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Abstract
A tapping-mode scanning near-field optical microscope (SNOM)
system with a bent optical fiber probe has been successfully
developed to study the near-field optics at fiber end-faces.
Topographic and near-field intensity image of fiber end-faces
were obtained simultaneously.A brief and gentle etching
process on fiber end-faces in a saturated solution of ammonium
bifluoride (NH4F˙HF) was able to reveal the structure of
fibers. The topographic features generated by different local
chemistry areclosely related to local doping concentration and
the distribution of refractive index. The correlation
between fiber sturctures and their near- field intensity
profiles of propagating modes can be acquired directly by this
novel method. Micro lens produced by the chemical etch of fiber
endface was studied as well. Variation of propagating near-field
optical intensity distribution shows an increasing effective
index for the existance of micro lens at fiber endface.
Similarly, nano structure fabricated by e-beam
lithography on fiber endface was studied in near- field, and
showed the propagating near-field intensity was modulated by
the existance of this nano structure.
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