Few photons probe third-order nonlinear properties of nanomaterials in a plasmonic nanocavity

• Main Authors: Kumari, Anupa, Aghdaee, MohammadReza, Van de Voorde, Mathis, Ojambati, Oluwafemi S
• Format: Journal Article
• Language: English
• Published: 04-11-2024
• Subjects: Physics - Optics
• DOI: 10.48550/arxiv.2411.02315

Quantification of nonlinear optical properties is required for nano-optical
devices, but they are challenging to measure on a nanomaterial. Here, we
harness enhanced optical fields inside a plasmonic nanocavity to mediate
efficient nonlinear interactions with the nanomaterials. We performed
reflection Z-scan technique at intensity levels of kWcm^2, reaching down to two
photons per pulse, in contrast to GWcm^2 in conventional methods. The few
photons are sufficient to extract the nonlinear refractive index and nonlinear
absorption coefficient of different nanomaterials, including perovskite and Au
nano-objects and a molecular monolayer. This work is of great interest for
investigating nonlinear optical interactions on the nanoscale and
characterizing nanomaterials, including fragile biomolecules.