Second-harmonic near-field optical microscopy of periodic nanoholes in metal films

✍ Scribed by J. Beermann; S. I. Bozhevolnyi

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 297 KB
• Volume: 1
• Category: Article
• ISSN: 1612-2011
• DOI: 10.1002/lapl.200410115

✦ Synopsis

Using a second-harmonic (SH) scanning near-field
optical microscope (SNOM) working in transmission with an uncoated
fiber tip, we obtain highly detailed fundamental harmonic (FH) and
SH images of a ∼50-nm-thick gold film deposited on a glass
substrate and containing a ∼830-nm-period array of slightly
elongated holes (diameters in perpendicular directions are
∼170 and 260 nm). The FH and SH images for three excitation
wavelengths (730, 800, and 870 nm) are presented for different
polarization combinations of the FH-incident and FH- and
SH-detected radiations. It is seen that the symmetry of the FH
images is primarily determined by the symmetry of surface plasmon
polaritons (SPPs) excited (at the FH wavelength) at the gold-air
interface, whereas the symmetry of the SH images is mainly
governed by the symmetry of holes. We notice large differences in
the strength of SH signals originating at different (nominally
identical) holes and relate this feature to interference in the
developed multiple scattering of SPPs.