Spin-Wave Self-Imaging: Experimental and Numerical Demonstration of Caustic and Talbot-like Diffraction Patterns

TL;DR

This paper demonstrates experimentally and numerically the self-imaging of spin-waves in a magnetic film, revealing caustic and Talbot-like diffraction patterns influenced by frequency and anisotropy, advancing magnonics research.

Contribution

It introduces the first experimental and numerical analysis of spin-wave self-imaging, highlighting the effects of anisotropic dispersion and caustics on interference patterns in magnonic media.

Findings

Caustics dominate at low frequencies and near the diffraction grating.

Talbot-like patterns emerge at larger distances with high diffraction orders.

The study enhances understanding of spin-wave interference in isotropic and anisotropic media.

Abstract

Extending the scope of the self-imaging phenomenon, traditionally associated with linear optics, to the domain of magnonics, this study presents the experimental demonstration and numerical analysis of spin-wave (SW) self-imaging in an in-plane magnetized yttrium iron garnet film. We explore this phenomenon using a setup in which a plane SW passes through a diffraction grating, and the resulting interference pattern is detected using Brillouin light scattering. We have varied the frequencies of the source dynamic magnetic field to discern the influence of the anisotropic dispersion relation and the caustic effect on the analyzed phenomenon. We found that at low frequencies and diffraction fields, the caustics determine the interference pattern. However, at large distances from the grating, when the waves of high diffraction order and number of slits contribute to the interference pattern, the self-imaging phenomenon and Talbot-like patterns are formed. This methodological approach not only sheds light on the behavior of SW interference under different conditions but also enhances our understanding of the SW self-imaging process in both isotropic and anisotropic media.