The Absorption Property Of Ytterbium-doped Fiber On Short Wavelength Laser

Compared with the direct semiconductor pump,tandem pump configuration has obvious advantages in the realization of high-power fiber laser due to its high brightness,low quantum loss,etc.However,the absorption coefficient of ytterbium-doped fiber for short-wavelength laser(1000-1030nm)is low,which is one of the main factors that restrict the wide application of the tandem-pumping scheme in high power fiber laser.Therefore,in this paper,based on Yb-doped fiber amplifier,the theoretical and experimental studies on the feasibility of improving the absorption efficiency for short-wavelength laser are carried out.The main contents of this paper include the following aspects:The current research status and main problems of Yb-doped fiber laser and tandem pumping technology are introduced.The various schemes proposed by researchers to improve the pump absorption efficiency are discussed.The feasibility and deficiency of these schemes in the high power tandem-pumping system are analyzed.The effects of parameters of the laser amplifier on the pump absorption efficiency are systematically studied.The variation of pump laser absorption efficiency with the seed laser power is studied by simulation and experiment.The effects of 976 nm and 1018 nm dual-wavelength pump on improving the pump absorption efficiency are analyzed.The pump absorption efficiency with different pump distribution are experimentally and theoretically studied.A high-power high-brightness 1018 nm pump source is fabricated.Based on this pump source,the effects of pump brightness on the absorption efficiency are studied experimentally.The influence of temperature on the absorption of ytterbium-doped fiber is discussed.Taking 15/130?m Ytterbium-doped fiber as the research object,the reason why the coiling shape of the fiber affects the pump absorption efficiency is experimentally investigated.The change of the pump absorption efficiency of 30/250?m fiber under different bending radius is systematically studied.The change trend of pump absorption efficiency under the combined effect of optical fiber background loss,high-order mode loss,core mode field changing and seed laser power is analyzed.The influence of the change of the mode field on the pump absorption is discussed.