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Study On The Active Mode-locked Fiber Ring Laser Based On SOA

Posted on:2006-02-20Degree:MasterType:Thesis
Country:ChinaCandidate:W Y YangFull Text:PDF
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Optical signal sources with high repetition rate and the tunable central wavelength play an important role in the high-bit-rate and all-optical communication system. Actively mode-locked ring lasers taking erbium-doped fiber as the gain medium have attracted much attention for generating ultra-short and transform-limited optical pulses. However, the output pulse is inherently unstable even unlocking because of the fluctuations of polarization state and cavity-length drift caused by mechanical vibration and thermal fluctuations. To solve the problem, many methods have been proposed. But, it will result in the more complex and expensive system.Based on the semiconductor optical amplifiers (SOAs) which have the advantages of the fast response speed, good stability, easy to integrate and insensitive polarization, a novel harmonic mode-locked fiber ring laser based on SOA has been presented in this paper. This scheme includes two SOAs, one is named modulation SOA, the other is named gain SOA. The influence of SOAs on optical pulse can be described by the rate equations including gain compression and asymmetric distribution, and the pulse amplitude evolution in the fiber can be described by the Schrodinger equation. Combined the self-reproduction theory, the stable mode-locked pulses can be obtained by numerical simulation, thus the peak power and the pulse width of mode-locked pulses can be investigated.In this paper, the influence of the bias currents on the shape of mode-locked pulses and the wavelength tunable range through inserting a filter are investigated. The results show that, firstly, the bias currents of two SOAs affect obviously the shapes of...
Keywords/Search Tags:Semiconductor Optical Amplifier (SOA), Cross-gain modulation (XGM), Mode-locked laser, Bias current, Peak power
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