Plasmonic nanodisk role reversal: From a whispering gallery mode resonator to a reflective mirage

Abstract

Given the pivotal role and extensive applications of optical data routing and processing units in optical information technology, we propose a novel mechanism for switching the optical behavior of plasmonic nanoresonators within photonic integrated circuits. The key concept here is to utilize the Pockels effect not to induce a uniform change in the refractive index profile, but rather to establish an exponential refractive index profile across the nanodisk. This behavior resembles what happens in a mirage phenomenon: the light wave is unable to complete its full path around the nanodisk and is instead reflected back. The proposed plasmonic design bypasses low-transmitted signals and converts them into sharp-band reflected signals in response to a designed bias voltage. Moreover, to the best of our knowledge, our design is the first to achieve the EIT phenomenon and slow light effect using a single resonator, a significant simplification over conventional methods that typically necessitate the use of multiple resonators. This is achieved by creating interference between upward and mirage-induced downward waves, resulting in a transparency window and significant dispersion. © 2024 Elsevier Ltd