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The effects of noise in CATV distribution networks with star couplers and fiber amplifiers /Chen, David Yong, January 1994 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 84-86). Also available via the Internet.
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Nanostructured optical fibre for use as miniature surface-enhanced raman scattering sensorsWhite, Daniel Joshua. January 2008 (has links)
Thesis (PhD) - Swinburne University of Technology, Centre for Atom Optics and Ultrafast Spectroscopy, 2007. / Thesis submitted in fulfilment for the degree of Doctor of Philosophy, Centre for Atom Optics and Ultrafast Spectroscopy, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, 2008. Typescript. Bibliography: p. 151-160.
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All-optical gain switching of erbium-doped fibre amplifiers.Cheney, Glenn P. (Glenn Peter), Carleton University. Dissertation. Engineering, Electrical. January 1992 (has links)
Thesis (M. Eng.)--Carleton University, 1993. / Also available in electronic format on the Internet.
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Microscopic characterisation of fibre Bragg gratingsKouskousis, Betty. January 2009 (has links)
Thesis (Ph.D.)--Victoria University (Melbourne, Vic.), 2009.
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Fiber optic confocal microscope in vivo precancer detection /Carlson, Kristen Dawn, January 1900 (has links) (PDF)
Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.
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Axial strain effects on optical fiber mode patterns /Srinivas, K. T., January 1987 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1987. / Vita. Abstract. Includes bibliographical references (leaves 41-42). Also available via the Internet.
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[en] SOLITON PROPAGATION IN OPTICAL FIBRES ANALYSIS / [pt] ANÁLISE DA PROPAGAÇÃO DE SÓLITONS EM FIBRAS ÓTICASTANIA GORNSZTEJN 31 July 2006 (has links)
[pt] Neste trabalho, a propagação de sólitons em fibras óticas
é analisada através de simulação numérica da equação não
linear de Schrödinger, a qual descreve a propagação de
pulsos óticos em fibras monomodo do tipo degrau. Uma vez
que soluções analíticas para esta equação só podem ser
obtidas em alguns casos específicos, implementaram-se dois
métodos numéricos, possibilitando a análise da evolução de
diferentes formas de pulsos incidentes ao longo de fibras
com propriedades diversas de atenuação, dispersão e não
linearidades. O método da propagação de Raios, cujo
desempenho mostrou-se superior ao do método da série de
Fourier, foi o escolhido para a obtenção dos resultados
aqui apresentados.
Várias características do sóliton fundamental, dos
sólitons de ordens superiores, dos sólitons escuros e do
fenômeno da interação entre pulsos adjacentes são
apresentadas e discutidas, levando-se em consideração as
possíveis implicações no desempenho de sistemas óticos.
Contrabalançando os efeitos da dispersão da fibra com os
efeitos não lineares da automodulações de fase, o que
permite sua propagação sem alteração de forma, os sólitons
encontram potencial aplicação na transmissão de altas
taxas a longas distâncias. / [en] In this work, soliton propagation in optical fibres is
analysed by means of numerical simulation of the nonlinear
Schrödinger equation, which governs optical pulse
propagation in step-index monomode fibres. Since analytic
solutions to this equation are admitted only for some
specific cases, two numerical methods have been
implemented in order to study the evolution of different
kinds of input pulses, under the effects of attenuation,
dispersion and nonlinearities. Showing a better
performance than the Fourier Series Method in a
comparative test, the Beam Propagation Method has been
chosen to obtain the results here presented.
Many characteristics of the fundamental, higher order and
dark solitons, as well as interaction phenomena between
adjacent pulses, are investigated, taking into account
possible implications on optical systems performance. By
properly counteracting the effects of fibre dispersion and
nonlinearities, solitons can propagate without changing
its shape, finding potential application in high bit-rate
long distance optical communication systems.
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Gain equalization of erbium doped fibre amplifiers with tuneable long-period gratingsNhlapo, Thabiso J. 26 February 2009 (has links)
M.Ing. / This thesis is about the gain equalization of erbium doped fibre amplifiers (EDFA), which is a key technology for enabling wavelength-division multiplexed (WDM) optical communication systems. In order to flatten dynamically the EDFA gain spectrum, a tuneable long-period grating filter was demonstrated. Long-period gratings were fabricated by using a KrF excimer laser combined with the metal amplitude mask technique. The transmission spectrum characteristic of the long- period grating was simulated theoretically by the coupled-mode theory. The coupling between the core and cladding modes of the long-period grating was investigated both experimentally and theoretically. The EDFA was constructed by using the forward pumping configuration consisting of pump laser source, WDM couplers, an optical isolator, and the erbium-doped fibre. The EDFA was characterized theoretically and experimentally for WDM applications. The tuneable long-period grating filter design is based on the tuneable coupler that uses the Mach-Zehnder interferometer configuration. The tuneable filter was demonstrated by equalizing the EDFA gain spectrum and the amplified spontaneous emission (ASE) source. The main advantage of this filter compared to other optical filters is its tuneability of the attenuation over a wide range of pump power.
