Spectral Tuning in a van der Waals Crystal

Illustration of an effective method for controlling the frequency of confined light at the nanoscale in the form of phonon polaritons. (Source: CIC-nanogune)

Research with nanolight based on phonon polaritons has developed considerably in recent years thanks to the use of sheet-structured nano­materials such as graphene, boron nitride or molybdenum trioxide: the van der Waals materials. Nanolight based on phonon polaritons is very promising because it can live longer than other forms of nanolight, but one of the main drawbacks to the techno­logical appli­cations of this nanolight based on phonon polaritons is the limited frequency ranges charac­teristic of each material, it exists only in narrow frequency region.

But now, an inter­national team led by researchers from the Univer­sity of Oviedo and the Centre for Research in Nanomaterials and Nano­technology (CINN-CSIC) has proposed a novel method that allows to widely extend this range of working fre­quencies of phonon polaritons in van der Waals materials. This consists in the inter­calation of alkaline and alkaline earth atoms, such as sodium, calcium or lithium, in the laminar structure of the van der Waals vanadium penta­oxide material, thus allowing to modify its atomic bonds and conse­quently its optical properties.

Considering that a large variety of ions and ion contents can be inter­calated in layered materials, on-demand spectral response of phonon polari­tons in van der Waals materials can be expected, eventually covering the whole mid-infrared range, something critical for the emerging field of phonon polariton photonics. The finding will allow progress in the development of compact photonic tech­nologies, such as high-sensitivity biological sensors or infor­mation and communi­cation techno­logies at the nanoscale. (Source: CIC-nanogune)

Reference: J. Taboada-Gutiérrez et al.: Broad spectral tuning of ultra-low-loss polaritons in a van der Waals crystal by intercalation, Nat. Mat., online 13 April 2020; DOI: 10.1038/s41563-020-0665-0

Link: Nanomaterials and Nanotechnology Research Center (CINN-CSIC), El Entrego, Spain

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