メタサーフェスを用いて “光学的特異点 “と呼ばれる暗部を生成・制御する新しい方法を2件の研究で報告した。 Two studies report new methods for using metasurfaces to create and control dark areas called “optical singularities”
2023-06-27 ハーバード大学
◆彼らの最新の研究では、メタサーフェスを使用して光だけでなく闇を制御する方法について報告されています。これにより、光学的な闇の領域を設計し、光学トラップや高精度なイメージングなどの画期的な応用が可能となります。この研究は、遠隔センシングや潜在的な検出に重要な影響を与える可能性があります。
＜関連情報＞
- https://seas.harvard.edu/news/2023/06/building-robust-optical-structures-made-darkness
- https://www.nature.com/articles/s41467-023-39072-6
- https://www.science.org/doi/10.1126/sciadv.adh0369
メタサーフェスによる点特異点配列 Point singularity array with metasurfaces
Soon Wei Daniel Lim,Joon-Suh Park,Dmitry Kazakov,Christina M. Spägele,Ahmed H. Dorrah,Maryna L. Meretska & Federico Capasso
Nature Communications Published:05 June 2023
DOI:https://doi.org/10.1038/s41467-023-39072-6
Abstract
Phase singularities are loci of darkness surrounded by monochromatic light in a scalar field, with applications in optical trapping, super-resolution imaging, and structured light-matter interactions. Although 1D singular structures, like optical vortices, are common due to their robust topological properties, uncommon 0D (point) and 2D (sheet) singularities can be generated by wavefront-shaping devices like metasurfaces. With the design flexibility of metasurfaces, we deterministically position ten identical point singularities using a single illumination source. The phasefront is inverse-designed using phase-gradient maximization with an automatically-differentiable propagator and produces tight longitudinal intensity confinement. The array is experimentally realized with a TiO2 metasurface. One possible application is blue-detuned neutral atom trap arrays, for which this field would enforce 3D confinement and a potential depth around 0.22 mK per watt of incident laser power. We show that metasurface-enabled point singularity engineering may significantly simplify and miniaturize the optical architecture for super-resolution microscopes and dark traps.
4次元空間におけるトポロジー的に保護された光偏光特異点 Topologically protected optical polarization singularities in four-dimensional space
Christina M. Spaegele,Michele Tamagnone,Soon Wei Daniel Lim,Marcus Ossiander,Maryna L. Meretska,and Federico Capasso
Science Advances Published:16 Jun 2023
DOI:https://doi.org/10.1126/sciadv.adh0369
Abstract
Optical singularities play a major role in modern optics and are frequently deployed in structured light, super-resolution microscopy, and holography. While phase singularities are uniquely defined as locations of undefined phase, polarization singularities studied thus far are either partial, i.e., bright points of well-defined polarization, or are unstable for small field perturbations. We demonstrate a complete, topologically protected polarization singularity; it is located in the four-dimensional space spanned by the three spatial dimensions and the wavelength and is created in the focus of a cascaded metasurface-lens system. The field Jacobian plays a key role in the design of such higher-dimensional singularities, which can be extended to multidimensional wave phenomena, and pave the way for unconventional applications in topological photonics and precision sensing.
