12:00 〜 12:15
▲ [13a-2C-10] Metallic nanorods array for magnified subwavelength imaging
キーワード：plasmonics,nanolens,super-resolution imaging
Our group proposed a nanostructured lens for su-per-resolution color imaging in the visible range, which is constructed with metallic nanorods, stacked in 3D arrays tapered in a conical shape. The tapered structure is ca-pable of magnifying and transferring near-field image to a long distance. Hence this nanolens realizes the subwave-length super-resolution color imaging in visible range. However, the fabrication of nanolens was limited for scal-ing down components, and increasing accuracy of assem-bling particles in large area, when conventional methods are employed.
In order to taper long chains of metallic nanorods at a certain angle, we experimentally fabricated a 2D nanolens with fan-like shape by using combination of li-thography and self-assembly method, known as the tem-plate-assisted self-assembly (TASA) method. Such con-figuration realizes colored and magnified images. In the fabrication process, chemically synthesized gold nanorods were utilized. The diameter and length of nanorods were ~15 nm and ~50 nm, respectively. These rods were coated with CTAB surfactant to ensure a 10 nm gap between the rods for the resonance control of nanolens. We prepared trenches patterned by FIB lithography on a glass substrate with poly-methyl methacrylate (PMMA) thin layer. The trench width was ~25 nm for precise alignment of Au na-norods. Accurate assembly of gold nanorods was optimized with the different hydrophobicity of PMMA and CTAB coating, aligning nanorods into hydrophilic trenches. After arranging the nanorods into the trenches, we removed the PMMA layer with acetone to clean the surface outside the trenches. Finally, we obtained 2D nanolens after lift-off of the PMMA layer.
Numerical estimation showed a broad peak in the visi-ble range located around the wavelength of 727 nm. The width of this peak (~178 nm) extends in a broad range for multi-color resonance, and optical measurement also proved this phenomenon.
From these results, the combination of lithography and self-assembly has been demonstrated as a potential design to realize metallic nanolens.
In order to taper long chains of metallic nanorods at a certain angle, we experimentally fabricated a 2D nanolens with fan-like shape by using combination of li-thography and self-assembly method, known as the tem-plate-assisted self-assembly (TASA) method. Such con-figuration realizes colored and magnified images. In the fabrication process, chemically synthesized gold nanorods were utilized. The diameter and length of nanorods were ~15 nm and ~50 nm, respectively. These rods were coated with CTAB surfactant to ensure a 10 nm gap between the rods for the resonance control of nanolens. We prepared trenches patterned by FIB lithography on a glass substrate with poly-methyl methacrylate (PMMA) thin layer. The trench width was ~25 nm for precise alignment of Au na-norods. Accurate assembly of gold nanorods was optimized with the different hydrophobicity of PMMA and CTAB coating, aligning nanorods into hydrophilic trenches. After arranging the nanorods into the trenches, we removed the PMMA layer with acetone to clean the surface outside the trenches. Finally, we obtained 2D nanolens after lift-off of the PMMA layer.
Numerical estimation showed a broad peak in the visi-ble range located around the wavelength of 727 nm. The width of this peak (~178 nm) extends in a broad range for multi-color resonance, and optical measurement also proved this phenomenon.
From these results, the combination of lithography and self-assembly has been demonstrated as a potential design to realize metallic nanolens.