Giant second-harmonic generation in ferroelectric NbOI2

Abdelwahab, Ibrahim; Tilmann, Benjamin; Wu, Yaze; Giovanni, David; Verzhbitskiy, Ivan; Zhu, Menglong; Berte, Rodrigo; Xuan, Fengyuan; Menezes, Leonardo de S.; Eda, Goki; Sum, Tze Chien; Quek, Su Ying; Maier, Stefan A. und Loh, Kian Ping (2022): Giant second-harmonic generation in ferroelectric NbOI2. In: Nature Photonics, Vol. 16, No. 9: pp. 644-650

Abstract

Implementing nonlinear optical components in nanoscale photonic devices is challenged by phase-matching conditions requiring thicknesses in the order of hundreds of wavelengths, and is disadvantaged by the short optical interaction depth of nanometre-scale materials and weak photon-photon interactions. Here we report that ferroelectric NbOI2 nanosheets exhibit giant second-harmonic generation with conversion efficiencies that are orders of magnitude higher than commonly reported nonlinear crystals. The nonlinear response scales with layer thickness and is strain- and electrical-tunable;a record >0.2% absolute SHG conversion efficiency and an effective nonlinear susceptibility chi((2))(eff) in the order of 10(-9) m V-1 are demonstrated at an average pump intensity of 8 kW cm(-2). Due to the interplay between anisotropic polarization and excitonic resonance in NbOI2, the spatial profile of the polarized SHG response can be tuned by the excitation wavelength. Our results represent a new paradigm for ultrathin, efficient nonlinear optical components.

• Item Type: Journal article
• Faculties: Physics
• Subjects: 500 Science > 530 Physics
• ISSN: 1749-4885
• Language: English
• DFG: Gefördert durch die Deutsche Forschungsgemeinschaft (DFG) - 390776260