Article

Analysis of the air holes' geometry influence on longitudinal strain sensitivity of microstructured fiber Bragg gratings

Authors:
  • Karol Stępień DT
  • Polish Center of Photonics and Fibers
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

In this work we present a novel highly Ge doped microstructured fiber design dedicated for fiber Bragg grating (FBG) inscription and longitudinal strain sensing. Three series of the reported fiber differentiated by air-hole diameters were drawn and presented. After numerical analysis of the propagation conditions (with effective refractive index, loss and mode area calculated) in the real structures, the fibers were subjected to femtosecond FBG inscription. We show the resulting typical FBG spectra, as well as measure the longitudinal strain sensitivity of the fabricated samples and its dependence on the microstructure geometry. An increase of approx. 4% in the Bragg wavelength strain sensitivity was noticed for an increase of the large air-hole diameter of approx. 10%.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Furthermore, with the development of microstructured fiber (MSF) technology, it is possible to customize the fiber's properties (e.g. chromatic dispersion [6], [7], sensitivity to pressure [8], strain [9], temperature [10], birefringence [11]), by modifying the fibers internal structural parameters. In addition to a wide variety of optical fibers, sensors that use various measurement methods can also be produced [12], [13]. ...
Conference Paper
In this work we present an innovative method of connecting metal coated optical fibers with metal surfaces. The process is based on electrolytic reaction between copper and allows to obtain a robustand inflexible connection. Furthermore reliability tests of such fiber to metal joints have been performed, with the results of mechanical strength and temperature resistance tests presented. Additionally, as accelerated oxidation of copper at elevated temperatures is a major concern in long term temperature stability of the connection, we propose a method of slowing down the oxidation process with chemical nickel coating. Analysis of the obtained results allows us to predict that the investigated connection may find applications in various industrial optical sensors with special focus on harsh environments.
Conference Paper
In this paper we present the idea and test results of an all-fiber unbalanced Mach-Zehnder interferometer for fiber Bragg grating shift demodulation. The interferometer design allows to monitor Bragg wavelength changes (caused by temperature or strain variations) as changes of intensity on the output detector. Furthermore the construction is cost-effective and based on simple optoelectronic components, which makes the solution attractive for application as a low cost fiber Bragg grating interrogator. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Article
In this study, an innovative method is presented for preparing optical fibers for application in fiber optic sensors operating in harsh environments. It is shown, how to attach a metal-coated fiber electrolytically to a metal sensing element, as well as an electroless method for depositing a nickel protective layer on optical fibers. Additionally, the results of the reliability tests of these methods are presented. It is also shown, that by depositing an additional nickel protective layer, it is possible to slow down the oxidation process of the copper coating. Analysis of the conducted experiments allows us to predict, that the connection method investigated and the method of protecting the fiber are robust and may find application in industrial optical sensors.
Article
Full-text available
We designed, fabricated, and characterized birefringent holey fibers with zero polarimetric sensitivity to temperature. The sensitivity measurements were carried out in a wide spectral range of 0.68–1.55μm in fibers with different hole and pitch values and with birefringence induced by a pair of large holes adjacent to the core. Our results show that zero sensitivity to temperature can be obtained at certain wavelengths for the bare fibers with properly adjusted geometrical parameters. Moreover, the spectral measurements of the sensitivity to temperature are in good agreement with the modeling results for all the investigated fibers.
Article
Full-text available
We designed, manufactured and characterized two birefringent microstructured fibers that feature a 5-fold increase in polarimetric sensitivity to hydrostatic pressure compared to the earlier reported values for microstructured fibers. We demonstrate a good agreement between the finite element simulations and the experimental values for the polarimetric sensitivity to pressure and to temperature. The sensitivity to hydrostatic pressure has a negative sign and exceeds -43 rad/MPa x m at 1.55 microm for both fibers. In combination with the very low sensitivity to temperature, this makes our fibers the candidates of choice for the development of microstructured fiber based hydrostatic pressure measurement systems.
Article
Full-text available
The combination of fiber Bragg grating inscription with femtosecond laser sources and the usage of the Talbot interferometer setup not only gives access to the fabrication of Bragg gratings in new types of materials but also allows, at the same time, to keep the high flexibility of an interferometric setup in choosing the Bragg grating wavelength. Since the spatial and temporal coherence properties of the femtosecond laser source differ strongly from those of conventional laser sources, specific limits and tolerances in the interferometric setup have to be considered. Such limits are investigated on the basis of an analytical ray tracing model. The results are applied to tolerance measurements of fiber Bragg grating reflections recorded with a DUV sub-picosecond laser source at 262 nm. Additionally we demonstrate the wavelength versatility of the two-beam interferometer setup for femtosecond inscription over a 40 nm wavelength band. Inscription experiments in Al/Yb doped silica glasses are demonstrated as a prove for the access to non-photosensitive fibers.
Article
We demonstrate an experimental study of the chromatic dispersion properties for a series of microstructured fibers (MSFs) dedicated for a supercontinuum generation. With white-light interferometry application we analyze experimentally how the small variations of structural parameters, i.e. an air-hole diameter and a lattice constant, influence dispersion characteristics in different groups of MSFs. Our study provides useful information on how to design the fiber which is less sensitive to the fabrication imperfections. Moreover those investigations are the initial step to the development of the customized or tunable supercontinuum light sources based on MSFs with slightly changed structural parameters which can generate light with a different spectrum range, adapted to a proper application.
Article
We report on a photonic crystal fiber with a large mode area designed for compact high power fiber lasers and amplifiers. The fiber suppresses higher order modes when bent around a 10-cm radius and enables single mode operation in small footprint laser and amplifier architectures. We experimentally confirm the peculiar bending properties of this fiber in its passive version, by reporting on the measurement results of fundamental mode loss in bent and straight fibers, and of the influence of the bending plane orientation on this fiber loss.