Exciton-modulated nonlinear optical frequency conversion in two-dimensional layered nanomaterials

• Grant number: 25/05673-0
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: January 01, 2026
• End date: December 31, 2028
• Field of knowledge: Physical Sciences and Mathematics - Physics
• Principal Investigator: Christiano José Santiago de Matos
• Grantee: Igor Macêdo Gonçalves
• Host Institution: Escola de Engenharia (EE). Universidade Presbiteriana Mackenzie (UPM). Instituto Presbiteriano Mackenzie. São Paulo , SP, Brazil
• Associated research grant: 18/25339-4 - Integrated photonics devices, AP.TEM

Abstract

This project investigates exciton-modulated nonlinear optical frequency conversion in two-dimensional materials, focusing on transition metal dichalcogenides (TMDs). The research aims to understand how excitonic states, both intra- and interlayer, influence second- and third-harmonic generation (SHG and THG) in these materials, considering the strong Coulomb interaction and the absence of inversion centers in certain crystalline phases. A central aspect of this investigation is the nonlinear optics of excited states in TMDs, a topic that remains underexplored in the literature. Recent studies have shown that the presence of excited excitonic states can significantly modulate the nonlinear optical response, including harmonic generation and multiphoton absorption processes. The modulation of these effects through the optical Stark effect enables external control over nonlinear responses, expanding possibilities for applications in advanced photonics. The study will combine experimental and theoretical approaches, utilizing pump-probe spectroscopy and advanced optical and morphological characterization techniques. Comparisons with graphene and TMDs such as MoS¿ will establish reference parameters for the nonlinear optical response of the studied materials. The results aim to advance the fundamental understanding of excited-state nonlinear optics in 2D materials and contribute towards the development of innovative optoelectronic devices, such as optical modulators and sensors based on TMDs. (AU)