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

Hsiang-Ting Lin^1,2*, Chiao-Yun Chang¹, Pi-Ju Cheng¹, Ming-Yang Li^1,3, Chia-Chin Cheng³, Shu-Wei Chang^1,2, Lain-Jong Li³, Chih-Wei Chu¹, Pei-Kuen Wei¹, Min-Hsiung Shih^1,2,4

¹Research Center for Applied Sciences (RCAS), Academia Sinica, Taipei, Taiwan
²Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University (NCTU), Hsinchu, Taiwan
³Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
⁴Department of Photonics, National Sun Yat-sen University (NSYSU), Kaohsiung, Taiwan

* Presenter:Hsiang-Ting Lin, email:linst8168@gmail.com

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.

Keywords: two-dimensional materials, transition metal dichalcogenides (TMDCs), tungsten diselenide (WSe₂), surface plasmon, circular dichroism