Progress in Light-Matter Interplay in 2D Materials from the Near-Infrared to Terahertz Lightwaves towards Monolithic Optoelectronic Devices

Date

May 30, 2025

Time

1:00 PM - 3:00 PM

Speaker

Jian-Bin Xu

Affiliation

Department of Electronic Engineering, CUHK, Hong Kong

Series

TUD nanoSeminar

Language

en

Main Topic

Physik

Other Topics

Physik

Host

Arezoo Dianat

Description

Comprehensive understandings of optoelectronic properties and phenomena at hetero-interfaces and in atomically-thin films play an important role for high-performance device realization. Manipulation of the interplay between matter and photonic structure yields numerous opportunities in fundamental understandings and practical applications. 
 In this presentation, we will present a broad view of 2D in photonics and optoelectronics. Then we will introduce our new understanding of the Fano-type asymmetry deviated from the Rabi-type asymmetry in the exciton-plasmon hybrid system, which is experimentally confirmed with two-dimensional (2D) layered WSe2 coupled to plasmonic lattice. We demonstrate the Fano-type asymmetry in the open plasmon-exciton system both theoretically and experimentally. The Fano-type interference process is found to enhance the lower energy branch (LEB) and reduce the higher energy branch (HEB), rendering the Fano-type asymmetry in the output spectra, even at zero detuning. 
 Secondly, to overcome the large Ohmic loss of plasmonic material, we apply the chemical vapor deposition (CVD) bottom-up method to fabricate the metaphotonic structure based on the bulk transition metal dichalcogenides (TMDCs). More specifically, we realize the magnetic-type surface lattice resonance (M-SLR) in the one-dimensional (1D) MoS2 metaphotonic structure with extremely low material loss. Bright Mie modes and self-coupled anapole-exciton polaritons with unambiguous anti-crossing behavior are also realized in 2D MoS2 metaphotonic structures. However, the aforementioned TMDCs structure does not demonstrate photoluminescence properties. By combining the multilayer (ML) TMDCs to the designed TMDCs metaphotonic structures, we are able to manipulate the polarization and direction of the photoluminescence from the ML TMDCs. 
 Thirdly we leverage the concept of Kerker's effects to demonstrate the dynamic control of scattering directionality in dielectric nanostructures by tuning the exciton-photon coupling. We first provide theoretical evidence for a significant modification of the scattering directionality of a dielectric metastructure engineered by excitonic polaritons. As a proof of concept, we construct self-coupled metasurfaces using bulk MoS2, which exhibit a forward/backward scattering ratio up to 20. Importantly, we achieve tunable directionality by thermally controlling the excitonic coupling to the Mie modes. 
 Fourthly we propose a synergistic effect of chiral near-field and hot carrier injection for actively controlling the valley polarization of WSe2 at room temperature (RT). The degree of valley polarization emission is enhanced from near zero (for pure WSe2) to 20% under non-resonant optical excitation (532 nm) when monolayer WSe2 is integrated with the chiral near field by the plasmonic metasurface. Finally progress in THz wave modulators will be reported.
 References
 [1] X. He, Y. Wang, Z. Peng, J. B. Xu, et al.; On-chip two-dimensional material-based waveguide-integrated photodetectors, Journal of Materials Chemistry C 12, 2279-2316 (2024) Review
 [2] F. H. Shen, Z. Chen, L. Tao, B. L. Sun, X. Xu, J. P. Zheng, and J. B. Xu, Investigation on the Fano-Type Asymmetry in Atomic Semiconductor Coupled to the Plasmonic Lattice, ACS Photonics 8 (12), 3583–3590 (2021).
 [3] F. H. Shen, Z. H. Zhang, Y. Q. Zhou, J. W. Ma, H. J. Chen, S. J. Wang, J. B. Xu, Z. F. Chen, Transition Metal Dichalcogenide Metaphotonics and Self-coupled Polariton Platform Realized by CVD Bottom-up Method, Nature Communications 13, 5597 (2022).
 [4] F. H. Shen, Z. F. Chen, J. B. Xu, et al., Tunable Kerker Scattering in a Self-coupled Polaritonic Metasurface, Laser & Photonics Reviews 18 (1), 202300584; DOI: 10.1002/lpor.202300584 (2024) 
 [5] Z. F. Chen, F. H. Shen, Z. Zhang, K. Wu, Y. Jin, M. Long, S. Wang, J. B. Xu, Synergistic Effect of Chiral Metasurface and Hot Carrier Injection Enables Manipulation of Valley Polarization of WSe2 at Room Temperature, Advanced Physics Research 3 (1), 2300062; https://onlinelibrary.wiley.com/doi/10.1 (2023)

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Last modified: Jun 1, 2025, 7:39:39 AM