Mechanisms of Thickness-Dependent Nonlinear Optical Processes and Ultrafast Dynamics in NbOCl<sub>2</sub>
NbOCl<sub>2</sub> has garnered interest owing to its second-order nonlinear optical properties, but the influence of thickness on its third-harmonic generation (THG) and excited-state dynamics has not been fully investigated. Here, mechanically exfoliated NbOCl<sub>2</sub> flakes were found to produce THG and second-harmonic generation (SHG), simultaneously, and to show a nonmonotonic dependence on sample thickness. The increase in thickness leads to a decrease in the bandgap. The transient absorption spectrum of NbOCl<sub>2</sub> reveals an enhancement of the long-lived excited-state absorption (ESA) at 2.62 eV and a red-shift of the band-edge absorption (BEA). The ground-state bleaching (GSB) exhibits an accelerated relaxation. Additionally, THG of NbOCl<sub>2</sub> arising from three-photon resonant absorption is competing with SHG, while their optimal excitation band varies with thickness. This study improves our understanding of the mechanisms of the thickness of NbOCl<sub>2</sub> and the development of ultrafast photonics and all-optical switching.
Authors
- Jun He (ORCID: https://orcid.org/0000-0002-1479-285X)
- Zhihui Chen (ORCID: https://orcid.org/0000-0002-2968-4632)
- Si Xiao (ORCID: https://orcid.org/0000-0002-7172-3607)
- Jie Zhang
- Yingwei Wang (ORCID: https://orcid.org/0000-0003-1828-8420)
- Haixia Zhu
- Zhaozhe Chen (ORCID: https://orcid.org/0000-0002-2071-4196)
- Jun Li (ORCID: https://orcid.org/0009-0000-0499-6616)
Institutions
- Central South University (CN)
- NeoPhotonics (United States) (US)
- Nanophoton (Brazil) (BR)
Publication Details
- Journal
- The Journal of Physical Chemistry Letters
- Published
- 2025-09-04
- DOI
- https://doi.org/10.1021/acs.jpclett.5c01968
- Citations
- 1
- Primary Topic
- Advanced Fiber Laser Technologies
- Type
- article
- Field-Weighted Citation Impact
- 1.25
Funders
- Education Department of Hunan Province
- National Natural Science Foundation of China