单掺铥固体激光器热效应研究进展与理论分析

Research progress and theoretical analysis of thermal effects of single thulium doped solid state lasers

随着中红外2μm波段固体激光器在工业、医学、军事和科学研究等领域中的不断扩展,其研究的重要性越来越明显。单掺铥固体激光器的输出波长恰好处于2μm附近,因此成为人们研究的热点方向,但单掺铥晶体由于发射截面小,上转换、重吸收效应严重等原因导致其热效应明显,严重影响了激光器的输出性能,使激光器的发展受到严重限制。因此研究激光晶体中的热效应对激光器性能的提升具有重要意义。本文综述了自研究热效应以来国内外基于各种基质的单掺铥固体激光器的热效应的研究成果,同时对固体激光器热透镜效应的热传导理论以及对热透镜效应的发生环境和形成条件有影响的因素进行阐述和分析。最后针对分析过程中所涉及的热功率密度,光强等参数进行讨论,为热透镜效应的热焦距计算和测量奠定了良好的理论基础。

With the continuous expansion of solid state lasers in the mid infrared 2μmband in the fields of industry,medicine,military and scientific research,the importance of their research is becoming more and more obvious.Single thulium doped solid state laser with output wavelength in the vicinity of 2μmhas become a hot direction of research.However,the thermal effect of single thulium doped crystal is obvious due to its small emission cross section,up conversion and serious re absorption effects,which seriously affects the output performance of the laser,and severely limits the development of lasers.Therefore,it is important to study the thermal effect in laser crystals for the improvement of laser performance.In this paper,the research results on the thermal effects of single thulium doped solid state lasers based on various substrates at home and abroad since the study of thermal effects are reviewed.At the same time,the heat conduction theory of the thermal lens effect of solid state lasers as well as the factors that have an influence on the occurrence environment and formation conditions of the thermal lens effect are explained and analyzed.Finally,the parameters involved in the analysis,such as thermal power density and optical intensity,are discussed to lay a good theoretical foundation for the calculation and measurement of the thermal focal length of the thermal lens effect.