Making Weak Interlayer Excitons Absorb: Manipulating the Effective Oscillator Strength via Purcell Engineering of Critical Coupling
Abstract
Interlayer excitons (IXs) in transition metal dichalcogenide bilayers possess unique dipolar properties, providing a path for exploring correlated many-body phases, electrically tunable dipole-dipole interactions, and long-range exciton transport. However, the large electron-hole separation underlying their dipolar character also results in a significantly reduced oscillator strength, limiting their direct optical interaction with light, and thus the direct probing of their dynamics and many-body interactions. Here, we show that by using Purcell engineering of critical coupling, a weak interlayer transition can absorb as strongly as the dominant intralayer transition, despite its much smaller intrinsic oscillator strength. Using this approach, in an open cavity architecture we demonstrate an order of magnitude IX absorption modulation in bilayer and trilayer MoS2, with doubling of the IX to A-exciton interaction strength weight from ~23% to ~53%. Furthermore, we demonstrate that in a tailored closed cavity architecture, the IX enhancement can reach beyond an order of magnitude, from ~5% to ~83% excitonic absorption, enabling IX absorption similar to intralayer excitons. An analytical description of the interaction is obtained via a closed-form transmission-line model which separates the excitonic and photonic contributions to the optical response, revealing how cavity architecture can be designed towards critical coupling. Our findings establish Purcell engineering of critical coupling as a general route to controlling and enhancing weak excitonic transitions.
Related
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BibTeX
@misc{poudyal2026making,
title = {{Making Weak Interlayer Excitons Absorb: Manipulating the Effective Oscillator Strength via Purcell Engineering of Critical Coupling}},
author = {Saroj Poudyal and Anabel Atash Kahlon and Michael Klein and Matan Meshulam and Yonatan Gershuni and Thomas Poirier and James H. Edgar and Mukesh Kumar and Seth Ariel Tongay and Itai Epstein},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.20307},
eprint = {2610.20307},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.20307},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Making Weak Interlayer Excitons Absorb: Manipulating the Effective Oscillator Strength via Purcell Engineering of Critical Coupling
AU - Saroj Poudyal
AU - Anabel Atash Kahlon
AU - Michael Klein
AU - Matan Meshulam
AU - Yonatan Gershuni
AU - Thomas Poirier
AU - James H. Edgar
AU - Mukesh Kumar
AU - Seth Ariel Tongay
AU - Itai Epstein
PY - 2026
DA - 2026/10/14
PB - arXiv
DO - 10.48550/arxiv.2610.20307
UR - https://arxiv.org/abs/2610.20307
AB - Interlayer excitons (IXs) in transition metal dichalcogenide bilayers possess unique dipolar properties, providing a path for exploring correlated many-body phases, electrically tunable dipole-dipole interactions, and long-range exciton transport. However, the large electron-hole separation underlying their dipolar character also results in a significantly reduced oscillator strength, limiting their direct optical interaction with light, and thus the direct probing of their dynamics and many-body interactions. Here, we show that by using Purcell engineering of critical coupling, a weak interlayer transition can absorb as strongly as the dominant intralayer transition, despite its much smaller intrinsic oscillator strength. Using this approach, in an open cavity architecture we demonstrate an order of magnitude IX absorption modulation in bilayer and trilayer MoS2, with doubling of the IX to A-exciton interaction strength weight from ~23% to ~53%. Furthermore, we demonstrate that in a tailored closed cavity architecture, the IX enhancement can reach beyond an order of magnitude, from ~5% to ~83% excitonic absorption, enabling IX absorption similar to intralayer excitons. An analytical description of the interaction is obtained via a closed-form transmission-line model which separates the excitonic and photonic contributions to the optical response, revealing how cavity architecture can be designed towards critical coupling. Our findings establish Purcell engineering of critical coupling as a general route to controlling and enhancing weak excitonic transitions.
ER -