594 research outputs found
Optical networking equipment manufacturing
Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science; in conjunction with the Leaders for Manufacturing Program at MIT, 2001.Includes bibliographical references (leaf 70).Celestica, a global contract manufacturer specializing in printed circuit board assembly and computer assembly, has recently begun manufacturing equipment for the optical networking equipment (ONE) industry. The expansion to include ONE manufacturing requires the development of new skills in handling optical fiber and components, a new supply chain strategy, and a new approach to manufacturing systems control. Celestica is developing a set of standards for ONE manufacturing that will support the rapid development of the new skills required for this industry. This work outlines the standards and explores the specific issues related to manufacturing with optical fiber, including the mechanical reliability and optical performance of various types of optical fibers. An overview of the telecommunications industry is provided, including an analysis of its supply chain structure. Observations are made on trends in the industry and the ways that these trends have affected Celestica in the past, and could impact Celestica in the future. Finally, Celestica's current approach to manufacturing systems control is evaluated, and suggestions are made for improving systems control and project management when manufacturing for such a rapidly evolving industry.by Jason Holman.S.M.M.B.A
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Applications of fiber optics in physical protection
The purpose of this NUREG is to provide technical information useful for the development of fiber-optic communications and intrusion detection subsystems relevant to physical protection. There are major sections on fiber-optic technology and applications. Other topics include fiber-optic system components and systems engineering. This document also contains a glossary, a list of standards and specifications, and a list of fiber-optic equipment vendors
Grating devices in polymer optical fibre
This thesis presents the fabrication of fibre Bragg gratings (FBGs) and long period gratings (LPGs) in polymer optical fibre (POF). Possible fabrication techniques were discussed to fabricate FBGs in polymer optical fibre including a detailed description of the phase mask inscription technique used to fabricate FBGs in both single and multi mode microstructured polymer optical fibre (mPOF). Complementing the fabrication of polymer optical fibre Bragg gratings (POFBGs), a technique has been developed to permanently splice POF to silica optical fibre with the use of an optical adhesive. This allowed for the fabricated POFBGs to be characterised away from the optical table, allowing for application specific characterisation. Furthermore Bragg gratings have been fabricated in polymer POF with a Bragg response within the 800nm spectral region. Within this spectral region, POF predominantly manufactured from PMMA experiences considerably smaller attenuation losses when compared to the attenuation losses within the 1550nm spectral region. The effect of thermally annealing fabricated POFBGs has been studied. This included demonstrating the ability to tune the Bragg wavelength of a POFBG sensor to a desired wavelength. Thermal annealing has also been used to manufacture wavelength division multiplexed sensors with the use of a single phase mask. Finally POFBGs have been fabricated in Topas Cyclic Olefin Copolymer. Fabrication of Bragg gratings within this copolymer allowed for the first demonstration of near immunity to relative humidity whilst monitoring changes in temperature of the environment the POFBG sensor was in. Bragg gratings fabricated in the Topas copolymer demonstrated sensitivity to relative humidity which was 65 times less than that of a PMMA based POFBG sensor. This decrease in sensitivity has the potential to significantly reduce the potential of cross sensitivity to relative humidity whilst being employed to monitor measurands such as temperature and axial strain
Wavelength extension in speciality fibres
Since the invention of the laser and its first application, there has been an almost continuous
stream of new applications - many of which require specific laser sources. These
applications often require a laser source with a specific power, pulse duration, energy
and wavelength. In some cases these demands are easily met, whilst in others they have
proven rather more difficult to achieve. Traditionally, wavelength versatility has been
limited to the regions for which rare earth or gas gain media are available. These lasers
themselves can be used to generate other wavelengths through the nonlinear processes of
second and third harmonic generation, as well as sum frequency generation. Despite all
of this, there still exists a significant section of the visible and infrared spectrum for which
no convenient sources exist. This thesis is concerned with the development of sources in
these regions along with broadband sources covering significant portions of the spectrum
by themselves.
These new wavelengths are generated in a variety of speciality fibres using either
nonlinear processes or new gain media doped into standard silica fibres. Three types
of speciality fibre are used: low concentration bismuth doped fibre which provides gain
in the 1.0-1.4 μm region; photonic crystal fibres; and very high (75%) concentration
germanium fibres to generate a laser source at 2.1 μm based upon stimulated Raman
scattering. Photonic crystal fibres provide high nonlinearities and controllable dispersion
which enables the generation of broadband supercontinuum sources based upon the
interaction of many nonlinear effects. Each source will be described in depth, with
particular attention given to the underlying physics that gives rise to the source. Previous
and current limitations will be examined and an outlook of the future development of
such sources will be discussed
Characteristic and sensing properties of near- and mid-Infrared optical fibres
The work within this thesis investigates the characteristics and sensing
properties of novel near- and mid-infrared tellurite and germanate glass fibres and their
potential as sensing elements.
