Plasmonic amplification and suppression in nanowaveguide coupled to gain-assisted high-quality plasmon resonances

TL;DR

This paper theoretically investigates how gain can be used to control transmission in nanowaveguides coupled with high-quality plasmon resonances, enabling reversible amplification and suppression for plasmonic applications.

Contribution

It introduces a theoretical model demonstrating wide tunability of on-resonance transmission through gain control and waveguide-resonator distance adjustments.

Findings

Transmission varies from -20dB to +20dB with gain changes.

Reversible transition between amplification and suppression is achievable.

Wide transmission variation depends on gain detuning and waveguide-resonator distance.

Abstract

We theoretically study transmission in nanowaveguide coupled to high-quality plasmon resonances for which the metal loss is overcompensated by gain. The on-resonance transmission can vary widely from lower than --20dB to higher than 20dB for a range of gain coefficient. A reversible transition between the high-quality amplification and the suppression can be induced by a quite small change of gain coefficient for a moderately increased distance between the waveguide and the resonator. It is expected that in practice a small change of gain coefficient can be made by flexibly controlling pumping rate or utilizing nonlinear gain. Additionally, based on the frequency-dependant model for gain-transition susceptibility, it is shown that the wide variation of the on-resonance transmission can also be observed for defferent detuning of the gain-transition line-center. Such a widely controllable on-resonance transmission is promising for applications such as well-controlled lumped amplification of surface plasmon-polariton as well as plasmonic switching.