Phonon Focusing Effect in an Atomic Level Triangular Structure

Abstract

The rise of artificial microstructures has made it possible to modulate propagation of various kinds of waves, such as light, sound and heat. Among them, the focusing effect is a modulation function of particular interest. We propose an atomic level triangular structure to realize the phonon focusing effect in single-layer graphene. In the positive incident direction, our phonon wave packet simulation results confirm that multiple features related to the phonon focusing effect can be controlled by adjusting the height of the triangular structure. More interestingly, a completed different focusing pattern and an enhanced energy transmission coefficient are found in the reverse incident direction. The detailed mode conversion physics is discussed based on the Fourier transform analysis on the spatial distribution of the phonon wave packet. Our study provides physical insights to achieving phonon focusing effect by designing atomic level microstructures.