Resonant metalens resolves to λ/80

Researchers at the Institut Langevin, ESPCI ParisTech & CNRS have designed and created a novel form of subwavelength-structured lens called a metalens, which breaks the diffraction limit but operates in a way very different from that of a conventional near-field lens.

Jul 1st, 2010

Researchers at the Institut Langevin, ESPCI ParisTech & CNRS (Paris, France) have designed and created a novel form of subwavelength-structured lens called a metalens, which breaks the diffraction limit but operates in a way very different from that of a conventional near-field lens. The experimental prototype, built for use in the microwave region (as are many first attempts at fabricating metamaterial optics), produced a far-field image at a resolution of λ/80 of an object consisting of 16 point sources.

The metalens consists of a 2D array of identical subwavelength-sized resonators (in the prototype, they are copper wires); the object, which is placed in the near field of the metalens, is illuminated with broadband light. The near-field energy captured by the lens decomposes into many different spatial modes, each of which remains in the resonators for a different length of time, with the modes with highest spatial detail remaining the longest. The far-field output is recorded and the image reconstructed using an inversion algorithm. The researchers plan to further increase resolution by adding some disorder to the resonators to enhance dispersion. They believe that metalenses can be created at visible wavelengths using nanoparticles or nanowires as resonators. Contact Geoffroy Lerosey at geoffroy.lerosey@espco.fr.

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