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Dispersion compensation in wavelength-division multiplexed optical fibre linksSaleh, Kawaya Shako 26 February 2009 (has links)
M.Ing. / Lightwave systems used in the core transport network of telecommunication systems operate in the second transmission window. The 1550 nm wavelength region exhibits the lowest attenuation coefficient, thus expanding the repeater distance in the network. However, the influence of the large dispersion coefficient associated with the second transmission window limits the operating speed of the network to 2.5 Gbit/s or less. In order for the network to operate at higher bit-rate, a dispersion management scheme is needed. In this research, the performance of negative dispersion fibre used as a dispersion compensating module is investigated. The negative dispersion fibre used in this study was the AVANEX PureForm DCM. The dispersion coefficient of the DCM measured at 1525 nm, 1545 nm and 1565 nm were given as -918 , -987 and -1047 respectively. The optimal operating condition of the DCM was obtained by considering various dispersion management configurations i.e. post-compensation, pre-compensation and symmetric compensation. The DCM was tested on a single span, single channel system operating at a speed of 10 Gbit/s with the transmitting wavelength of 1551.2 nm, over 60 km of convention single mode fibre. Furthermore, the performance of the system at 55 km and 65 km were also used to examine the results for the over- and under compensation links respectively. The results obtained for 100% dispersion cancellation for the pre-, post- and symmetric configuration showed an increase in the extinction ratio of 2.09 dB, 2.72 dB and 2.37 dB respectively. Similarly, the Q-factor was estimated to equal 13.67, 11.296 and 13.167 respectively. The results indicate similar performance for all the configurations considered, analysis of the eye-diagrams reveals that the post-compensation configuration would ultimately yield the best results. This is due to the fact that eye diagram recovered from this setup has minimal deformation. The experiments for an extremely over-compensated link, i.e. 40 km, showed an increase from 9.49, obtained with no compensation, to 10.63. However, for the extremely under-compensated link i.e. 80 km, the extinction ratio only manages to improve from 4.88 dB to 8.63 dB.
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Experimental study of photosensitivity of optical fibreJoubert, Wietz Louwrens 06 February 2012 (has links)
M.Ing. / Bragg gratings exist due to permanent changes in the refractive index introduced in the fibre through exposure to ultraviolet radiation. Standard telecommunications fibre (SMF-28) is only slightly photosensitive at 248 nm irradiation. A comparative study of different photosensitization techniques is undertaken on the basis of the desired photosensitivity characteristics and efficiency of the technique used. The analytical method is used to determine valuable properties of fibre Bragg gratings. The bandwidth and maximum reflectivity of the fibre Bragg grating is dependant on the change of refractive index and is determined analytically. Obtaining very high reflectivity and bandwidth (~lnm) can only be achieved with highly photosensitive optical fibre where refractive index changes of~ 1 o-3 are possible. The change of the refractive index in the optical fibre is related to the phase change by: A new interferometric measurement technique based on this assumption allows the direct measurement of photosensitivity. This technique is modelled with a modified Layer Peeling algorithm. Standard telecommunications fibre was exposed to high-pressure (26B - 160B) hydrogen for several days. This increased the photosensitivity of the optical fibre significantly. The photosensitivity of the fibre is directly dependent on the hydrogen concentration inside the fibre. Refractive index changes, M ~ 1.3x10-3 were achieved in germanium doped fibre and M ~ 5x10-3 in germanium/boron codoped fibre. The knowledge of the hydrogen concentration inside the fibre is important in studying photosensitivity, transmission losses and the wavelength drift after Bragg grating manufacturing. The diffusion proceeds interstitially with no significant chemical interaction. A hydrogen diffusion model was developed based on the transfer of heat between two objects. Although the photosensitivity phenomenon was discovered in optical fibre more than 20 years ago, no complete physical explanation exist for it at present. We agree that stress relaxation and/or compaction are the main reasons for photosensitivity in optical fibre but also that it is still a complex and multifaceted phenomenon. A study of the thermal decay of fibre Bragg gratings suggests that fibre Bragg gratings written in hydrogen loaded fibre is less thermally stable than gratings written in germanium doped fibre. The analysis of accelerated ageing will predict the thermal stability of the Bragg grating over time.
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