Polymer dispersed liquid crystal-mediated active plasmonic mode with microsecond response time

Abstract

Active plasmonics combined with liquid crystal (LC) has found many applications in nanophotonics. In this Letter, we propose a fast response active plasmonic device based on the interplay of the plasmonic spectrum and Fabry-Perot (FP) modes. The plasmonic spectrum and FP modes are excited in a layer of gold nanoparticle (NP) islands and an LC microcavity, respectively. The FP mode splits the extinction spectrum of the NP to narrow bands, which are named hybrid modes (HMs). Due to multiple reflections of photons inside the cavity, the extinction coefficient is enhanced compared to a bare NP layer. An external electric field shifts the HM leading to a significant increase in the figure of merit (FoM) related to the activation ability by up to a factor of 45. Additionally, we could reduce the response time of active plasmonics. This decrease in response time is achieved through polymer-dispersed LC (PDLC) in the microcavity. Utilizing a mesogenic monomer in PDLC reduces the response time of the HM into the microsecond range, while the sample remains transparent.