Achromatic super-oscillatory lenses with sub-wavelength focusing

• Published in: Light, science & applications Vol. 6; no. 9; p. e17036
• Main Authors: Yuan, Guang Hui, Rogers, Edward Tf, Zheludev, Nikolay I
• Format: Journal Article
• Language: English
• Published: England Springer Nature B.V 08.09.2017; Nature Publishing Group
• Subjects: Diffraction; Light; Original; Oscillations; Robotics; Silica; Silicon wafers; Wavelength; achromatic; super-resolution; super-oscillation
• ISSN: 2047-7538; 2095-5545; 2047-7538
• DOI: 10.1038/lsa.2017.36

Lenses are crucial to light-enabled technologies. Conventional lenses have been perfected to achieve near-diffraction-limited resolution and minimal chromatic aberrations. However, such lenses are bulky and cannot focus light into a hotspot smaller than a half-wavelength of light. Pupil filters, initially suggested by Toraldo di Francia, can overcome the resolution constraints of conventional lenses but are not intrinsically chromatically corrected. Here we report single-element planar lenses that not only deliver sub-wavelength focusing, thus beating the diffraction limit of conventional refractive lenses, but also focus light of different colors into the same hotspot. Using the principle of super-oscillations, we designed and fabricated a range of binary dielectric and metallic lenses for visible and infrared parts of the spectrum that are manufactured on silicon wafers, silica substrates and optical fiber tips. Such low-cost, compact lenses could be useful in mobile devices, data storage, surveillance, robotics, space applications, imaging, manufacturing with light and spatially resolved nonlinear microscopies.