高调制深度饱和吸收体被动锁模光纤激光器的研究

发布时间：2018-05-04 18:26

本文选题：光纤激光器 + 饱和吸收体　；参考：《湖南大学》2015年硕士论文

【摘要】：被动锁模光纤激光器具有稳定性好、效率高、系统紧凑等优势,在光纤通信、遥感、激光雷达、光谱分析和军事等方面具有广泛应用,是目前超快激光研究的热点之一。为了获得高峰值功率、超快的锁模激光输出,光纤激光器的谐振腔和光学元件需要仔细选择。其中,可饱和吸收体是被动锁模光纤激光器中的关键器件,它要求非线性材料具有可控的非线性吸收能力、快的响应和低的损耗。除此之外,调制深度也是可饱和吸收体的关键参数之一,高的调制深度可以增强消减脉冲边缘的效果,有利于获得超短脉冲,而且可以有效提高超快激光器的稳定性。本论文围绕如何获得短脉冲、稳定工作的被动锁模光纤激光器,理论结合实验研究了高调制深度饱和吸收体对被动锁模光纤激光器输出特性的影响。主要工作如下:第一,数值模拟了光通信波段可饱和吸收体参数对被动锁模光纤激光器输出特性的影响,并基于拓扑绝缘体可饱和吸收体实现了亚皮秒的超快激光输出。基于Ginzburg-Landau方程,数值模拟了可饱和吸收体对被动锁模光纤激光器输出特性的影响。基于Bi2Te3可饱和吸收体,设计并搭建了被动锁模掺Er的环形腔光纤激光器,并实现稳定的脉冲输出。泵浦功率到达85.4 m W时,光纤激光器进入自启动的状态;泵浦功率调至500 m W时,我们获得重复频率为13.14 MHz、脉宽约505 fs的锁模孤子脉冲输出。通过不断调控偏振控制器,观察到光纤激光器输出脉冲的中心波长能够在1570.45到1572.32 nm之间连续调谐。第二,数值模拟了近零色散情况下掺铥被动锁模光纤激光器的输出特性,为优化设计中红外超快光纤激光器提供了指导。基于Ginzburg-Landau方程,数值研究了饱和吸收体参数(调制深度、饱和功率和非饱和吸收损耗等)对被动锁模光纤激光器输出脉冲特性的影响。在谐振腔净腔色散为 0.008 ps2时,获得了稳定的孤子脉冲输出。数值模拟结果表明:高调制深度、低饱和功率的饱和吸收体能够得到更窄的孤子脉冲。
[Abstract]:Passive mode-locked fiber laser has the advantages of good stability, high efficiency and compact system. It has been widely used in optical fiber communication, remote sensing, lidar, spectral analysis and military. In order to obtain high peak power and ultra-fast mode-locked laser output, the resonator and optical components of fiber laser need to be carefully selected. The saturable absorber is the key device in the passive mode-locked fiber laser. It requires the nonlinear material to have controllable nonlinear absorption ability, fast response and low loss. In addition, modulation depth is also one of the key parameters of saturable absorber. High modulation depth can enhance the effect of reducing pulse edge, which is helpful to obtain ultrashort pulse, and can effectively improve the stability of ultra-fast laser. In this paper, the effect of high modulation depth saturated absorber on the output characteristics of passive mode-locked fiber laser with short pulse and stable operation is studied theoretically and experimentally. The main work is as follows: first, the influence of saturable absorber parameters in optical communication band on the output characteristics of passive mode-locked fiber laser is numerically simulated, and the subpicosecond ultra-fast laser output is realized based on the topologically insulator saturable absorber. Based on Ginzburg-Landau equation, the effect of saturable absorber on the output characteristics of passive mode-locked fiber laser is numerically simulated. Based on the Bi2Te3 saturable absorber, a passively mode-locked er doped ring cavity fiber laser is designed and constructed, and the stable pulse output is realized. When the pump power reaches 85.4 MW, the fiber laser enters the state of self-start, and when the pump power is adjusted to 500MW, we obtain a mode-locked soliton pulse with a repetition rate of 13.14 MHz and a pulse width of about 505 fs. By continuously adjusting the polarization controller, it is observed that the central wavelength of the output pulse of the fiber laser can be continuously tuned from 1570.45 nm to 1572.32 nm. Secondly, the output characteristics of thulium doped passively mode-locked fiber laser with near-zero dispersion are numerically simulated, which provides guidance for optimizing the design of ultra-fast infrared fiber laser. Based on Ginzburg-Landau equation, the effects of saturation absorber parameters (modulation depth, saturation power and unsaturated absorption loss) on the output pulse characteristics of passive mode-locked fiber laser are numerically studied. A stable soliton pulse output is obtained when the cavity dispersion is 0.008 ps2. Numerical simulation results show that a narrower soliton pulse can be obtained by a saturated absorber with high modulation depth and low saturation power.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN248

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