Gain-Associated Nonlinear Phenomenon in Single-Conductor Odd-Mode Plasmonic Metamaterials

Nonlinear phenomena such as second-harmonic generation (SHG) play an important role in both optical and microwave technologies. To achieve high second-harmonic (SH) conversion efficiency and single-conductor system adaptability simultaneously, a gain-associated SHG method based on odd-mode spoof surface plasmon polaritons (SSPPs) is proposed. Field analysis indicates that the odd-mode SSPPs can support internal electric potential difference on the cross sections of single-conductor transmission structures to feed active semiconductor chips, which is hardly achieved by the even modes of single-conductor structures. Measured results demonstrate the realization of SHG with a gain of 4.93 dB at 9 GHz based on the odd-mode SSPPs, accompanied by the third-harmonic suppression and backward SH isolation as a result of the customized passband of odd-mode SSPPs. The ingenious detachable chip carrier can easily be disassembled, replaced and repaired, bringing big convenience and adaptability to practical applications. Moreover, the proposed single-conductor active integration method can be extended to other single-conductor devices, which has great potentials in the flexible systems and wearable devices.