Research Of Annular Pump Beam Based On End Pump Solid State Lasers

Hollow beams have many unique physical properties and wide range of applications, so how to form them is becoming a research hot spot. In this thesis, we propose a method and device of forming annular pump light based on the circular pump light pumping the end pumped solid state laser and the output of high-order Laguerre-Gaussian beam, namely the hollow beam.The basic working principle of end pump solid state laser is introduced, including the pump source laser diode, the laser gain medium and the laser resonator. We put forward a method of using the axicon combination to produce the annular light. The formation of annular pump beam is analyzed, including the optical principle of different axicon combination and the match between annular pump light and laser mode. Specific theoretical simulation and experimental process and results are given.The solid pump light is coupling by fibers from LD source and then it is collimated by the lens. Annular pump light with adjustable size could be obtained by the shaping system consists of an axicon and a focal lens. Using the geometrical optics, the theoretical analysis and numerical simulation based on the software ZEMAX were given. The experimental results demonstrated that this method could be adopted to generate annular pump light. In experiment, the results showed that the power conversion efficiency could reach up to 64.5% under the condition that the lens and axicon were uncoated, so it meets the pump power requirement. During the research, the phenomenon of the invariant dark spot of the annular pump light was analyzed.The theoretical simulation and experiment both prove that this scheme is simple, efficient and low cost. It can realize the real-time tunable of the annular beam. It has important significance for the output of high-order laser mode in end pump solid state lasers.