Near-Field Optical Characterization of Nanocomposite Materials

*We present a near-field optical technique *-hich makes use of the strongly enhanced optical field at a laser-illuminated metal tip. The enhanced field is used to locally excite the sample under investigation by multiphoton absorption. An optical scan image w-ith spatial resolutions dow-n to 20 nm is established by detecting the emitted fluorescence. The principle of the method is described and experimental results are demonstrated for samples of J-aggregates of PIC dye molecules. Ongoing experiments on nanocomposite, Er"-doped oxyfluoride glass-ceramics are discussed.