Research On 1120nm Yb-Doped Fiber Laser

Due to the advantages such as high efficiency,excellent beam quality as well as simple and compact structure,compared with solid-state lasers,optical fiber lasers have been attracting great research interest for decades,and have been widely used in many fields such as industry,medical treatment,scientific research and national defense.High power fiber lasers operating at 1120 nm have attracted worldwide attention for various applications which for example,includes pumping Raman fiber amplifier and then frequency doubling to yellow laser for laser guide star generation,frequency conversion and so on.Compared to continuous wave lasers,high peak power pulsed fiber lasers are easier and more economic to implement the applications mentioned above with a much lower average power.This paper mainly focuses on the theoretical and experimental research of 1120 nm Ytterbium doped?Yb-doped?fiber laser.The main work comsists of two parts:continuous wave operation and pulse operation Yb-doped fiber lasers at 1120 nm.The principal contents include:?1?The continuous wave high power 1120 nm Yb-doped fiber laser has been fully detailed.Firstly,Yb-doped fiber laser with double-cladding polarization-maintaining fiber and polarization-maintaining fiber Bragg gratings is used to construct the all-polarization-maintaining line cavity.Linear polarization,narrow line-width and high-power Yb-doped fiber laser with 1120 nm is realized by using cladding pumping technology.The system operating at a center wavelength of 1118.7 nm with a linewidth of 0.08 nm.Laser gain greater than 60 dB.When the injected pump power is 23.09 W,the laser output power is 14.67 W,corresponding to the optical-to-optical conversion efficiency of 63.5%.The polarization extinction ratio is 19.8 dB on average.In another research work,the FBGs in the above experiment is axis-parallelly fused.Thus a dual-wavelength switchable fiber laser operating at 1120 nm is implemented.In the dual-wavelength operation,the two oscillating wavelengths are 1118.912 and 1119.152 nm,respectively with a wavelength interval of 0.24nm.The signal-to-noise ratio?SNR?is 35 dB.When the LD pump power is 24 W,the maximum output power is 14.67 W,corresponding to an optical-to-optical efficiency of61.1%.In the single wavelength operation,the two separate wavelengths are 1118.912 nm and 1119.152 nm,and the average polarization extinction ratio?PER?is 20.3 dB and 19.9dB,respectively.This high-power dual-wavelength fiber laser with a spacing of 0.24 nm can be used as a source for microwave generation.?2?Passively Q-switched Yb-doped fiber lasers operating at 1120 nm with simple linear cavity configuration are demonstrated.?1?Study on pulse Yb-doped fiber laser at 1120 nm based on the saturable absorption of silicene.Firstly,Silicene saturated absorbers?Silicene-SA?is prepared.Then passive Q-switched Yb-doped fiber laser are respectively constructed.When the pumping power is 216 mW,the obtained shortest pulse width is 1.87?s with the output power of 1.71 mW.The oscillating central wavelength is 1120.36 nm with a 3 dB bandwidth as narrow as 0.08 nm.The experimental results present that Silicene possesses excellent saturated absorption characteristics and can be applied to achieve short pulse operation.?2?Based on the saturable absorption characteristics of molybdenum disulfide?MoS₂?,the Q-switched operation of a linear cavity Yb-doped 1120 nm fiber laser is realized.MoS₂ nanosheets are prepared and the optical properties of the materials are tested.Based on the MoS₂-SA,the passive Q-switched Yb-doped fiber laser at the wavelength of 1120 nm is implemented.When the pump power is 300 mW,the shortest pulse duration is 1.71?s with an average output power is 2.08 mW.This is the first time that MoS₂-SA has been applied to a linear cavity Yb-doped 1120 nm fiber laser to obtain Q-switched operation.The prepared MoS₂-SA possesses ideal saturation absorption character-ristics.Moreover,the system has an excellent operational stability.