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Research On The Theory And Applications Of The Novel Actively Mode-locked Fiber Laser

Posted on:2016-02-04Degree:DoctorType:Dissertation
Country:ChinaCandidate:R X WangFull Text:PDF
GTID:1108330482960397Subject:Communication and Information System
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High-repetition-rate, high-quality, low-noise and broad-spectrum actively mode-locked fiber laser (AMFL) have drawn great interests in their potential applications in DWDM, OTDM, ultra-wideband signal processing and many other areas. However, difficulties of low pulse energy, poor stability, limited spectrum and long cavity must be overcome.In this dissertation, we utilized novel AMFLs and pulse shaping mechanism to solve these problem, and use these new structures for stable radio frequency delivery and high-repetition-rate wideband optical frequency comb generation.We firstly study the characteristics of output pulses of the AMFL, investigate the transient states during self-starting and pulse shaping process, and confirm the soliton pulse shaping in anomalous dispersion AMFL. We also find that the AMFL suffers supermode noise and caivity length shifting.The supermode noise is the main noise of the AMFLs, pulse-power-limiting effect is achieved by a pulse feed-forward techinque, which can suppress the supermode noise of the AFML. The supermode-suppression ratio is larger than 81 dB without changing the cavity structure, and the pulse-to-pulse timing jitter is 22 fs. By combination of dispersion-tuned cavity and the pulse feed-forward technique, the laser presents excellent long-term stability. Besides, this structure is used to transfer ultra-stable microwave frequency over long fiber link.Fast saturable absorption can be realized by the combination of a dual-drive modulator and a feed-forward path, which is employed for fundamental soliton mode locking. Experimentally, under high-frequency modulation, the laser generates 1.4-ps transform-limited soliton pulse train. For further increasing the pulse energy, dissipative soliton (DS) pulse shaping in an AMFL is proposed for the first time. High energy DS is realized in the all-normal-dispersion cavity with special modulation profile. We investigate the transient states of pulse in a DS-AMFL during self-starting and pulse shaping process. The laser generates 1.6-nJ DS, which is larger than conventional soliton dozens of times. Besides, the laser has excellent tunability, its wavelength can be tuned over 50 nm by simply adjusting the driving frequency.Based on the DS in active mode locking, the concept "linear dissipative soliton (LDS)" is proposed. The LDS pulse shaping is realized by the stretched-lens technique in a nonlinearity-free cavity, which breaks through the bandwith limitation of the conventional high-repetition-rate AMFL. The pulse properties and pulse shaping process are demonstrated and analyzed in detail. Experimentally, the laser generates 10-GHz pulse train with 825-fs pulse duration and 11.6-nm spectral bandwidth.High-reatitition-rate broadband stable optical frequency comb is generated by injection-locking and cavity feed-back control in a LDS-AMFL. The 3-dB bandwidth of the 10GHz optical frequency comb is 7.6 nm with nearly 100 comb lines. Without fiber nonlinearity Kerr effect, the LDS is a promising way for high-repitition-rate broadband optical frequency comb generation with a compact structure.
Keywords/Search Tags:Actively mode-locked fiber laser, Pulse feed-forward, Pulse shaping, Dissipative soliton, Optical frequency comb
PDF Full Text Request
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