Meron Spin Textures in Momentum Space Spawning from Bound States in the Continuum

TL;DR

This paper demonstrates the experimental creation of momentum-space meron spin textures in photonic crystal slabs using bound states in the continuum, revealing their controllability and broad spectral applicability.

Contribution

It introduces a novel method to generate and control momentum-space meron spin textures via BICs in photonic structures, linking real-space and momentum-space topologies.

Findings

Momentum-space merons generated via BICs in photonic crystals.

Polarity-switchable meron configurations controlled by light polarization.

Broad spectral range of operational flexibility.

Abstract

Topological spin textures, such as merons and skyrmions, have shown significance in both fundamental science and practical applications across diverse physical systems. The optical skyrmionic textures in real space have been extensively explored, but which in momentum space are still rarely studied. Here, we report the experimental generation of momentum-space meron spin textures via bound states in the continuum (BICs) in photonic crystal slabs. We show that under circularly polarized illumination, the momentum-space vortex topology of BICs can transform light with meron spin textures in momentum space. These merons exhibit polarity-switchable configurations controlled by incident light polarization. We theoretically and experimentally verify the generation of momentum-space merons and demonstrate their operational flexibility across a broad spectral range. Our results establish a connection between different momentum-space topologies and provide a robust and compact platform for generating topological spin textures.