Research On Thulium Doped Fiber Laser And Coherent Beam Combination

Emission spectra of Tm³⁺-doped fiber laser which contains two atmospheric windows and a strong water absorption peak covers from1.5μm to2.2μm. Because the wavelength is safe to man's eyes,it is being applied in many areas such as laser medicine,long-distance detective systems,laser radar,and military.Laser power is increasing from hundreds of watts to thousands of watts and now Tm³⁺-doped fiber laser is becoming the research focus of fiber lasers.Recently,much work about Tm³⁺-doped double clad fiber laser focuses on experiment research.It is urgent to make a deep research on mathematical model which is very important to carry out a further study about Tm³⁺-doped double clad fiber laser.This paper gets a series of useful conclusions by numerical simulation.On the other hand this paper includes the work related to coherent beam combination.Coherent beam combination is a method for achieving a high-power,high-brightness source.This paper makes a research about multi-core double-clad fiber laser and Michelson interferometer resonator.The results of this paper can gave some suggestions in design of high power and brightness Tm³⁺-doped fiber laser.The main contents in this paper are as follows:1.The characteristic of the energy level structure of thulium and the absorption spectrum are investigated.Three kinds of pump scheme of the Tm-doped fiber laser are discussed in detail.Research on the common pump scheme ³H₆â†'³H₄ are carried out.We obtain the equation about the number of Thulium ions in ground state and excited states in fiber laser.2.About forward pump scheme ³H₆â†'³H₄ using 790nm laser resource,we design simulation program which draw some conclusions about the relationship between laser properties and pump power,fiber length,doped concentration of Thulium ions and loss.3.We derive the coherent beam intensity of the far-field about multi-core double-clad fiber laser by applying diffraction theory.Simulation program is designed and we obtain some conclusions about the relationship between the intensity of the tar-field and multi-core number,distance of adjacent core axes,diameter of core and wave length.4.Through the study of the coherent beam combination principle by applying all-fiber Michelson interferometer resonator,we discuss the spectral response fun.By designing simulation program,we analyze the effects of different branch-arms number, adjacent length difference,and reflectivity of public resonator,and get some useful conclusions.