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Coupling transition metal dichalcogenides with dielectric metasurfaces


   Physics / CRANN

   Applications accepted all year round  Funded PhD Project (European/UK Students Only)

About the Project

Coupling transition metal dichalcogenides with dielectric metasurfaces 

Project Overview

The project will investigate the physics and proof of concepts towards new types of photonics devices based on integrating two dimensional dichalcogenides (TMDs) with dielectric metasurfaces. As direct bandgap semiconductors with large exciton binding energy TMDs offer enormous potential for nanoscale photonic devices. They offer low cost and relatively facile fabrication compared with more traditional approaches for nanoscale semiconductor device fabrication. The integration of these materials with photonic structures for controlled light-matter interaction is current hot topic of research.

Strong coupling between excitons and cavity photons has been an active field of research for many decades. Much recent research has concentrated on achieving room temperature strong coupling exploiting the high field enhancement and small mode volume of plasmonic structures1,2. TMDs show strong excitonic effects at room temperature and room temperature strong coupling using a single plasmonic resonators and gap plasmons have been recently demonstrated.  However, the losses associated with the plasmonic nanostructures are quite severe for most applications and is the reason why Rabi splitting though visible in the scattering and absorption spectra is not visible in the photoluminescence spectrum.

Dielectric metasurfaces can potentially overcome some of the drawbacks of plasmonic systems. The Bradley group has published papers on properties of dielectric metasurfaces including high Q-factor quasi-guided modes in TiO2 nanopillar arrays, and wide-angle invisibility Si nanodisk arrays.  Recent theoretical work in our group has shown how coupling dielectric metasurfaces with TMDs provides a platform for investigating strong coupling.

This project will include experimental and numerical studies. It will involve the fabrication and characterization of the metasurfaces, as well as the design and optimization of structures using finite difference time domain simulations. The aims are to demonstrate strong light-matter interaction at room temperature using scattering and PL measurements, and investigation of low energy switching (exciton induced transparency) and low threshold polariton lasing.

Collaborations

This PhD position is part of the PIADS (Photonic Integration and Advanced Data Storage) Centre for Postdoctoral Training. The student will many training opportunities with the other partners, Queen’s University Belfast, University of Glasgow and the Irish Photonics Integration Centre in Tyndall, Cork. More information on the CDT can be found at www.ipic.ie/piads. It is envisaged that the student will spend some time in the lab of Dr. Whelan-Curtin (MTU and IPIC) for the fabrication of the TiO2 metasurfaces. Dr. Fumin Huang from Queen’s University Belfast, with expertise in TMDs, will also collaborate on the project.

Funding Information

The successful applicant will receive a stipend of €18000 per annum as well as full EU student fees for four years. The student will be registered in TCD. The starting date is 1st September 2022. The funding is only available for EU students.

How to apply

Applicants should apply directly to Prof. Louise Bradley at .

Requirements: Students must have achieved, or expect to achieve, a minimum of a II.1 in their undergraduate degree in a Physics, Engineering or Material Science discipline.

Applications should include a full CV and the contact details of 2 academic referees. 


Funding Notes

Funding Information
The successful applicant will receive a stipend of €18000 per annum as well as full EU student fees for four years. The student will be registered in Trinity College Dublin, Ireland. The starting date is 1st September 2022. The funding is only available for EU students.

References

1. Lawless, J. et al. Influence of Gold Nano-Bipyramid Dimensions on Strong Coupling with Excitons of Monolayer MoS2. ACS Appl. Mater. Interfaces 12, 46406–46415 (2020).
2. Kleemann, M. E. et al. Strong-coupling of WSe2 in ultra-compact plasmonic nanocavities at room temperature. Nat. Commun. 8, (2017).
3. Koshelev, K. L., Sychev, S. K., Sadrieva, Z. F., Bogdanov, A. A. & Iorsh, I. V. Strong coupling between excitons in transition metal dichalcogenides and optical bound states in the continuum. Phys. Rev. B 98, 1–6 (2018).
4. Cao, S. et al. Normal-Incidence-Excited Strong Coupling between Excitons and Symmetry-Protected Quasi-Bound States in the Continuum in Silicon Nitride-WS2Heterostructures at Room Temperature. J. Phys. Chem. Lett. 11, 4631–4638 (2020).

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