Research On Pulsed Fiber Lasers Based On Graphdiyne And Its Analogues

Since the invention of the first laser in 1960,the laser has quickly attracted people's attention due to its excellent performance,and has become the world's best light source.Lasers,along with semiconductors,computers,and atomic energy,are regarded as four major modern inventions in the 20th century,which have had a profound impact on human society.At present,laser technology has penetrated into various disciplines.It renewed these fields and greatly promoted the technological progress and development.Among various types of lasers,fiber lasers stand out due to a series of advantages such as compact structure,high integration,low insertion loss,and low cost.They have become the mainstream light source in the traditional industrial field and the high-quality light source for dense wavelength division multiplexing systems.So they have important applications in the manufacturing and communication fields.Along with the development of lasers,various laser technologies aimed at improving laser performance are also developing simultaneously.Among them,in order to meet the requirements for extremely narrow pulse width in precision ranging,transient imaging,lidar,and high-resolution spectroscopy,people have developed Q-switching and mode-locking technology to obtain pulsed lasers,which provide an important means for various disciplines to explore the microscopic world.Among the various methods of obtaining Q-switched and mode-locked pulses,optical saturable absorbers is most widely used.Among different kinds of saturable absorbers,the new carbon allotrope graphdiyne has become an ideal material due to its small bandgap,excellent semiconductor performance,and high thermal stability.In this article,we used graphdiyne and metalloporphyrin graphdiyne analogs as saturable absorption devices to obtain erbium-doped pulsed fiber lasers in the 1.5?m communication area,and realized different types of pulse output.This work opens a path for the application of graphdiyne and its analogues in the field of ultrafast photonics.This thesis consists of six chapters in total,and the main content of each chapter is as follows:Chapter 1 is the introduction,which mainly introduces the types of lasers,and the characteristics of solid-state lasers and fiber lasers.We briefly review the history of fiber lasers,and explain the principles of Q-switching and mode-locking technology.Besides,we analyze the development status of two-dimensional saturable absorbers at home and abroad.In chapter 2,we first summarized the research progress of graphdiyne,briefly introduced the structure of graphdiyne and characterized it in various ways.Then,we prepared graphdiyne saturable absorber based on tapered fiber structure.After that,the nonlinear absorption characteristics of graphdiyne saturable absorber was measured by a double-balanced detection system built by the laboratory.In chapter 3,the application of graphdiyne in passively mode-locked fiber lasers is explored.We integrated the graphdiyne saturable absorber into the ring resonator,and obtained the traditional soliton mode-locked pulse in the 1.5?m for the first time,and the single pulse width reached 734fs.After that,by changing the cavity length and the parameters of the tapered fiber,we obtained the harmonic bound state pulse on the basis of the fundamental traditional soliton.In Chapters 4 and 5,we discussed the application of manganese porphyrin graphdiyne analogs in erbium-doped fiber lasers.We have prepared two kinds of saturable absorbers and measured their nonlinear absorption respectively.Based on the jumper sandwich structure,we have obtained Q-switched pulse output.Based on the tapered fiber structure,we have obtained a variety of mode-locked pulse outputs,including fundamental frequency traditional soliton output,pulse cluster,soliton rain and quasi-rectangular wave output.In Chapter 6,we summarized the main work of this article,discussed the current problems,and looked forward to the work that needs to be improved in the future.