Selective amplification of spoof localized surface plasmons

Here, selective amplification of spoof localized surface plasmons (LSPs) has been demonstrated, where two coupling stubs gathering energies from the spoof LSPs resonator are designed on the back of the corrugated metal-insulator-metal ring resonator. The quadrupole mode is selected and amplified through the coupling stubs and the incorporated amplifier chip, and the measured transmission intensity has been increased from $ - {6.46}\;{\rm dB}$-6.46dB to 10.74 dB by adjusting the bias voltage. The amplification mechanism is fully investigated by using the circuit simulation and the full-wave simulation. The numerical simulations and experimental measurement agree well with each other. The active amplified resonator can be widely used in chemical and biological sensing in microwave frequency.