Manipulation of Circular Polarization States of 2-D TMDCs Emission with Plasmonic Chiral Metamolecules

Abstract

Manipulating circularly polarized (CP) light is critical to the applications include display, quantum communication and bio-sensing. Besides, the compact, CP light emitting devices would more efficiently control CP state of light and benefit to be integrated on chips. In this works, we combined the promising atomic-thin transition metal dichalcogenide (TMDC) material, tungsten diselenide (WSe2), with nanorod based plasmonic chiral metamolecules to demonstrate an ultrathin, CP state controllable light source. The photoluminescence of WSe2 exhibit intrinsic optical chirality due to selective CP state absorption in the band structure K-valleys. And the localized surface plasmon resonances (LSPR) of chiral metamolecules induced strong local confinement of optical mode when integrated with low-dimensional materials. We investigate the intrinsic chiral emission of WSe2 coupled to the LSPR in the chiral metamolecules to generate a wide range of controllable emission circular dichroism (CD) with maxima 400% CD enhancement than bare WSe2. Furthermore, both enhanced and reversed CD have been achieved. The integration of novel gain material and plasmonic structures both low-dimensional lead these compact light sources suitable for practical applications such as chip scale sensors and optical information processing.