Researchers Enhance Nonlinear Optical Properties of 2D Material

In a groundbreaking collaboration, engineers from Columbia University and theoretical physicists from the Max Planck Institute for the Structure and Dynamics of Matter have unlocked new potentials in the nonlinear optical properties of a layered 2D material. The discovery hinges on hexagonal boron nitride (hBN), a 2D material with a honeycomb atomic structure that mirrors graphene, and holds quantum properties unique to its thin, exfoliated layers.

Unraveling Quantum Properties in hBN

As outlined in the research published in the esteemed Nature Communications journal, hBN shares an exceptional lightness and room-temperature stability. The boron and nitrogen atoms in this 2D material vibrate with astonishing speed, according to Cecilia Chen, a Ph.D. student at Columbia Engineering. The research specifically targets the optical phonon mode of hBN, which vibrates at 41 THz. This vibration equates to a 7.3 μm wavelength in the mid-infrared region of the electromagnetic spectrum.

Tuning in to Optical Frequencies

By finely adjusting their laser system to match the 7.3 μm frequency, the collaborative team initiated new optical frequencies through a phonon-mediated nonlinear optical process, recognized as four-wave mixing. The result was a spectacular more than thirtyfold increase in third-harmonic generation, a marked improvement compared to results without phonon excitation.

Validating Theoretical Work

The experimental findings were backed by the theoretical work conducted by Professor Angel Rubio's Max Planck group. The Columbia-based team, buoyed by these successful outcomes, intends to delve deeper into how light can further manipulate hBN and similar materials in future studies.