<title>Estimation of the influence of accuracy of the fiber Bragg gratings execution on their parameters</title>

Abstract

A new way leading to estimate Fiber Bragg Gratings (FBG) parameters is presented. We describe calculating influence of accuracy of FBG execution on their basic characteristics. In this paper we report and present an FBG element as an optical fiber sensor. An FBG quality characterize two mainly essential parameters. There are Full Width at Half Maximum to stand for FWHM (also presented as z12) and reflection index to stand for R. We examine influence of accuracy of FBG with reference to following quantity: modulation of the refraction index zln and the grating period A. On the basis of well known analytical relationship which describe FWHM and R we have estimated influence of FBG construction on above parameters. After obtain fmal analytical dependences we make suitable graphs to depict all calculations.It has now been more than two decades since the first experiments on the use of optical fibers as sensing elements were conducted. Some of most notable successes in this technology have beed realized in areas including strain and temperature sensing [1]. To date, some types of optical fiber sensors have been commercialized, but it is also true that, among the various techniques that have beed studied, only a limited number of techniques and applications have been commercially successful {2].In comparision with intensometric and interferometric sensors, Fiber Bragg Grating sensors belong to an independent category, which is the most attractive type of fiber optic sensors for embedded sensing [3]. The distinct advantages of FBG sensors, compared with other conventional electric/electronic sensors, can be summarized as fallow: They are lightweight, small and flexible; thus they will not affect the structure integrity of the composite materials and can be integrated with the reinforcing fabrics to form the backbones in structures [4][5][6]. They are based on a single common technology that enables devices to be developed for sensing numerous physical perturbations of mechanical, acoustic, electric, magnetic and thermal nature [7]. A number of sensors can be multiplexed along a single optical fiber using wavelength-, frequency-, time-and polarization-division techniques to form one-, two-or three-dimensional distributed sensing systems [8,9]. They do not provide a conducting path through the structure and do not generate additional heat that could potentially damage the structure [10-14]. They do not require electrical isolation from the structural material and do not generate electromagnetic interference; this could be a crucial advantage in some applications [15,16]. FBG sensors are very well suited for measuring temperature and strain variations. The significant information is directly related to the absolute wavelength change [17]. Quality ofFiber Bragg Gratings characterize two mainly parameters [3]: a) Full Width at Half Maximum FWHM (described also as A2), b) reflection index R.We examined the influence of accuracy of the Fiber Bragg Gratings execution on following quantity: a) refraction index modulation An, b) ...