Si. Bozhevolnyi et T. Geisler, NEAR-FIELD NONLINEAR-OPTICAL SPECTROSCOPY OF LANGMUIR-BLODGETT-FILMS, Journal of the Optical Society of America. A, Optics, image science,and vision., 15(8), 1998, pp. 2156-2162
Using an uncoated fiber tip as a light source and a multilayer Langmui
r-Blodgett film of 2-docosylamino-5-nitropyridine as a sample, we obta
in near-field images at the fundamental-harmonic (FH) and second-harmo
nic (SH) wavelengths for different polarizations and wavelengths of th
e pump light. The spatial resolution of similar to 100 nm is achieved
in near-field SH images that are not correlated with either the topogr
aphical or the FH images. It is directly demonstrated that SH generati
on is most concentrated inside submicrometer-sized (800-500 nm) crysta
llike domains, which are oriented differently but predominantly in the
dipping direction and whose SH efficiency is maximum for pump wavelen
gths in the range of 770-800 nm. (C) 1998 Optical Society of America.