Surface‐polariton propagation for scanning near‐field optical microscopy application

Abstract

Surface plasmon-, phonon- and exciton-polaritons exist on specific materials in specific spectral regions. We assess the properties of such travelling surface-bound electromagnetic waves relevant for scanning near-field optical microscopy applications, i.e. the tightness of surface binding, the attenuation, the phase velocity and the coupling with free-space electromagnetic waves. These quantities can be directly determined by photographic imaging of surface plasmon- and surface phonon-polaritons, in both the visible and mid-infared regions. Focusing of mid-infrared surface plasmons is demonstrated. Surface waveguides to transport and focus photons to the tip of a scanning near-field probe are outlined.

Shape effects in tapered metal rods during adiabatic nanofocusing of plasmons

“…This phenomenon is called nanofocusing and it cannot be achieved in conventional optics using dielectric focusing elements that are subject to the diffraction limit of light ͑which does not allow concentration of light energy into regions that are much smaller than the wavelength of light in the medium͒. 15,18,19 Nanofocusing in metallic nanostructures such as tapered rods and tapered optical fibers with metal coating have been studied and analyzed [20][21][22][23][24][25][26][27][28] along with other numerous structures such as tapered circular paraboloidal, 29 metallic gaps and nanowedges, [30][31][32][33][34][35] tapered metal films, 36 nanoparticle lenses, 37,38 and pyramid tips covered in a metal film. 39 A tapered optical fiber coated in thin metal film with a small nanosized hole at the tip ͑optical probe͒ is a wellknown and important component in the near-field scanning optical microscopy, capable of achieving nanoscale resolution.…”

Coupling of surface waves in highly defined one-dimensional porous silicon photonic crystals for gas sensing applications

“…In the past years, surface plasmon resonance 1 ͑SPR͒ phenomena reached wide popularity in a number of different domains such as nonlinear optics, 2 near-field microscopy/ spectroscopy, 3,4 and gas sensing. 5 This large interest is mainly connected to two important features of surface plasmon polaritons ͑SPPs͒: their strong electromagnetic field enhancement and their sensitivity upon changes of the refractive index at metal/dielectric interfaces.…”

Nanoplasmonics Fundamentals and Surface-Enhanced Raman Scattering as a Physical Phenomenon

“…Note that it was suggested earlier [65] that the propagation of SPPs toward the tip can produce energy concentration. Similarly, the nanofocusing of optical energy due to propagation toward the tip of a plasmonic wedge or a cone has also been predicted [66,67].…”