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Nitrogen-doped silica-core fibre is discussed in the context of a technological basis for the fabrication of Bragg gratings for sensors with enhanced temperature resistance up to 900 °C. To estimate the applicability of this fibre type for the manufacture of high-temperature Bragg grating sensors, the following features are analysed: technology for fabricating fibre preforms, fibre characteristics and particularities of Bragg gratings written therein. Experimental data on the degradation of the gratings' characteristics resulting from a long-term (up to 4 months) annealing at elevated temperatures are presented and discussed. The practical application of this type of sensor in thermometry is given as an example.

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Ionizing radiation induced degradation of poly (2-methoxy-5-(2'-ethyl-hexyloxy) -1,4-phenylene vinylene) in solution J. Appl. Phys. 110, 073510 (2011); 10.1063/1.3644946 Effects of germanium content on sol-gel GeO 2 /γ -glycidoxypropyltrimethoxysilane hybrid planar waveguides prepared at low temperature J. Vac. Sci. Technol. A 22, 564 (2004); 10.1116/1.1697485 Second-order optical nonlinearity and change in refractive index in silica glasses by a combination of thermal poling and x-ray irradiation [This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to ] IP: 136.165.238.131 On: Mon, 22 Dec 2014 15:20:43 054905-2 Brichard et al. J. Appl. Phys. 103, 054905 ͑2008͒ [This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to ] IP: 136.165.238.131 On: Mon, 22 Dec 2014 15:20:43 054905-3 Brichard et al.

This paper presents a modified design of a high-resolution fiber optic sensor that operates on the surface plasmon resonance effect. The sensor is based on the well-known method of generating surface plasmons with the help of an inscribed tilted fiber Bragg grating that excites the cladding modes. Because the original design solution used a polarizing fiber, it was possible to significantly improve the stability of the sensor readings. The specialized mathematical apparatus was used to determine the surface plasmon resonance spectral position. It was experimentally shown that the limit of detection to the refractive index of such a sensor is 2 × 10−6 refractive index units. The sensor's response to the investigated medium temperature change is presented and analyzed. The high resolution of the sensor in detecting protein molecules was demonstrated. Such sensors open wide perspectives for their application in real high-sensitivity sensor systems as biosensors for immune analysis in medical diagnostics.

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Surface plasmon resonance-based fiber-optic sensors are of increasing interest in modern sensory research, especially for chemical and biomedical applications. Special attention deserves to be given to sensors based on tilted fiber Bragg gratings, due to their unique spectral properties and potentially high sensitivity and resolution. However, the principal task is to determine the plasmon resonance wavelength based on the spectral characteristics of the sensor and, most importantly, to measure changes in environmental parameters with high resolution, while the existing indirect methods are only useable in a narrow spectral range. In this paper, we present a new approach to solving this problem, based on the original method of determining the plasmon resonance spectral position in the automatic mode by precisely calculating the constriction location on the transmission spectrum of the sensor. We also present an experimental comparison of various data processing methods in both a narrow and a wide range of the refractive indexes. Application of our method resulted in achieving a resolution of up to 3 × 10−6 in terms of the refractive index.