Skyrmions, recognized for their intricate spin configurations, have captivated researchers as topological quasiparticles with vast potential in data storage and information technology. Recently, optical skyrmions—light-based counterparts of these quasiparticles—have emerged as a promising avenue for developing advanced optical systems with unique topological properties.
Existing methods for generating optical skyrmions typically require bulky and complex spatial light modulation setups, limiting their scalability and practical deployment. While approaches using evanescent or magnetic fields have been proposed, these methods are constrained to optical near fields, making detection challenging and long-distance free-space propagation nearly impossible. Achieving subwavelength optical skyrmions without relying on cumbersome systems has been a persistent challenge so far.
Metafibers for Stokes skyrmions
To address this challenge, we developed a flexible metafiber device capable of generating optical skyrmions with customizable topological textures and unprecedented subwavelength polarization features (Fig. 1). Inspired by lab-on-fiber technology, this metafiber platform incorporates metastructures directly onto fiber tips, enabling the creation of structured light fields with precisely tunable topological characteristics. Our study is published in the journal Nature Communications.
Fig 2: The schematic diagram of the skyrmions’ excitation from metafiber. The 3D intensity (I) and vector distribution of the excitation skyrmion are shown after exiting the metafiber. Sz: z-compoment of Stokes vector, PSF: polarization-maintaining single-mode fiber, λ: light wavelength. Inset: (a) The construction principle of skyrmion, composed by zeroth-order Bessel Beam and first-order Bessel Beam under orthogonal left circular polarization (LCP) and right circular polarization (RCP). (b-d) The properties of the excited skyrmion. (b) The elliptical polarization distribution with underneath electric field intensity. (c) Hue-colored Stokes polarization distribution. (d) Hue-lightness (HL)-colored unit Stokes Poincaré sphere. © Tiantian He et al, Optical skyrmions from metafibers with subwavelength features, Nature Communications (2024). DOI: 10.1038/s41467-024-54207-z
As illustrated in Fig. 2, the metafiber design comprises a polarization-maintaining single-mode fiber (PSF), an expansion section, and a metasurface at the fiber tip. By combining orthogonally polarized Bessel beams (zeroth- and first-order) with orbital angular momentum (OAM), the device produces Stokes skyrmions. Adjustments to the metasurface design allow for the creation of various skyrmion types, including Néel-, Bloch-, and anti-skyrmions.
This work can provide a new avenue in optical skyrmion research synergizing meta-photonics and optical fiber technology, offering a versatile and ultracompact device for creating structured light. With its ability to produce high-quality skyrmions with diverse topologies, the metafiber platform opens up exciting possibilities for optical communications, data storage, and beyond.
Summary and outlook
Optical skyrmions are topological light structures with extraordinary characteristics. We introduce metafibers as compact, integrated devices for generating photonic skyrmions with designer topologies and subwavelength polarization control. These advancements offer a practical path to realize structured light for advanced optical technologies.
Future work may explore additional functionalities, such as spin skyrmions and reconfigurable metasurfaces powered by phase-change or 2D materials, further broadening the scope of topologically engineered light fields.
The application of meta-structured fibers highlights the transformative potential of exploring structured light, electromagnetic spin, and sophisticated light field topology, paving the way for further practical applications of optical skyrmions and other applications in optical physics, and nanophotonics.
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More information:
Tiantian He et al, Optical skyrmions from metafibers with subwavelength features, Nature Communications (2024). DOI: 10.1038/s41467-024-54207-z
Yuan Meng, received a PhD in Optical Engineering at Tsinghua University and is currently a postdoctoral associate at Washington University in St Louis.
Citation:
Flexible metafiber device can generate optical skyrmions with designer topological textures and subwavelength features (2024, December 9)
