The Study On Design Of High Power Planar Waveguide Amplifier Laser System And Investigation Of Mechanism

High efficiency and stable the laser diode pumped solid-state lasers with compact structure,small volume and high beam quality have been more and more widely applied in the field like medical treatment,scientific research,industrial processing and defense,etc.Diode pumped planar waveguide(PWG)all-solid-state lasers consisted of the high-refractive-index core layer and the surrounding low-refractive-index clad,belonging to the high aspect ratio of the sandwich structure,owning a high absorption efficiency of the pump,a large heat dissipation surface area,a thin gain layer thickness,and a smaller nonlinear effect of the crystal material than the conventional glass fiber,is one of the major development directions of high-energy all-solid-state lasers in the next few years.Therefore,the development of high-power laser system based on PWGs,will have a huge market application and national defense strategy value.A continuous laser amplification system based on Yb: YAG PWG gain medium was designed.Firstly,a large-mode-area(PWG)device with double-clad structure and capability of realizing the fundamental-mode output was designed as a gain medium for solid-state laser amplifier.This provided the basis for the design of a PWG laser amplification system with high output power and high beam quality.Secondly,some characteristic parameters of double-layer PWG lasers was mainly analyzed,such as: single-mode output condition of ordinary double-clad PWGs,single mode output condition of double clad LMA PWGs in the case of gain competition,the relationship between the absorption efficiency and the thickness of the inner cladding under the cladding pump,thermal effect and the maximum allowable pump power restricted by this,etc.Finally,the theoretical output characteristics including small signal gain,large signal gain characteristic,maximum output powers and amplification efficiency were studied.The results show that by controlling the difference between the refractive index of the PWG core layer and the cladding small enough,the incident fundamental transverse seed beams along the waveguide axis can realize both the energy amplification and the single transverse mode output.At the same time,by controlling the uniform transverse temperature distribution of PWG in large surface cooling,the degradation of the beam quality in the non-waveguide axis direction can be reduced,and so the high beam quality output can be obtained.According to the design results,the continuous laser amplification system based on the designed Yb:YAG PWG theoretically can support the laser output of an order of kW.