耗散孤子光纤激光器的研究

发布时间：2018-06-22 06:57

本文选题：耗散孤子 + 碳纳米管　；参考：《江西师范大学》2015年硕士论文

【摘要】：做为20世纪最为重要的发明之一,激光技术不仅仅是改变了人们的生活方式,它还为人类探索物质更本质特性中提供了强有力的工具。所以在随后发展的四五十年时间里,各个种类的激光器层出不穷,例如固体激光器、液体激光器、气体激光器、半导体激光器、染料激光器、准分子激光器和光纤激光器等。其中,光纤激光器以其高转换效率、结构紧凑、高光束质量、高稳定性、经济适用等特点,受到越来越多学者的青睐。然而在光纤激光器的发展历史中,传统孤子产生于非线性系统中,光脉冲存在于极小模场面积的纤芯中,在较小的输入泵浦功率下就可能产生较高的峰值功率密度,高的峰值功率密度会增加传输过程中的非线性效应,积累过量的非线性相移使光波分裂,所以传统孤子的能量都不太高。耗散孤子产生于非线性系统中,它的产生主要由增益、损耗、色散、非线性等综合效应决定,其形成规律与传统的孤子脉冲完全不同,它可以在不发生光波分裂的前提下,突破传统的孤子光纤激光器所受到的能量限制。本文的具体研究内容如下所述:1.理论研究方面,阐述了耗散孤子被动锁模光纤激光器中耗散孤子产生的具体机制及耗散孤子的特点,同时较为详细的阐述光纤激光器中色散、非线性和增益三个关键要素对于耗散孤子的影响,并在此基础上介绍了描述锁模光纤激光器中脉冲传输特性的Ginzburg-Landau方程。2.通过实验和数值模拟在碳纳米管做为饱和吸收体的色散管理光纤激光器中实现稳定的耗散孤子锁模脉冲输出。常见的耗散孤子频谱图形状近似为矩形,且具有陡峭的边沿。在实验中发现耗散孤子脉冲的啁啾近似为线性。此外,对该类型耗散孤子脉冲特性、产生机理及其演化规律进行理论分析和数值模拟,在误差范围内,数值模拟结果与实验结果基本一致。3.对脉冲在色散管理下的传输进行的数值模拟,研究了腔内不同净色散下耗散孤子的演化过程。与此同时,改变数值模拟中饱和吸收体的参数,研究了耗散孤子特性的相应变化。最后,在系统中加入了带通滤波器,并且改变带通滤波器的带宽,研究其对耗散孤子相应特性的影响。4.数值模拟了在全正色散光纤激光器中稳定暗孤子和明暗孤子的形成机理,通过改变饱和吸收体的参数和单模光纤的长度,研究饱和吸收体和腔内净色散值对暗孤子特性的影响
[Abstract]:As one of the most important inventions in the 20th century, laser technology has not only changed people's way of life, but also provided powerful tools for human beings to explore the more essential properties of matter. Therefore, in the subsequent development of 40 or 50 years, various types of lasers, such as solid-state lasers, liquid lasers, gas lasers, semiconductor lasers, dye lasers, excimer lasers and fiber lasers, and so on. Among them, fiber laser is more and more popular for its high conversion efficiency, compact structure, high beam quality, high stability, economic applicability and so on. However, in the history of fiber laser, the traditional soliton is produced in the nonlinear system, the optical pulse exists in the core of the minimum mode field area, and the peak power density may be higher when the input pump power is small. The high peak power density will increase the nonlinear effect in the transmission process, and accumulate excessive nonlinear phase shift to split the optical wave, so the energy of the traditional soliton is not too high. The dissipative solitons are produced in nonlinear systems, which are mainly determined by the gain, loss, dispersion, nonlinearity and so on. The formation law of the dissipative solitons is completely different from that of the traditional soliton pulses. Break through the energy limitation of the traditional soliton fiber laser. The specific contents of this paper are as follows: 1. In theory, the mechanism and characteristics of dissipative soliton in passive mode-locked fiber laser are described, and the dispersion in fiber laser is described in detail. The effects of nonlinear and gain factors on the dissipative soliton are discussed, and the Ginzburg-Landau equation .2which describes the pulse propagation characteristics in a mode-locked fiber laser is introduced. The steady output of dissipative soliton mode-locked pulse is achieved in a dispersion-managed fiber laser using carbon nanotubes as a saturated absorber by experiment and numerical simulation. The common dissipative soliton spectrum is approximately rectangular in shape and has steep edges. It is found that the chirp of the dissipative soliton pulse is approximately linear. In addition, theoretical analysis and numerical simulation of the characteristics, mechanism and evolution of the dissipative soliton pulse are carried out. In the error range, the numerical simulation results are basically consistent with the experimental results. Numerical simulation of pulse propagation under dispersion management is carried out. The evolution of dissipative solitons under different net dispersion in the cavity is studied. At the same time, the parameters of saturated absorber in numerical simulation are changed, and the corresponding variation of dissipative soliton characteristics is studied. Finally, the band-pass filter is added to the system, and the bandwidth of the band-pass filter is changed to study the influence of band-pass filter on the corresponding characteristics of dissipative soliton. The formation mechanism of stable dark solitons and light and dark solitons in fully positive dispersion fiber lasers is numerically simulated. By changing the parameters of saturated absorbers and the length of single-mode optical fibers, the effects of saturated absorbers and net dispersion values in cavity on dark soliton characteristics are studied.
【学位授予单位】：江西师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN248

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