Giant and Tunable Optical Nonlinearity in Single‐Crystalline 2D Perovskites due to Excitonic and Plasma Effects. Issue 29 (3rd June 2019)

• Record Type: Journal Article
• Authors: Abdelwahab, Ibrahim; Dichtl, Paul; Grinblat, Gustavo; Leng, Kai; Chi, Xiao; Park, In‐Hyeok; Nielsen, Michael P.; Oulton, Rupert F.; Loh, Kian Ping; Maier, Stefan A.
• Is Part Of: Advanced materials. Volume 31:Issue 29(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-06-03
• Subjects: 2D Ruddlesden–Popper perovskites -- excitonic resonance -- Mott transition -- third‐order optical nonlinearity -- Z‐scan; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.201902685
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Materials with large optical nonlinearity, especially in the visible spectral region, are in great demand for applications in all‐optical information processing and quantum optics. 2D hybrid Ruddlesden−Popper‐type halide perovskites (RPPs) with tunable ultraviolet‐to‐visible direct bandgaps exhibit large nonlinear optical responses due to the strong excitonic effects present in their multiple quantum wells. Using a microscopic Z‐scan setup with femtosecond laser pulses tunable across the visible spectrum, it is demonstrated that single‐crystalline lead halide RPP nanosheets possess unprecedentedly large nonlinear refraction and absorption coefficients near excitonic resonances. A room‐temperature insulator (exciton)–metal (plasma) Mott transition is found to occur near the exciton resonance of the thinnest qunatum‐well RPPs, boosting the nonlinear response. Owing to the rapidly changing refractive index near resonance, a single RPP crystal can exhibit different nonlinear functionalities across the excitation spectrum. The results suggest that RPPs are efficient nonlinear materials in the visible waveband, indicating their potential use in integrated nonlinear photonic applications such as optical modulation and switching. Abstract : Large excitonic optical nonlinearity in single‐crystalline 2D Ruddlesden–Popper perovskite (RPP) nanosheets characterized by a microscopic Z‐scan setup is reported. A room‐temperature excitonic Mott transition occurs near the exciton resonance of the thinnest quantum‐well RPPs, boosting the nonlinear response. The magnitude and sign of the nonlinear coefficients vary strongly with the excitation wavelength offering various nonlinear functionalities in the visible waveband.