Second-Harmonic Generation of Spoof Surface Plasmon Polaritons Using Nonlinear Plasmonic Metamaterials

TL;DR

This paper demonstrates efficient second-harmonic generation of spoof surface plasmon polaritons at microwave frequencies using nonlinear plasmonic metamaterials integrated on specially designed waveguides, enabling new functionalities in SPP-based circuits.

Contribution

It introduces a novel method for generating second harmonics of spoof SPPs with high efficiency at microwave frequencies using nonlinear active devices on engineered plasmonic waveguides.

Findings

Successful experimental demonstration of second-harmonic SPP generation.

Broadband propagation of spoof SPPs with controllable dispersion.

Potential for SPP frequency multipliers and high-order harmonic generation.

Abstract

The second harmonic generation is one of the most important applications of nonlinear effect, which has attracted great interests in nonlinear optics and microwave in the past decades. To the best of our knowledge, however, generating the second harmonics of surface plasmon polaritons (SPPs) has not been reported. Here, we propose to generate the second harmonics of spoof SPPs with high efficiency at microwave frequencies using subwavelength-scale nonlinear active device integrated on specially designed plasmonic waveguides, which are composed of two ultrathin corrugated metallic strips printed on the top and bottom surfaces of a thin dielectric slab anti-symmetrically. We show that the plasmonic waveguide supports broadband propagations of spoof SPPs with strong subwavelength effect, whose dispersion property can be controlled by changing the geometrical parameters. By loading the nonlinear device made from semiconductors to the intersection of two plasmonic waveguides with different corrugation depths, we experimentally demonstrate the efficient generation of second-harmonic SPPs in broad frequency band. The proposed second-harmonic generator can be directly used as SPP frequency multiplier, and the proposed method can be extended to achieve high-order harmonics and produce SPP mixers, which are essential to SPP integrated circuits and systems.