Characteristics, Applications, and Properties of Carbon-Dioxide-Laser-Induced Long-Period Fiber Gratings

Long-period fiber gratings (LPFGs) are typically fabricated by exposing photosensitive optical fiber to ultraviolet light. However, LPFGs can be fabricated by a variety of other techniques, including exposure to carbon-dioxide (CO2) laser light. The physical process by which the refractive-index change is induced in an optical fiber during exposure to CO2 laser light gives CO2-laser-induced LPFGs unique properties when compared to more traditional LPFGs fabricated by exposure to UV light. As such, CO2-laser-induced LPFGs respond differently to external perturbations and useful behavior has been observed, including variable attenuation tuning at a constant wavelength and wavelength tuning at constant amplitude with applied flexure. In order to manipulate, harness, and enhance the unique features of CO2-laser-induced LPFGs, it is necessary to understand their physical properties and optical characteristics. The main objectives of the research presented in this thesis are to quantify experimentally the optical performance of CO2-laser-induced LPFGs with respect to flexure, torsion, and variable incident polarization, to characterize grating cross-sectional refractive-index profiles, and to demonstrate applications of CO2-laser-induced LPFGs that exploit their unique properties. As part of the investigation of the effects of asymmetry, the fabrication and basic transmission characteristics of CO2-laser-induced LPFGs were examined. The polarization-dependent transmission characteristics, specifically polarization-dependent loss and polarization mode dispersion, of CO2-laser-induced LPFGs were investigated. The unique behavior of the gratings in response to applied flexure and applied torsion was also explored. Example variable optical attenuator, optical tunable filter, and fiber-to-waveguide coupler devices illustrate the potential advantages of the asymmetric index profile present in CO2-laser-induced LPFGs for certain applications. A new cross-sectional refractive-index profiling technique was presented that enables measurement of profiles containing small and irregular index variations. The profiling technique was used to measure the cross-sectional refractive-index profiles of optical fiber exposed to CO2 laser light. Future areas of research concerning CO2-laser-induced LPFGs were identified and discussed.Ph.D.Committee Chair: Thomas K Gaylord; Committee Member: Ali Adibi; Committee Member: Gee-Kung Chang; Committee Member: John A. Buck; Committee Member: R. Stephen Wei

Refractive-index profiling of azimuthally asymmetric optical fibers by microinterferometric optical phase tomography

© 2005 Optical Society of AmericaThe definitive version of this paper is available at: http://dx.doi.org/10.1364/OL.30.001126DOI: 10.1364/OL.30.001126Accurate nondestructive refractive-index profiling is needed in the modeling, design, and manufacturing of optical fibers and fiber devices. Most profile measurement techniques cannot correctly characterize fibers with small or irregular refractive-index variations over their cross sections. Microinterferometric optical phase tomography (MIOPT) is a technique that allows measurement of fiber refractive-index profiles exhibiting such variations. We present the first demonstration, to our knowledge, of MIOPT. The profile of a polarization-maintaining fiber is measured by MIOPT and shown to be in agreement with (destructive) fiber end-face measurements. MIOPT is also applied to the limiting case of a symmetric single-mode fiber

Polarization Dependence Suppression of Optical Fiber Grating Sensor in a π-Shifted Sagnac Loop Interferometer

In the sensing applications of optical fiber grating, it is necessary to reduce the transmission-type polarization dependence to isolate the sensing parameter. It is experimentally shown that the polarization-dependent spectrum of acousto-optic long-period fiber grating sensors can be suppressed in the transmission port of a π-shifted Sagnac loop interferometer. General expressions for the transmittance and reflectance are derived for transmission-type, reflection-type, and partially reflecting/transmitting-type polarization-dependent optical devices. The compensation of polarization dependence through the counter propagation in the Sagnac loop interferometer is quantitatively measured for a commercial in-line polarizer and an acousto-optic long-period fiber grating sensor

Improving predictive maintenance benefits from online monitoring of spindles: case study in woodworking machine tool

Objective: This article aims to present a case study of the application of an online monitoring system for spindles in a furniture industry, analyzing the benefits to predictive maintenance and business. Methodology/approach: A literature review was carried out followed by a case study Originality/Relevance: Focusing the development of maintenance techniques, especially predictive maintenance and those supported by enabling technologies from Industry 4.0, such as Internet of Things (IoT), it may be possible to carry out online monitoring of spindles with a focus on reducing catastrophic or unplanned events. Main results: The main results are to know the normal behavior of the machine, the possibility of obtaining information in real time, managerial data for sight management, and the possibility of identifying spindle failure before it becomes a catastrophic failure, thus reducing the costs of maintaining the spindles. Theoretical contributions: As a contribution, we discuss the development of the system to digitize the data through the operation available in an outsourced cloud environment. This data can then be returned to the company in the form of dashboards for cash management, developing agility in decision making to facilitate the predictive maintenance in addition to validating the online monitoring system for spindle management in furniture industry processes

Rasmussen chez les Eskimo canadiens.

Bachim M. Rasmussen chez les Eskimo canadiens.. In: Journal de la Société des Américanistes. Tome 16, 1924. pp. 409-410

Exploration archéologique du Yucatan.

Bachim M. Exploration archéologique du Yucatan.. In: Journal de la Société des Américanistes. Tome 16, 1924. pp. 417-418

Nouvelle interprétation de l'inscription du Dayton Rock.

Bachim M. Nouvelle interprétation de l'inscription du Dayton Rock. In: Journal de la Société des Américanistes. Tome 16, 1924. pp. 398-399

Les trésors de l'île de Cocos

Bachim M. Les trésors de l'île de Cocos. In: Journal de la Société des Américanistes. Tome 18, 1926. pp. 359-360