Research On The 0.9 ?m Single-frequency Fiber Laser And Its Frequency Doubling

The 0.9 ?m band single-frequency laser has the characteristics of narrow linewidth and low noise,which makes it widely used in the fields of remote sensing,spectroscopy and atomic cooling,and has attracted great attention.It can be used as high brightness and low-noise pump sources for Nd3+-,Yb3+-and Er3+-doped lasers,and can generate visible and deep UV laser through nonlinear frequency conversion.However,the properties,such as noise and linewidth of these laser sources,limit their application in many fields which need narrow-linewidth and low-noise single-frequency lasers.In this thesis,the realization of 0.9 ?m band high-performance single-frequency lasers were studied,which were 978 nm low-noise narrow-linewidth single-frequency fiber laser,and 935 nm single-frequency laser obtained by frequency doubling of 1870 nm high power single-frequency fiber laser.The specific research contents and main achievements are as follows:(1)A 978 nm DBR short cavity single-frequency fiber laser resonator was studied.The single-frequency fiber laser with a power of 30 m W,a signal to noise ratio(SNR)of more than 60 d B and a laser linewidth of 6.24 k Hz was realized.The conversion efficiency was 17.3%.Based on the seed source of 978 nm single frequency fiber laser,the structure of power amplifier and noise suppression device composed of ytterbium doped fiber amplifier(YDFA)and semiconductor optical amplifier(SOA)was adopted to realize the intensity noise suppression in the frequency range of 0.1-20 MHz,and the suppression was more than 15 d B.(2)A 1870 nm DBR short cavity single-frequency fiber laser resonator was studied,and the single-frequency fiber laser with 13.4 m W power and SNR > 59 d B was realized.Based on the above seed source and two-stage thulium-doped fiber amplifiers,the experimental study of its power amplification was carried out.The single-frequency fiber laser with power of 10.14 W and SNR of more than 48 d B was realized,and its optical conversion efficiency was 19.8%.Using 1870 nm high-power single-frequency fiber laser(fundamental laser)and periodically poled lithium niobium(PPLN)crystal,frequency doubling experiment in external cavity was carried out.The single frequency laser with power of 156 m W and wavelength of 935.3 nm was realized,and the conversion efficiency was 4.8%.(3)Using 978 nm low-noise single-frequency fiber laser and the PPLN crystal,SHG frequency doubling experiment in external cavity was carried out.The all-fiber,low-noise blue light single-frequency laser with power of 4 m W was obtained,and its conversion efficiency is 5.59%.