28][29][30] vortex-beam emitters, [31][32][33][34] isolators, [35] circulators, [36] directional couplers, [37,38] quasi-bound states in the continuum (quasi-BICs) resonators, [39,40] rat-race couplers, [41] logic gates, [42] etc. They are divided into electric LSSPs [3] and magnetic LSSPs.…”