Plasmonics enabled atomically thin linearly polarized emitter at room temperature

TL;DR

This study demonstrates that a plasmonic array can actively manipulate and enhance the polarized emission of monolayer WSe2 at room temperature, enabling ultrathin polarized light sources.

Contribution

It introduces a hybrid system where a plasmonic array actively controls the polarization and intensity of WSe2 emission at room temperature, a novel approach for 2D material optoelectronics.

Findings

PL emission can be significantly enhanced at plasmonic resonances.

WSe2 emission gains up to 40% linear polarization.

Active tunability of emission via plasmonic environment is demonstrated.

Abstract

Two-dimensional transition metal di-chalcogenide semiconductors provide unique possibilities to investigate strongly confined excitonic physics and a plasmonic platform integrable to such materials constitutes a hybrid system that can be of interest to enable manipulation of their cumulative optical properties. Here we report tuning of excitonic emission from monolayer WSe2, mechanically exfoliated on top of a periodic two dimensional plasmonic array of elliptical gold (Au) nanodiscs. By exploiting the polarization-dependent nature of plasmonic resonance of the nano plasmonic array (NPA), the photoluminescence (PL) emission from the overlaid monolayer WSe2 could be significantly manipulated. PL is preferentially enhanced at the NPA covered regions of the ake when excited closer to the plasmonic resonant frequencies and previously unpolarized WSe2 PL emission gained ~ 20 up to 40 % degree of linear polarization at room temperature. Obtaining significant spectral overlap between the PL spectrum of WSe2 and the polarization tunable plasmonic resonance of the NPA plays a crucial role in this observation. The results demonstrate active tunability of optical emission from WSe2 by using an otherwise passive plasmonic environment and open the possibility of achieving atomically thin linearly polarized emitters at room temperature. In addition to fundamentally interesting physics of such interactions this can be highly desirable for ultrathin orientation sensitive opto-electronic device related applications.