Simulation Study On Thermal Effect Of Single-Ended Bonded Laser Crystals

Semiconductor laser diode(LD)-pumped solid-state lasers have played an indispensable role in various fields of modern society since the invention of lasers.Laser technology has also embarked on a path of rapid development with the deepening of research work.Solid-state lasers can be classified into a variety of lasers depending on materials and properties.Among them,chip-like and rod-shaped doped crystals are used as gain media.Compared with conventional lasers,they have small volume,high beam quality,large power per unit volume,high light conversion rate and other advantages.In practical applications,such lasers play an important role in the fields of optical fiber communication,space communication,medical equipment,and military.The thermal effect inside the laser crystal is one of the key constraints for the solid laser to obtain high output power and good beam quality.As the pump power of the solid laser increases,the effect of the crystal thermal effect becomes more serious.By bonding the undoped crystal on the doped crystal end face,the bonded crystal can effectively reduce the laser crystal center temperature,improve the internal temperature distribution of the crystal,and reduce the negative effect of the thermal effect on the laser.Based on the thermal effect theory,the simulation model of YVO4/Nd:YVO4 and GdVO4/Nd:GdVO4 bonded crystals in stable operation was established.The influence of external conditions and the shape of bonded crystals on thermal effects was studied by data and graph analysis.The erbium-doped solid-state laser with better thermal performance gives the experimental basis and optimization direction.This article mainly explains through the following aspects:(1)The development of solid-state lasers and their advantages are briefly introduced.The performances of common laser crystals and corresponding lasers are introduced.The research status of laser crystal thermal effect suppression at home and abroad is given.The laser gain crystals of several erbium-doped media are described in detail.The energy level principle and physical properties are introduced to the generation and function of bonded crystals.(2)Explain the basic principle of laser generation,and theoretically deduct and introduce the theory of rate equation and the broadening effect of line spectrum.The reasons for the thermal effect of the crystal are analyzed,and several aspects are introduced to how to reduce the thermal effect of the crystal.(3)Based on the crystal thermal effect theory and geometric structure,the thermal steady state simulation model of bonded crystal is given.The internal temperature distribution of the bonded crystal is given by the finite element analysis software,and the external conditions of the bonded crystal,including the pump power,The relationship between the temperature control temperature and the thermal conductivity of the contact surface was studied with the temperature of the bonded crystal center,and the simulation results were qualitatively verified by experiments.(4)Based on the theoretical and simulation models,the effects of the length of the bonded crystal itself and the size of the crystal cross section on the thermal effect under the given conditions are discussed,and the deformation and heat of the bonded crystal are obtained by temperature-mechanical coupling.Stress distribution and relationship between bonded crystal length and cross-sectional size.