DMH波导的制作及其特性研究

【作者】 张红瑞；

【导师】 梁二军； 沈书泊；

【作者基本信息】 郑州大学 ， 凝聚态物理， 2000， 硕士

【摘要】 介质加强的金属中空波导（dielectric-coated metallichollow waveguide，以下简称DMH波导）是目前传输大功率CO₂激光的一种具有很大发展潜力的途径，然而由于DMH波导的制作工艺和耦合条件等因素所造成的在传输过程中的损耗，在很大程度上影响了DMH波导潜力的发挥。 本文针对上述影响波导损耗的各种因素作了研究，主要得出了下面结果。 1、根据DMH波导中的模式理论及相关的损耗系数，得出DMH波导的损耗与波导芯半径a的三次方成反比，波导的弯曲损耗与曲率半径R成反比，并且当介质层材料的折射率在（?）附近时，波导的损耗最小，另外，波导损耗还与介质层的厚度及内表面的粗糙度有一定的关系； 2、针对波导的传输阈值，本文得出DMH波导的表面温度随波导长度呈振荡变化，在波导两端温度最高，并计算出用水冷却时能有效地提高波导的传输能力，并依此而设计出了波导的冷却装置； 3、本文采用液相沉积的方法制作出了AgI/Ag结构的DMH波导，并在实验中逐步改进了制作工艺。在此基础上提出了一种新颖而且实用的测量厚度方法(测量误差〈2％〉； 4、DMH波导入射光的耦合条件在很大程度上决定了波导的损耗，本文得出波导的耦合条件可以用ω/a（ω为入射光束腰半径，a为波导内芯半径）来描述，得出波导损耗最小时的耦合条件并非HE₁₁模的最佳耦合条件ω/a≈0.64，而是由入射光和波导的结构综合决定。在本实验中使用了余弦光束CO₂激光器作光源来测量波导的传输特性。更多还原

【Abstract】 abstractProperties of a dieiectric-coated metaIilc ho jiow waveguide(DMHwaveguide) for direCting high power CO2 laser beams is studied. Thefactors influencing the power Iosses during propagation of the laser beamin the DMH waveguide are anaIyzed. A AgI-coated Ag DMH waveguide isprepared by a chemical reduCtion method.The foIIowing resuIts are obtained.1.According tO the pattern and the reIavent attenuation co6fficent Ofthe Iaser beam in the DMH waveguide we got a condusion that the powerloss in DMH waveguides is in inverse proportion to the cub6 of thewaveguide’s radius and tO the winding curvature radius. The Ioss wiIl bethe IeaSt when the retheCtion index of the dieIeCtric Iayer approaChes fi.ln addition, the power Ioss in the waveguide depends on the thiCkness ofthe dieleCtric Iayer and the index of the roughness of the inner sudece,2.In the light of the waveguide’s transmission threshoId value, we getthat the waveguide’s surf8ce temperature osdIIates with it’s Iength. At thetwO ends Of the waveguide, the temperature is the highest. Nso wecalcu:ated that using water cooling, ihe tr8nsmission threshoId vaIue couldbe theCtiveIy improved. A cooling device for the wav6guide is’desiged;3Using Iiquid-Phase dePOsiting teChnology we develoPed a methodfOr making AgI-coat6d Ag hoIlow waveguide, optimized the makingprocedure. A new and praCtical method for measuring the thiCkness Of thecladding materiaI during the making process is giveni4.The coupIing coedcient of the Iight into DMH waveguide, whiCh isdedned as to l8(co is the incident light’s waist radius and a is thewaveguide’s core radius) influences the POwer Ioss greatIy It is concIudedthat the least power loss does not occur at the optimum couplingcoefficient for HE11 mode-- to lase0.64 whereas it is synthesiticalIy decidedby the pattern of the inddent Iight and the form of the waveguide. A newlight beam--CO2 laser is used to test the property of the waveguide.更多还原