Photonic Sensors

, Volume 2, Issue 4, pp 331–339 | Cite as

Nanoscopic tip sensors fabricated by gas phase etching of optical glass fibers

  • Jörg Bierlich
  • Jens Kobelke
  • David Brand
  • Konstantin Kirsch
  • Jan Dellith
  • Hartmut Bartelt
Open Access


Silica-based fiber tips are used in a variety of spectroscopic, micro- or nano-scopic optical sensor applications and photonic micro-devices. The miniaturization of optical sensor systems and the technical implementation using optical fibers can provide new sensor designs with improved properties and functionality for new applications. The selective-etching of specifically doped silica fibers is a promising method in order to form complex photonic micro structures at the end or within fibers such as tips and cavities in various shapes useful for the all-fiber sensor and imaging applications. In the present study, we investigated the preparation of geometrically predefined, nanoscaled fiber tips by taking advantage of the dopant concentration profiles of highly doped step-index fibers. For this purpose, a gas phase etching process using hydrofluoric acid (HF) vapor was applied. The shaping of the fiber tips was based on very different etching rates as a result of the doping characteristics of specific optical fibers. Technological studies on the influence of the etching gas atmosphere on the temporal tip shaping and the final geometry were performed using undoped and doped silica fibers. The influence of the doping characteristics was investigated in phosphorus-, germanium-, fluorine- and boron-doped glass fibers. Narrow exposed as well as protected internal fiber tips in various shapes and tip radiuses down to less than 15 nm were achieved and characterized geometrically and topologically. For investigations into surface plasmon resonance effects, the fiber tips were coated with nanometer-sized silver layers by means of vapour deposition and finally subjected to an annealing treatment.


Optical fiber tips nanoprobes gas phase etching doping tip shaping metal coating 


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© The Author(s) 2012

This article is published under license to BioMed Central Ltd. Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.

Authors and Affiliations

  • Jörg Bierlich
    • 1
  • Jens Kobelke
    • 1
  • David Brand
    • 2
  • Konstantin Kirsch
    • 1
  • Jan Dellith
    • 1
  • Hartmut Bartelt
    • 1
  1. 1.IPHT, Institute of Photonic TechnologyJenaGermany
  2. 2.EAH, University of Applied SciencesJenaGermany

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