Research On Erbium-Ytterbium Co-doped Fiber Grating Random Laser

Fiber random lasers do not require a fixed optical resonator,and have the advantages of simple structure,low phase noise,weak coherence,high laser conversion efficiency,and good stability.It is expected to be obtained in the fields of laser processing,laser weapons,optical imaging,optical measurement,etc.application.Conventional fiber random lasers use Rayleigh scattering in fibers as feedback,and often require relatively long single-mode fibers to obtain enough feedback.However,long-distance fibers also bring losses,resulting in a reduction in the conversion efficiency of fiber random lasers.And the pumping threshold increase.In addition,the stability of its laser output needs to be improved.In view of the above problems,this paper studies the erbium-ytterbium co-doped fiber grating random laser,which achieves wavelength tuning and stable laser output.1.A random multi-phase shifted fiber grating written on a 57 mm erbium-ytterbium co-doped fiber was designed and prepared by the phase shift mask method.The total length of the grating was 25 mm,and 20 phase shift points with random phase shifts were introduced at equal intervals.The average reflectivity of the engraved multi-phase shift grating reaches 28 d B,the 3d B bandwidth is less than1 nm,and the spectral stop band contains multiple transmission windows.2.Using the prepared random multi-phase shift grating to build a random grating fiber laser based on erbium and ytterbium co-doped fiber,and using the pump light side pumping random grating fiber laser to achieve the tuning method of controlling the laser output mode.The experiment proves that the output mode of this type of random fiber laser can be controlled by changing the side pumping position and pump power,and the stability of the random fiber laser can also be greatly improved by this tuning method.