Intrinsic Meron Spin Textures in Generic Focused Fields

TL;DR

This paper discovers and experimentally confirms an intrinsic meron-like spin texture in focused optical fields that is robust against noise and disorder, without requiring wavefront engineering, highlighting its potential for resilient photonic applications.

Contribution

It reveals a naturally occurring, intrinsically robust meron spin texture in focused fields, expanding understanding of topological spin structures in optics beyond engineered configurations.

Findings

Intrinsic meron spin textures exist in focused fields.

These textures are robust against polarization and spatial disorder.

The robustness is due to topological protection from phase vortices.

Abstract

Optical spin textures with nontrivial topology hold promise for structured light and photonic information processing, yet their generation typically relies heavily on externally structured light with care. This raises questions about their universal existence and true robustness. Here, we uncover and experimentally verify a meron-like spin texture that emerges intrinsically in focused fields, without any wavefront engineering. This intrinsic meron spin texture, unlike their externally engineered counterparts, exhibits exceptional robustness against a wide range of inputs, including partially polarized and spatially disordered pupils corrupted by decoherence and depolarization. We attribute its resilience to topological protection from phase vortices in the focal field. Our findings reveal a naturally occurring spin structure that is intrinsic to the focused field with exceptional robustness against noise, which complements the existing externally engineered ones. It offers new ingredients into topological spin textures in optics and enriches their potentials for disorder-resilient photonic applications.