# Formation, stability, and highly nonlinear optical response of excitons to intense light fields interacting with two-dimensional materials

**Authors:** Eduardo B. Molinero, Bruno Amorim, Mikhail Malakhov, Giovanni Cistaro, Álvaro Jiménez-Galán, Misha Ivanov, Antonio Picón, Pablo San-José, Rui E. F. Silva  
**arXiv:** [2307.16647](https://arxiv.org/abs/2307.16647)  
**Date:** 2023-07-31  
**Summary page:** https://www.summarizepaper.com/en/paper/2307.16647v1/

## Key points

- Excitons play a crucial role in the linear optical response of 2D materials.
- Their significance in the highly nonlinear optical response to intense mid-infrared light has often been overlooked.
- The authors focus on hexagonal boron nitride (hBN) as a prototypical 2D material and demonstrate that excitons play a major role in this highly nonlinear optical process.
- Excitons can persist and become more stable under intense low-frequency fields, challenging previous assumptions.
- A parallelism is established between their results and the physics of Rydberg states using an atomic model, helping understand exciton behavior under intense light fields.
- The authors propose an experimental setup to test the effect of excitons in the nonlinear optical response.
- Considering excitonic effects expands our understanding of these fundamental particles and opens up new possibilities for controlling their properties in optoelectronics and photonics.

## Summary

Excitons, which are bound states of electrons and holes in a material, have long been known to play a crucial role in the linear optical response of two-dimensional (2D) materials. However, their significance in the highly nonlinear optical response to intense mid-infrared light has often been overlooked. In this study, the authors focus on hexagonal boron nitride (hBN) as a prototypical 2D material and theoretically demonstrate that excitons play a major role in this highly nonlinear optical process. Specifically, the authors illustrate the formation and stability of excitons in intense low-frequency fields where the field strengths surpass the Coulomb field binding the electron-hole pair within the exciton. This finding challenges previous assumptions that excitons would dissociate under such intense conditions; instead they show that excitons can persist and even become more stable due to their interaction with intense light fields. To further understand these findings, the authors establish a parallelism between their results and the well-known physics of Rydberg states using an atomic model. This comparison helps elucidate the behavior of excitons under intense light fields and provides insights into their stability. Finally, based on their theoretical findings, the authors propose an experimental setup to test the effect of excitons in the nonlinear optical response. By designing experiments that can probe excitonic effects under intense mid-infrared light, researchers can validate these theoretical predictions and gain a deeper understanding of exciton dynamics in 2D materials. In summary, this study highlights the importance of considering excitonic effects in highly nonlinear optical responses to intense light fields in 2D materials. The theoretical demonstration of exciton formation and stability under such conditions expands our understanding of these fundamental particles and opens up new possibilities for controlling and manipulating their properties for various applications in optoelectronics and photonics.