Fictive temperature in silica-based glasses and its application to optical fiber manufacturing
ABSTRACT This paper will thus give an overview of methods to reduce efficiently the Rayleigh scattering loss via the fictive temperature in silica-based optical fibers. We will first recall what the concept of fictive temperature Tf is and its limitations in section 2. We will see that both Raman and IR spectroscopy can be used to determine Tf (Section 3). Section 4 will thus give some examples of Tf profiles measured in optical fibers manufactured in different conditions. Finally, section 5 will present the main approaches to reduce Rayleigh scattering loss in silica-based fibers via a reduction of Tf.
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ABSTRACT: In the last years, mid-infrared radiation emitted by CO2 lasers has become increasing popular as a tool in the development of long-period fiber gratings. However, although the development and characterization of the resulting sensing devices have progressed quickly, further research is still necessary to consolidate functional models, especially regarding the interaction between laser radiation and the fiber's material. In this paper, a 3D finite element model is presented to simulate the interaction between laser radiation and an optical fiber and to determine the resulting refractive index change. Dependence with temperature of the main parameters of the optical fiber materials (with special focus on the absorption of incident laser radiation) is considered, as well as convection and radiation losses. Thermal and residual stress analyses are made for a standard single mode fiber, and experimental results are presented.Sensors 01/2013; 13(8):10333-47. · 1.95 Impact Factor
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ABSTRACT: The refractive index changes in doped silica are investigated. We observed that the permanent isotropic index change threshold (T1) is not significantly dependent on the doping. We show that strong birefringence (permanent linear birefringence) exists in doped silica but its threshold (T2) exhibits significant dependence on the used dopants. In our conditions, comparing with silica (0.31 μJ/pulse here), for 1.5 at% Ge-doped silica the T2 threshold is smaller (0.14 ± 0.05 μJ/pulse). For a silica doped with 0.3 at% of fluorine, T2 is close to 1.20 ± 0.05 μJ/pulse. An interpretation is given not only about threshold variation but also about RIC for energies beyond. It is based on the overcoming of relaxation time in the volume interaction.Optical Materials Express 07/2011; 1(4):711-723. · 2.62 Impact Factor
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ABSTRACT: The research on the use of fiber sensors based on long-period fiber gratings inscribed by CO2 laser mid-infrared radiation has increased in the last years. In this paper, a set of analytical expressions are used to model the interaction between laser radiation and an optical fiber and to determine the resulting refractive index change. Thermal and residual stress analysis is exemplified for a standard single mode fiber, demonstrating the capability of these models to point out the necessary parameters to achieve proper optical fiber devices based on long period fiber gratings. Experimental results are also presented.Photonic Sensors. 03/2013; 3(1):67-73.