Research ArticleOPTICS

White nanolight source for optical nanoimaging

See allHide authors and affiliations

Science Advances  03 Jun 2020:
Vol. 6, no. 23, eaba4179
DOI: 10.1126/sciadv.aba4179
  • Fig. 1 Plasmon nanofocusing of white light for full spectral nanoanalysis.

    (A) Schematic of plasmon nanofocusing for white light and spectral bandgap nanoanalysis. (B) Schematic of tapered metallic structure used for simulation. (C) Superposition of waves with different wave vectors.

  • Fig. 2 Broadband property of plasmon nanofocusing evaluated by FDTD simulations.

    (A) Electric field distribution maps in the vicinity of the apex of the tapered silver structure produced by FDTD simulations. Scale bars, 100 nm. The plasmon coupler slit, where white light was illuminated, is not shown, as it is out of the frame. (B) Simulated near-field spectrum detected 6 nm below the apex.

  • Fig. 3 Fabrication of a tapered silver structure on a cantilever tip.

    (A) Schematic of fabrication process of the tapered silver structure on a cantilever tip. (B) Scanning electron microscopy image of the fabricated tapered silver structure on the cantilever tip. The inset shows a side view of the silver layer. Scale bars, 2 μm (inset, 200 nm).

  • Fig. 4 Optical observation of a white nanolight source generated through plasmon nanofocusing.

    (A) Optical image of a tapered silver structure under illumination by supercontinuum laser at its slit. The locations of the boundaries of the tip as well as the slit are indicated by dashed lines. The inset shows a zoomed image of the apex. Incident polarization was normal to the slit as indicated by the arrow. (B and C) Optical images of the same tapered silver structure with supercontinuum laser illumination at different incident polarizations, as indicated by the arrows. (D) Polar graph of the light spot intensity at the apex with respect to the incident polarization; 0° and 90° correspond to parallel and perpendicular polarizations, respectively. (E) Optical images of the tapered silver structure illuminated with a supercontinuum laser, observed through a series of band-pass filters indicated by their central wavelengths. (F) Scattering spectrum of the optical spot at the apex of the tapered silver structure. a.u., arbitrary units. (G) Simulated near-field spectrum calculated at the tip apex. Scale bars, 2 μm (A and E).

  • Fig. 5 Optical nanoimaging of CNTs using the white nanolight source.

    (A) An AFM image of CNT bundles. The structures observed on the left and the right parts of the image are the metallic (m-CNTs) and semiconducting (s-CNTs) CNTs, respectively, as identified during the sample preparation process. Scale bar, 100 nm. (B) Near-field spectra of s-CNTs and m-CNTs, obtained from the locations indicated by the blue and red crosses, respectively, in (A). (C) Near-field spectra obtained pixel by pixel along the dotted line in (A). (D to F) Bandgap images constructed at 620, 680, and 730 nm, respectively. Scale bars, 100 nm.

Supplementary Materials

  • Supplementary Materials

    White nanolight source for optical nanoimaging

    Takayuki Umakoshi, Misaki Tanaka, Yuika Saito, Prabhat Verma

    Download Supplement

    This PDF file includes:

    • Figs. S1 to S6

    Files in this Data Supplement:

Stay Connected to Science Advances

Navigate This Article