耗散孤子光纤激光器的特性研究

发布时间：2018-01-12 18:46

本文关键词：耗散孤子光纤激光器的特性研究　出处：《电子科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：单脉冲能量是被动锁模光纤激光器的一项重要指标,为了能够大幅度提高锁模光脉冲的能量,人们提出了各种光纤激光器方案。近年来,工作在正色散区的耗散孤子锁模光纤激光器引起了研究人员的广泛关注。与传统孤子相比,耗散孤子具有完全不同的脉冲形成机制和物理特性,它可以突破传统孤子所受到的能量限制,有效克服光波分裂,从而实现更高能量的锁模脉冲输出,因此,研究耗散孤子光纤激光器具有重要的科学意义和应用价值。本文主要研究内容和结果如下:首先,构建了正色散腔非线性偏振旋转(NPR)被动锁模掺铒光纤激光器,实验获得了稳定的耗散孤子锁模脉冲,其中心波长、光谱宽度、脉冲宽度和重复频率分别为1570.1 nm、22 nm、4.48 ps和2.322 MHz,脉冲具有强烈的啁啾。此外,通过调节泵浦功率和偏振控制器,实验观察到了由调制不稳定性导致的耗散孤子光谱边带,并利用调制不稳定性边带特性与色散的关系,估算出了腔内净色散。通过优化谐振腔结构,获得了2到7阶的谐波锁模耗散孤子脉冲,分析了谐波锁模脉冲形成的物理机制。此外,实验还观察到了束缚态耗散孤子。其次,采用“脉冲跟踪”法对正色散腔NPR被动锁模光纤激光器进行数值仿真研究。数值模拟了激光器谐振腔内光脉冲的形成和演化过程,分析了光脉冲在谐振腔内的偏振演化特性,讨论了激光器的工作参数对输出脉冲特性的影响。另外,数值仿真了激光器输出的耗散孤子在腔外负色散光纤中的脉冲压缩过程,通过优化光纤长度,将皮秒耗散孤子脉冲压缩至370 fs。最后,数值模拟研究了基于石墨烯的正色散腔被动锁模光纤激光器中耗散孤子的矢量特性。通过改变谐振腔内光纤的双折射拍长,仿真得到了不同偏振旋转锁定周期的偏振旋转锁定矢量耗散孤子,研究了其在腔内的偏振态演化过程,并与已报道的实验结果进行了对比分析。另外,通过改变谐振腔内的双折射拍长和小信号增益系数,仿真还得到了偏振锁定矢量耗散孤子。数值研究表明,偏振旋转锁定矢量耗散孤子和偏振锁定矢量耗散孤子是谐振腔内线性双折射和非线性双折射共同作用的结果。
[Abstract]:Monopulse energy is an important index of passive mode-locked fiber laser. In order to improve the energy of mode-locked fiber laser, a variety of optical fiber laser schemes have been proposed in recent years. Dissipative soliton mode-locked fiber lasers operating in the normal dispersion region have attracted wide attention. Compared with the traditional solitons, the dissipative solitons have completely different pulse formation mechanisms and physical characteristics. It can break through the energy limitation of the traditional soliton and overcome the splitting of optical wave effectively, so that the output of mode-locked pulse with higher energy can be achieved. The study of dissipative soliton fiber laser has important scientific significance and application value. The main contents and results of this paper are as follows: first. A passively mode-locked erbium-doped fiber laser with a positive dispersion cavity with nonlinear polarization rotation has been constructed. A steady dissipative soliton mode-locking pulse with center wavelength and spectral width has been obtained experimentally. The pulse width and repetition rate are 1570.1 nm ~ 22 nm ~ (-1) ~ 4.48 PS and 2.322 MHz, respectively, and the pulse has strong chirp. By adjusting the pump power and the polarization controller, the dissipative soliton spectral sideband caused by modulation instability is experimentally observed, and the relationship between the modulation instability sideband characteristic and the dispersion is used. The net dispersion in the cavity is estimated. By optimizing the structure of the resonator, the second to seventh order harmonic mode-locking dissipative soliton pulses are obtained, and the physical mechanism of the harmonic mode-locking pulses is analyzed. The bound state dissipative solitons are also observed. The pulse tracking method is used to simulate the passive mode-locked fiber laser with normal dispersion cavity (NPR), and the formation and evolution of the optical pulse in the resonator are numerically simulated. The polarization evolution characteristics of optical pulse in resonator are analyzed, and the influence of laser operating parameters on the characteristics of output pulse is discussed. The pulse compression process of the laser output dissipative soliton in the optical fiber with negative dispersion outside the cavity is simulated numerically. By optimizing the length of the fiber, the picosecond dissipative soliton pulse is compressed to 370 fs. finally. The vector characteristics of dissipative solitons in a positive dispersion cavity passively mode-locked fiber laser based on graphene are studied numerically by changing the birefringence beat length of the fiber in the resonator. The polarization rotation locking vector dissipative solitons with different polarization rotation locking periods are obtained by simulation. The polarization state evolution in the cavity is studied and compared with the reported experimental results. By changing the birefringence beat length and the small signal gain coefficient in the resonator, the polarization locking vector dissipative soliton is obtained. Polarization rotation locking vector dissipative solitons and polarization locked vector dissipative solitons are the results of the interaction of linear birefringence and nonlinear birefringence in resonator.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN248

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