An asymmetric splicing method for fusion-splicing tellurite and germanate glass
fibres to standard silica fibre is demonstrated. The thermal and strain sensing properties
of these glass fibres have been studied by analysing the properties of optical fibre
Fabry-Perot cavities, which were formed when these high refractive index fibres were
spliced to silica fibre, and fibre Bragg gratings. Using fibre F-P interferometer, the
normalized thermal sensitivity of tellurite and germanate fibre was measured to be
10.76×10-6/°C and 15.56×10-6/°C respectively, and the normalized strain sensitivity of
tellurite and germanate fibre was also measured with values of 0.676×10-6 /με and
0.817×10-6 /με respectively. These results show good agreement with measurements
using fibre Bragg gratings in these fibres and are reasonably consistent with the values
predicted using available published data for glasses of similar compositions. Tellurite
and germanate glass fibres show potential as thermal sensing and load sensing elements
compared with silica fibre.
The design of an evanescent field gas sensor using tapered germanate fibre for
methane gas species detection was investigated and modelled. This model shows the
maximum gas cell length (sensing fibre length), detectable gas concentration range, and
required gas cell length range for the expected minimum detectable gas concentration of
a fibre evanescent field sensor, which gives guidance for the effective gas cell length
choosen according to different minimum detectable gas concentration requirement in
practise.
The investigation of tellurite and germanate glass fibre characteristics and
sensing properties offer guidance for their applications in sensing areas.Engineering and Physical Sciences Research Council (EPSRC
Optical fibre sensors for monitoring prestressed concrete structures in nuclear power plants
This thesis was previously held under moratorium from 20th November and 20th November 2015.Lifetime extensions of nuclear fission reactors in the UK are required to satisfy growing demands for electrical power. Many of these reactors are nearing the end of their original design life, so the continued structural integrity, particularly of the reactors' prestressed concrete pressure vessels and containments is of prime concern. Currently, a lift-off inspection of a 1 % random sample of prestressing tendons is performed at 18 month to 5 year intervals to ensure adequate prestress is present in these structures, but the extended life times are making higher resolution, more frequent and in-depth monitoring techniques more desirable. In this thesis, a method of instrumenting prestressing strands with optical fibre Bragg grating strain sensors is outlined. An all-metal encapsulation and bonding technique is developed to ensure sensor reliability under the radioactive and high-stress environments of fission reactors. This 'smart strand' is complemented by a specially developed interrogation scheme capable of continuously and automatically monitoring static and dynamic nanoscale changes in Bragg grating strain. High-resolution interrogation was achieved by extending an interferrometric demodulation technique into the static measurement regime. By modulating the strain sensitivity using a fast optical switch, strain signals could be recovered independently of noise sources using various signal processing algorithms. The application of this technology could augment the continued monitoring of concrete vessel integrity, reducing both the risks and costs associated with performing lift-off measurements in the current and next generation of nuclear reactors.Lifetime extensions of nuclear fission reactors in the UK are required to satisfy growing demands for electrical power. Many of these reactors are nearing the end of their original design life, so the continued structural integrity, particularly of the reactors' prestressed concrete pressure vessels and containments is of prime concern. Currently, a lift-off inspection of a 1 % random sample of prestressing tendons is performed at 18 month to 5 year intervals to ensure adequate prestress is present in these structures, but the extended life times are making higher resolution, more frequent and in-depth monitoring techniques more desirable. In this thesis, a method of instrumenting prestressing strands with optical fibre Bragg grating strain sensors is outlined. An all-metal encapsulation and bonding technique is developed to ensure sensor reliability under the radioactive and high-stress environments of fission reactors. This 'smart strand' is complemented by a specially developed interrogation scheme capable of continuously and automatically monitoring static and dynamic nanoscale changes in Bragg grating strain. High-resolution interrogation was achieved by extending an interferrometric demodulation technique into the static measurement regime. By modulating the strain sensitivity using a fast optical switch, strain signals could be recovered independently of noise sources using various signal processing algorithms. The application of this technology could augment the continued monitoring of concrete vessel integrity, reducing both the risks and costs associated with performing lift-off measurements in the current and next generation of nuclear reactors
Fiber-optic interconnection networks for spacecraft
The overall goal of this effort was to perform the detailed design, development, and construction of a prototype 8x8 all-optical fiber optic crossbar switch using low power liquid crystal shutters capable of operation in a network with suitable fiber optic transmitters and receivers at a data rate of 1 Gb/s. During the earlier Phase 1 feasibility study, it was determined that the all-optical crossbar system had significant advantages compared to electronic crossbars in terms of power consumption, weight, size, and reliability. The result is primarily due to the fact that no optical transmitters and receivers are required for electro-optic conversion within the crossbar switch itself
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