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Study On Two Features Of The Optical Fiber Laser

Posted on:2008-01-27Degree:MasterType:Thesis
Country:ChinaCandidate:S L LiFull Text:PDF
GTID:2178360215477004Subject:Optics
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The research on fiber laser plays an important role in the development of optical communication technology nowadays. Bi-stable laser is the key device in optical switching and optical logic. Multiwavelength laser plays a key role in the technology of WDM. In this thesis, we will study the bistability and multiwavelength phenomenon in fiber lasers.In our experiment, we observed that optical bistability can exist even in a simple fiber laser employing erbium-doped fiber (EDF) as a gain medium. Based on the traditional three-level model and by introducing "useless pump loss" into it, we can build a model to prove that this bistability's existance. The calculation result fits our experiment well. Moreover, by building the theory of optical bistability in fiber laser, we can also find out the dependence of the bistability on various parameters, such as the length of the EDF. These results provides a theoretical basis for us to control the bistability in a fiber laser. Lyot-Sagnac filter is composed by several segments of polarization maintaining fiber (PMF). It can be used as a filter for any grid spacing wanted. If polarization controllers (PC) are added into this filter, the grid spacing obtained can be switched from one to another by adjusting these PCs. The semiconductor optical amplifier has the feature of inhomogeneous broadening, which makes it an ideal gain medium for constructing multiwavelength fiber lasers. A novel multiwavelength fiber laser employing a semiconductor optical amplifier within a fiber ring cavity is proposed on the basis of the theoretical analysis of the Lyot-Saganc filter with two segments of PMF. This fiber laser can generate 18 multiwavelength lasers with signal-to-noise ratio (SNR) 30dB, ranging from 1556nm to 1577nm. The grid spacing of the output laser can be selected between ITU grid spacings: 0.4nm and 0.8 nm, at room temperature. This kind of fiber lasers has good tunability and stability with a high signal-to-noise ratio. It can be used in the WDM networks employing an interleaved waveband concept.
Keywords/Search Tags:laser technique, fiber laser, optical bistability, multiwavelength laser, Lyot-Sagnac filter, semiconductor optical amplifier
PDF Full Text Request
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