Extreme Light-2D matter Interaction at the Atomic Scale

Two-dimensional (2D) materials, such as graphene and transition-metal-dichalcogenides (TMDs), are atomically thin layers, which exhibit extraordinary optical and electrical properties. Since these individual layers are held together by van der Waals (VdW) forces, different 2D materials can be readily placed one on top of each other, enabling the formation of VdW heterostructures with programmable quantum properties [1]. The optical response of 2D materials is especially remarkable [2]. For example, graphene absorbs light from visible to terahertz (THz) frequencies, and supports graphene-plasmons with extremely high momentum in the mid-infrared and THz. TMD monolayers exhibit large refractive indices, and support excitons with very large binding energies, which dominate the optical response of the material. From a technological point of view, the optical properties of 2D materials hold promise for the next generation of optoelectronic devices. In this talk, I will discuss two demonstrations of extreme interaction between light and single atomic layers. In the first part, I will present record-breaking and close-to-unity light absorption by excitonic complexes, which are supported by a TMD semiconductor monolayer in the visible spectrum [3]. In the second part, I will introduce a new and efficient method for exciting extremely high momentum graphene-plasmons, in the mid-infrared spectrum, via magnetic resonators. I will show that this approach also reveals the interaction mechanism of far-field light with near-field graphene-plasmons [4]. These approaches provide new platforms for studying ultra-strong light-matter interaction at the atomic scale, and enable new possibilities for 2D materials-based optoelectronic devices, such as sensors, detectors, and light sources.

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