石墨烯锁模掺铒光纤激光器的研究

发布时间：2018-01-07 21:14

本文关键词：石墨烯锁模掺铒光纤激光器的研究　出处：《哈尔滨工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：光纤通信在最近几十年快速发展,已经深入日常生活的方方面面。而光纤通信的理想光源就是激光,同时光纤具有体积小、损耗低等优点,所以关于光纤激光器方面的研究大量涌现,并且取得喜人的成果。但是随着科技的进一步发展,传统的光纤激光器因其脉冲宽度的限制而不能携带更多的信息而逐渐不能满足日益增长的社会需要。因此,超快激光器又成为研究的热点,与此同时,石墨烯的出现为锁模激光器提供了新型的饱和吸收材料,其饱和吸收特性可以进行锁模进而使光脉冲压窄,甚至可以达到飞秒级。在此背景下,作者采用石墨烯作为可饱和吸收体,研究石墨烯锁模光纤激光器的输出特性以及模型仿真,具体做了如下工作:在实验方面,首先采用改进脉冲激光沉积法将石墨烯转移到光纤连接头上。改进脉冲激光沉积法是将光纤连接头一端浸于石墨烯溶液中,光纤连接头的另一端通过耦合器接到泵浦激光器上,保持功率恒定输出数分钟后,功率计的读数突然有一个跳变,这时说明石墨烯已经附着在光纤连接头的端口处,沉积已经完成。其次则是搭建了环形光纤激光器,在环形腔内引入石墨烯可饱和吸收体后,适当调节偏振控制器,激光器就有稳定光孤子脉冲输出。输出的脉冲宽度为皮秒级,脉冲间隔为520 ns,重复频率为1.92 MHz,射频谱的幅值为75 dB,中心波长在1557.3 nm,并且光谱两翼位置出现Kelly边带,输出功率为3.2 mW。在理论研究方面,则是应用麦克斯韦方程组建立描述本实验的方程,通过此方程来仿真石墨烯锁模掺铒光纤激光器的输出特性。方程推导的主要步骤是,先将麦克斯韦方程组化简为波动方程,然后对波动方程做傅里叶变换,分离出与幅度相关的纵模信息,再将纵模按泰勒公式展开到二阶,最后再做反傅里叶变换就可以得到所需的方程。在推导方程的过程中,我们采用的四个化简条件使方程更简洁、更容易求解。由此仿真得到了四个结论,这四个结论从时域和频域两方面验证了实验的输出特性。最后,在时域上对比实验和仿真,证明了输出的脉冲为孤子脉冲;在频域上分析了Kelly边带产生的原因,并且将实验输出的光谱形状与仿真得到光谱形状进行了对比,两者基本吻合。实验总体达到了预期效果,理论仿真也对实验的正确性进行了验证。
[Abstract]:The rapid development of optical fiber communication in recent decades, has penetrated every aspect of daily life. And the optical fiber communication and optical fiber laser is the ideal light source, has the advantages of small size, low loss, so the research on fiber lasers have emerged, and made gratifying achievements. But with the further development of science and technology, the traditional optical fiber laser because of the pulse width limit and can not carry more information and gradually cannot meet the growing needs of the society. Therefore, ultrafast laser also has become a hot research topic, at the same time, the appearance of graphene mode-locked lasers offer new saturable absorption materials, the absorption can be locked and the light pulse narrow, can even reach the femtosecond level. Under this background, the author using graphene as a saturable absorber, of mode-locked fiber lasers with graphene Output characteristics and simulation model, the specific contents are as follows: in the experiment, the improvement of pulsed laser deposition of graphene will be transferred to the optical fiber connector. The improved pulsed laser deposition is the optical fiber connector end immersed in graphene solution, the other end of the optical fiber connector through the coupler to the pump laser. Maintain a constant output power after a few minutes, the power meter readings suddenly have a jump, then that graphene has been attached to the port in the optical fiber connector, deposition has been completed. The second is the ring fiber laser was constructed. The introduction of graphene saturable absorber in the annular cavity after adjusting the polarization controller, a laser will the stable soliton pulse output. The output pulse width for picosecond, pulse interval of 520 ns, the repetition rate is 1.92 MHz, the amplitude of the RF spectrum is 75 dB, 1557 in the center wavelength .3, nm, and Kelly spectra of the wing positions sideband, the output power is 3.2 mW. in the aspect of theory research, it is the application of Maxwell equation to describe the equation, through this equation to simulate the output characteristics of graphene mode-locked erbium-doped fiber laser. The main steps of the equation is the Maxwell equations. The simplification for the wave equation, then Fu Liye transform of wave equation, isolated longitudinal mode information and amplitude correlation, then the longitudinal model according to the Taylor formula to order two, and finally do the inverse Fu Liye transform can get the desired range. In the equation, we use the four. Simple conditions make the equation more concise, easier to solve. This simulation has got four conclusions, these four conclusions verify the output characteristics experiment from two aspects of time domain and frequency domain. Finally, in the time domain contrast experiment and simulation, proved The output pulse for soliton pulse in frequency domain; analyzed the reason of Kelly band is generated, and the spectral shape and the spectral shape of simulation output are compared, the basic agreement between the two. The overall experiment achieves the desired results, the correctness of the theory simulation experiment is verified.

【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN248

【参考文献】