Spin-Manipulated Photonic Skyrmion-Pair for Pico-Metric Displacement Sensing

Photonic spin skyrmions with deep-subwavelength features have aroused considerable interest in recent years. However, the manipulation of spin structure in the skyrmions in a desired manner is still a challenge, while this is crucial for developing the skyrmion-based applications. Here, an approach of optical spin manipulation by utilizing the spin-momentum equation is proposed to investigate the spin texture in a photonic skyrmion-pair. With the benefit of the proposed approach, a unique spin texture with spin angular momentum varying linearly along the line connecting the two skyrmion centers is theoretically designed and experimentally verified. The optimized spin texture is then applied in a displacement-sensing system, which is capable of attaining pico-metric sensitivity. Compared with the conventional polarization and phase schemes, the spin-based manipulation mechanism provides a new pathway for optical modulation, which is of great value in nanophotonics from both fundamental and application.

Automated summary

Photonic spin skyrmions with deep-subwavelength features have attracted significant attention in recent years. However, manipulating the spin structure in a desired manner remains a challenge, which is crucial for developing skyrmion-based applications. In this study, an approach of optical spin manipulation using the spin-momentum equation is proposed to investigate the spin texture in a photonic skyrmion-pair. The optimized spin texture exhibits a unique linear variation of spin angular momentum along the line connecting the two skyrmion centers, and it is experimentally verified. This spin texture is then applied in a displacement-sensing system with pico-metric sensitivity, offering a new pathway for optical modulation in nanophotonics.