title: Three-dimensional all-dielectric metamaterial solid immersion lens for subwavelength imaging at visible frequencies.
abstract: Although all-dielectric metamaterials offer a low-loss alternative to current metal-based metamaterials to manipulate light at the nanoscale and may have important applications, very few have been reported to date owing to the current nanofabrication technologies. We develop a new "nano-solid-fluid assembly" method using 15-nm TiO2 nanoparticles as building blocks to fabricate the first three-dimensional (3D) all-dielectric metamaterial at visible frequencies. Because of its optical transparency, high refractive index, and deep-subwavelength structures, this 3D all-dielectric metamaterial-based solid immersion lens (mSIL) can produce a sharp image with a super-resolution of at least 45 nm under a white-light optical microscope, significantly exceeding the classical diffraction limit and previous near-field imaging techniques. Theoretical analysis reveals that electric field enhancement can be formed between contacting TiO2 nanoparticles, which causes effective confinement and propagation of visible light at the deep-subwavelength scale. This endows the mSIL with unusual abilities to illuminate object surfaces with large-area nanoscale near-field evanescent spots and to collect and convert the evanescent information into propagating waves. Our all-dielectric metamaterial design strategy demonstrates the potential to develop low-loss nanophotonic devices at visible frequencies.
authors.affiliation: Department of Materials Science and State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200433, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Fan
authors.affiliation: School of Electronic Engineering, Bangor University, Bangor LL57 1UT, UK.
authors.forename: Bing
authors.initials: B
authors.lastname: Yan
authors.affiliation: School of Electronic Engineering, Bangor University, Bangor LL57 1UT, UK.
authors.forename: Zengbo
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Materials Science and State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200433, China.
authors.forename: Limin
authors.initials: L
authors.lastname: Wu
mesh_terms: D055590:Electromagnetic Phenomena; D049329:Nanostructures / Q000737:chemistry*; D061848:Optical Imaging; D014025:Titanium / Q000737:chemistry
chemical_list: C009495:titanium dioxide; D014025:Titanium
keywords: All-dielectric metamaterials; self-assembly, solid immersion lens; super-resolution imaging; titanium dioxide