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Research On Key Technologies Of 1.5 ?m Narrow Linewidth Single Frequency Fiber Amplifier

Posted on:2022-01-13Degree:MasterType:Thesis
Country:ChinaCandidate:L J ZhangFull Text:PDF
GTID:2518306557964919Subject:Optical Engineering
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Single frequency narrow linewidth fiber laser has the advantages of narrow output spectral line width(up to 10-9 nm),compact structure,low frequency noise and ultra-high coherence,so it is widely used in a variety of social fields and scientific research,such as lidar and gravitational wave detection,in coherent detection applications and also used in frequency conversion and beam combination.In recent years,domestic researchers have been very keen on the research of single frequency narrow linewidth fiber laser.In this paper,1.5?m narrow linewidth single frequency fiber amplifier system has been studied comprehensively.The output of single frequency fiber laser is realized by main oscillator power amplifier(MOPA).In this paper,12/130 polarization maintaining double clad erbium-ytterbium co-doped fiber is used as gain fiber,and two-stage double clad fiber amplifier and reverse off-peak940nm pumping technology are adopted,which reduces the gain by 1?m ASE emits and self-excited oscillation,uses high conversion efficiency reverse pumping scheme to reduce the gain fiber length,so as to suppress SBS effect.High power narrow linewidth single-mode polarization maintaining laser with 5 k Hz linewidth and 32.6 W single-mode output power is realized.The optical to optical conversion efficiency is as high as 40%.The linewidth broadening factor of cascaded fiber amplifier is 1.1,the spectral SNR degradation is 2.56 d B,and the RIN degradation is 1.62d BC/Hz@1MHz,PER>16.1d B and it has good beam quality after amplification.The characteristics of low noise and narrow linewidth are effectively maintained.The research results provide technical support for coherent lidar,gravitational wave detection and space optical communication.Based on the previous work,the research of on 1.5?m narrow linewidth single frequency fiber amplifier system combined with the needs of practical application,this paper further expands the structure of the amplifier,and completes the research of 20W dual polarization amplifier.The 20W dual forward polarization amplifier is based on single frequency narrow line optical seed modulation,main oscillation power amplification and polarization incoherent beam combining the plan is as follows:The fiber amplifier uses a distributed feedback single frequency semiconductor laser as the seed source and adopts a two-way fiber amplifier structure.The two-way polarized light is amplified to 11W through the fiber amplifier,and then the high-quality and stable laser output is achieved through the polarization incoherent beam combining technology.When the pump power is 55.3 W,the center wavelength of the output laser is 1549.913 nm,and the linewidth of 20 d B is 117 k Hz.When the pump power is 55.3 W,the spectral signal-to-noise ratio(SNR)is more than 60 d B.When the maximum output power of the system is 19.93 W,the reverse power measured at the monitoring end is only 1.85 n W,and the optical to optical conversion efficiency is 34.9%.At the same time,based on the mature system scheme,on the basis of the original work,the structure,electric control system and thermal design of laser are optimized synchronously.Advanced engineering technology is adopted to improve the stability,reliability and integration of the laser system,and the test of its performance is completed.
Keywords/Search Tags:Fiber amplifier, erbium ytterbium co-doped, single frequency, narrow linewidth
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