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Study On High-average-power Pulsed Fiber Laser

Posted on:2013-01-28Degree:DoctorType:Dissertation
Country:ChinaCandidate:W D WuFull Text:PDF
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In1961, as the first laser was invented, the laser technology is developedrapidly. Types of lasers can be divided into different substances by the operationsmaterial, such as solid-state lasers, gas lasers and chemical laser. Fiber laser as a newtype of solid-state lasers, comparing with traditional solid lasers, fiber laser hasdistinguished superiority in efficiency, volume, beam quality, compactness and so on.Especially, the pulsed fiber laser is very important for the present and potentialapplication including medical treatments, scientific researches, military affairs,material processing and so on. At present, up to ten thousand watts of output power incontinuous-wave (CW) mode has been demonstrated in a single transverse mode.Dawson et al. made a study on the output power of fiber lasers, which showed themaximum output power of fiber lasers, which showed the maximum output power offiber lasers with the diffraction limit of36.6kW for wide bandwidth and1.86kW fornarrow bandwidth, respectively.The pulse fiber laser can achieve a higher peak powerlaser output, to make up for the many limitations of the CW fiber laser such as thelaser and the target for interaction, or nonlinear frequency conversion applications, itis an important research direction in the field of high power fiber laser technology. Inthis dissertation, we have done some theoretical and experimental study onhigh-power narrow linewidth pulsed fiber lasers and fiber laser frequency doublingtechnology.The first chapter is a brief introduces of Yb3+-doped double-clad fiber firstly. Weanalyze the three main methods which are getting the pulse fiber laser: themaster-oscillator power amplifier (MOPA), Q-switched and mode-locked techniques,and give some typical research results of the research institutes at home or abroad.Moreover introduce the latest progress of the nonlinear harmonic generation of fiberlaser technology and experimental results.The second chapter is study on the theoretical and experimental of Sm3+-dopedfiber as saturable absorber passive Q-switched fiber laser. Analysis of the basic theory of passively Q-switched laser firstly, and introduce the key technology andcomponents of all fiber lasers. We study on the Sm3+-doped fiber as saturableabsorber passive Q-switched fiber laser. Using three types of cavity, achieve theaverage power of2.3W, the center wavelength1064nm, the pulse width of450ns, arepetition rate of18kHz in single FBG cavity; the average power of2.26W, the centerwavelength1080nm, the pulse width of648ns and a repetition rate of310kHz in threeFBGs cavity; the average power of1.93W, the center wavelength1080nm, the pulsewidth of816ns, a repetition rate of212kHz in two FBGs cavity.The third chapter, WE firstly introduces the key technologies of high averagepower pulsed fiber laser amplifier. Using the gain switch LD as the seed source,through the Yb-doped fiber MOPA structure, carried out the average power of101W,the pulse width of16.7ns, the repetition rate of51kHz pulse laser output. Anall-fiber-based master oscillator power amplifier picoseconds Yb3+-doped fiber laserwith average power of102W and the center wavelength of1064nm, the spectral linewidth of0.1nm, the pulse width of76ps. And using of picosecond pulsed laser fineprocessing and industrial cutting experiments to prove its strong application.The fourth chapter, we study on the pulse fiber laser frequency doublingtechnology in the theoretical and experimental. We analyze the basic theory ofnonlinear frequency conversion, phase matching method, and the laser spectrallinewidth on the SHG efficiency. A master oscillator power amplifier (MOPA) systemwhich can provide narrow linewidth pulsed laser was constructed by an all fiberQ-switched laser used as seed laser. The system can generates up to maximum15Waverage power of amplified radiation with narrow linewidth and linear polarization at1080nm. Based on the pulsed amplified radiation with narrow linewidth,3.5W greenlaser was obtained by single-pass frequency doubling using non-critical phasematching KTP crystal.
Keywords/Search Tags:pulsed fiber laser, passively Q switched, Sm3+-doped fiber, pulsed fiber amplifier, narrow-linewidth, frequency doubling
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