Design Of Fresnel Lens Concentrating Solar Pump Fiber Laser

Solar energy is the most ideal alternative energy source for mankind in the future,and countries attach great importance to the development and utilization of solar energy in the development of new energy.With the support of renewable energy in the 13 th Five-Year Plan,China will continue to expand solar energy in the future.The scale of utilization is in line with the general trend of global energy transformation.Solarpumped fiber lasers are currently a promising solar-pumped solid-state laser that can achieve high energy conversion efficiency and high power laser output.Moreover,because of its flexible laser output direction,it is easy to achieve power cascade doubling,convenient cooling,good beam quality,high power density and other advantages and is favored by researchers.Based on the analysis of existing solar light guiding technology and solar pump laser,this paper designs the solar pump laser that is concentrated by Fresnel lens.In this paper,based on the Fresnel lens-cone-fiber-converging light guiding technology,by adjusting the relative position of the Fresnel lens and the cone,the size of the receiving end and the output end of the cone and the length of the cone and the incident deviation of sunlight are changed.Angle and other parameters,using the TracePro software to optically simulate the converging light guide module.The erbiumdoped double-clad fiber was used as the gain medium.The MATLAB software was used to simulate the rate equation under steady-state conditions.The wavelength of the pump light,the doping concentration of the gain fiber,and the size and length of the fiber were analyzed.The influence provides a theoretical basis for the design of solarpumped double-clad erbium-doped fiber lasers.Based on the analysis,the Fresnel lens has good concentrating effect and high optical efficiency,but the spot size radius is larger than that of the fiber,and the direct coupling efficiency is low.On the basis of the Fresnel lens as the first-stage concentrating system,the cone rod is added as the secondary concentrating system,and the optical flux is obviously improved after the fiber is placed at the output end of the cone.In addition,the position of the receiving end of the taper bar is slightly deviated from the focus position,which is more conducive to concentrating,and can be adjusted according to the actual situation in the direction of the main axis of the system to determine the optimal position and optimize the effect of concentrating.At the same time,numerical analysis shows that in order to obtain a small pump threshold power,a pump beam with a large absorption cross section,a small core effective cross-sectional area and a long length gain fiber are required.