New Methods of Enhancing the Thermal Durability of Silica Optical Fibers.

Karol Wysokiński,Tadeusz Tenderenda,Małgorzata Broczkowska,Mateusz Słowikowski,Tomasz Stańczyk,Anna Ziołowicz,Tomasz Nasiłowski,Katarzyna Gibała

doi:10.3390/ma7106947

Karol Wysokiński, Tadeusz Tenderenda + Show 6 more

Open Access

https://doi.org/10.3390/ma7106947

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Journal: Materials	Publication Date: Oct 13, 2014
Citations: 57	License type: CC BY 4.0

Affiliation: Military University of Technology in Warsaw

Abstract

Microstructured optical fibers can be precisely tailored for many different applications, out of which sensing has been found to be particularly interesting. However, placing silica optical fiber sensors in harsh environments results in their quick destruction as a result of the hydrolysis process. In this paper, the degradation mechanism of bare and metal-coated optical fibers at high temperatures under longitudinal strain has been determined by detailed analysis of the thermal behavior of silica and metals, like copper and nickel. We furthermore propose a novel method of enhancing the lifetime of optical fibers by the deposition of electroless nickel-phosphorous alloy in a low-temperature chemical process. The best results were obtained for a coating comprising an inner layer of copper and outer layer of low phosphorous nickel. Lifetime values obtained during the annealing experiments were extrapolated to other temperatures by a dedicated model elaborated by the authors. The estimated copper-coated optical fiber lifetime under cycled longitudinal strain reached 31 h at 450 °C.

Highlights

Optical fibers have revolutionized the telecommunication industry, due to their remarkable properties, such as, for example, large data transfer rate, possibility of multiplexing many signals in one fiber and immunity to external conditions [1]
Electroless nickel was deposited on approximately 1-m long copper-coated optical fibers according to a procedure consisting of the following steps: degreasing in NaOH, etching in HNO3, activation in PdCl2/HCl solution and electroless plating
We have presented an analysis of the long-term thermal durability of copper-coated silica fibers and a method of enhancing such durability by the deposition of an additional layer of electroless nickel-phosphorous alloy

Summary

Introduction

Optical fibers have revolutionized the telecommunication industry, due to their remarkable properties, such as, for example, large data transfer rate, possibility of multiplexing many signals in one fiber and immunity to external conditions [1]. In the last three decades, optical fibers were widely investigated for applications in the sensing industry. This is mainly because of their compact size, flexibility, possibility of both point and distribution sensing and often low cost [2]. Apart from the physical parameters, the concentration of chemical and biochemical entities can be detected using microstructured optical fibers This includes sensors of pH [9], humidity [10], gases, such as methane [11] or ammonia, and even biochemical sensors, which can detect molecules, like proteins [12] or DNA [13]. The principle of operation of chemical sensors can be based on absorption within a hollow core [11], evanescent field absorption [14], fluorescence [15] or Raman spectroscopy (including surface-enhanced Raman spectroscopy [16])

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Conclusion