Creating a broadband diffractive graphene orbital angular momentum metalens by laser nanoprinting

Phys.org  October 11, 2023 Orbital angular momentum (OAM) generators based on metasurfaces can achieve ultracompact designs. However, they generally have limited working bandwidth and require complex designs and multistep time-consuming fabrication processes. Researchers in Australia designed broadband graphene OAM metalenses with flexibly controlled topological charges using the detour phase method and fabricated using ultrafast laser nanoprinting. The experimental results agreed well with the theoretical predictions, which demonstrated the accuracy of the design method. The broadband graphene OAM metalenses have broad applications in miniaturized and integrated photonic devices enabled by OAM beams… read more. Open Access TECHNICAL ARTICLE 

New metalens focuses light with ultra-deep holes

Nanowerk  October 13, 2021 Most metasurfaces use monolith-like nanopillars to focus, shape and control light. The taller the nanopillar more versatile control of each color of light. But very tall pillars tend to fall or cling together. Researchers at Harvard University developed a metasurface with more than 12 million needle-like holes drilled into a 5-micrometer silicon membrane rather than very tall pillars to focus light to a single spot. The diameter of these long, thin holes is only a few hundred nanometers, making the aspect ratio nearly 30:1. The hole size variation bends the light towards the lens focus. Holes […]

Tiny optical elements could one day replace traditional refractive lenses

Eurekalert  March 28, 2019 Metalenses are currently limited by their static and their complex and expensive fabrication and for imaging operations such as zooming and focusing. Most metalenses cannot adjust their focal spots without physical motion as the building blocks of these lenses are made of hard materials that cannot change shape once fabricated. Researchers at Northwestern University built a flat and versatile lens out of an array of cylindrical silver nanoparticles and a layer of polymer patterned into blocks on top of the metal array. By simply controlling the arrangement of the polymer patterns, the nanoparticle array could direct […]