Advances in Engineering Advances in Engineering features breaking research judged by Advances in Engineering advisory team to be of key importance in the Engineering field. Papers are selected from over 10,000 published each week from most peer reviewed journals.
Journal Reference
Applied Physics A, December 2015, Volume 121,Issue 4, pp 1365-1368.
Shuji Mononobe
Toyo University, 2100 Kujirai, Kawagoe-shi, Saitama-ken, 3508585, Japan
Abstract
A double-tapered probe has widely been used for high-throughput NSOM, which has an infrared cutoff wavelength of around 0.8 μm. Some researchers often need a single-mode fiber probe with a visible wavelength cutoff for polarization-modulation NSOM and related techniques. Improvement in the aspect ratio of the probe is the most important issue to be addressed for apertured NSOM applications. This paper proposes a new NSOM fiber and a double-tapered probe with the protruding clad and single-mode waveguide. The fiber consists of Ge-SiO2 core, SiO2 clad, and F-SiO2 support and has a cutoff wavelength of 0.47 μm. The doping ratio profiles of Cl and F must be carefully controlled while fabricating the fiber preform rod. Furthermore, the double-tapered probe is optimized for the aspect ratio on the basis of geometric consideration. To fabricate the proposed probe, the new single-mode fiber was tapered by immersing it in buffered HF solutions. Owing to the protruding clad, the fabricated probe has an aspect ratio of 0.24. The aspect ratio is 1.8 times as high as the fabricated previous probe.
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