C. Durkan et Iv. Shvets, POLARIZATION EFFECTS IN REFLECTION-MODE SCANNING NEAR-FIELD OPTICAL MICROSCOPY, Journal of applied physics, 83(4), 1998, pp. 1837-1843
It is shown that the polarization state of light emitted from an apert
ure-type scanning near-field optical microscopy (SNOM) tip may be sign
ificantly altered on reflection from a metal surface in close proximit
y (5 nm) to the tip, while remaining unchanged at distances of several
microns. Proximity to dielectric surfaces produces no discernible cha
nge. This effect is discussed and explained theoretically. We demonstr
ate that optical image contrast of metal samples may be enhanced by us
ing this effect. The mechanism of the enhancement is based on selectiv
ely detecting the light emitted from the SNOM aperture and filtering o
ut the light emitted through the sidewalls of the probe. It is also sh
own that images of a metal grating pattern on glass show strong polari
zation contrast, which may be understood in terms of simple dipole-ima
ge dipole schemes and transmission-line concepts. (C) 1998 American In
stitute of Physics.