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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Developments of Narrow-Linewidth Q-switched Fiber Laser, 1480 nm Raman Fiber Laser, and Free Space Fiber Amplifier

Zhou, Renjie January 2011 (has links)
In the first chapter, a Q-switched fiber laser that is capable of generating transform-limited pulses based on single-frequency fiber laser seeded ring cavity is demonstrated. The output pulse width can be tuned from hundreds of nanoseconds to several microseconds. This Q-switched ring cavity fiber laser can operate over the whole C-band. In addition, a theoretical model is developed to numerically study the pulse characteristics, and the numerical results are in good agreements with the experimental results. In the next chapter, a Raman fiber laser is developed for generating signal at 1480 nm. Initial experimental results has demonstrated generating of Raman laser at 1175 nm, 1240 nm, 1315 nm, and 1395 nm wavelength. Finally, a free space fiber amplifier is studied both theoretically and experimentally. The experimental work has demonstrated signal coupling efficiency up to 90% in the NP highly Er/Yb co-doped phosphate fiber.
2

Laser Raman à fibra operando na banda O em regime de acoplamento passivo de modos utilizando nanotubos de carbono como absorvedores saturáveis

Steinberg, David 27 August 2015 (has links)
Made available in DSpace on 2016-03-15T19:38:55Z (GMT). No. of bitstreams: 1 DAVID STEINBERG.pdf: 3031041 bytes, checksum: e320f0c21b75ca5bdd5a63f93fa6dd1d (MD5) Previous issue date: 2015-08-27 / Fundo Mackenzie de Pesquisa / In this thesis, for the first time we present results of passively-mode-locking O-band Raman fiber laser operating at 1310 nm by using carbon nanotubes as saturable absorber. The first results were obtained for an experimental setup based on single mode fiber (SMF) with laser operating near zero fiber dispersion at 1310 nm at anomalous regime. In this same configuration, a study of pulse duration shortening in terms of intracavity dispersion management with dispersion shifted fiber lengths (DSF) was performed. Replacing the SMF by a highly doped germanium fiber as gain medium of Raman fiber laser, operation was shifted to normal dispersion regime and passive mode-locking was also generated. In this laser, a study of pulse duration shortening in terms of gain medium length reduction was performed and the picosecond pulse regime of the laser could be estimated. We also present a brief comparison between the two dispersion regimes of the Raman fiber laser and passive mode-locking results obtained with different diameters of carbon nanotubes as saturable absorbers. / Nesta tese, apresentamos pela primeira vez resultados do acoplamento passivo de modos em um laser Raman à fibra operando em 1310 nm na banda O, utilizando nanotubos de carbono como absorvedor saturável. Os primeiros resultados foram obtidos de uma configuração experimental baseada totalmente em fibra monomodo padrão (SMF) com o laser operando próximo ao zero de dispersão da fibra em 1310 nm, porém em regime anômalo. Nesta mesma configuração, um estudo do encurtamento da duração do pulso em função do gerenciamento da dispersão intracavidade com comprimentos de fibra de dispersão deslocada (DSF) foi realizado. Substituindo a SMF por uma fibra altamente dopada com germânio como meio do ganho do laser Raman, a operação do laser foi deslocada para o regime de dispersão normal e o regime de acoplamento passivo de modos também foi gerado. Neste laser, um estudo do encurtamento da duração do pulso em função da redução do comprimento do meio de ganho foi realizado e a operação do acoplamento passivo de modos do laser em regime de picossegundos pôde ser estimada. Também apresentamos uma breve comparação entre os dois regimes de dispersão do laser Raman à fibra e resultados do acoplamento passivo de modos obtidos com diferentes diâmetros de nanotubos de carbono como absorvedores saturáveis.

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