Amplification of Propagating Spoof Surface Plasmon Polaritons in Ring Resonator-Based Filtering Structure

This article presents the amplification of the propagating spoof surface plasmon polariton (SSPP) modes in the ring resonator-based filtering structure. SSPP-based corrugated ring resonator has been used to design a high-Q dual-band bandpass filter (BPF). Afterward, a subwavelength scale amplifier has been embedded on the output port of the designed BPF to provide loss-compensation as well as amplification at the specified frequency bands of the filtering structure. A microwave laminate with a dielectric constant of 3.38 and a height of 1.52 mm is used to develop the proposed circuit. An 8.2 and 9 - dB gains have been obtained at the two frequency bands, respectively. Good agreement has been achieved between simulated and measured results. The proposed loss compensation and amplification of the SSPP modes in the ring resonator-based structure paves a path to develop active biosensing applications and ultracompact spoof plasmonics-based radio frequency (RF)-to-terahertz (THz) transceiver systems.