Study On The Fabrication And Properties Of The COP/Ag Leaky Type Of Hollow Waveguide For CO₂ Laser Transmission

The bright prospect of applications for COa laser in medical laser surgery, materials processing, etc, is presently darkened by the lack of efficient delivery tools. Whereas, there is an urgent need of manufacturing waveguides with excellent performances. This work focus on the design and fabrication of the Ag/COP(cyclic olefin polymer) leaky type of hollow waveguide.Dielectric/metal hollow waveguide theoretically exhibits a loss lower than that of the metal hollow fiber. Therefore the former is chosen in this research work.In the experiment silica glass tubes with diameters 1 mm were chosen as the basic fibers. Both the dielectric layer and metal film were internally deposited on the fiber. It is found that Ag is able to engender the highest IR reflectivity among the metal materials, So Ag is ascertained as the metal layer material of the hollow waveguide, COP was used in this work as the dielectric material. Based on countless calculations, optimum thickness for the deposited films were obtained, namely, 0.2 //m for Ag layer and 1.4 fan for the COP layer.In this work, the aspects those impose influences on the performances of the Ag films such as the pretreatment of the basic tubes, the concentrations of the reactants, the reaction time were investigated. Apart fffm this, great attention^ was given to the study on the parameters in the process of Ag deposition in which low concentration and high temperature, or high concentration and low temperature was alternatively adopted. The mechanism and the result of the sensitization via SnCb solution were profoundly investigated.On the base-of the careful study on the pretreatment process of the silica glass tubes, proper processing parameters were obtained. Reasonable process of depositing COP films was finally ascertained based on the investigations of the various factors such as the concentration of the coating solution, the withdraw used in the heat treatment of the COP film, and so on.It was confirmed that the loss of the COP/Ag leaky type of hollowwaveguide is lower than that of the simple Ag fiber. For example, in terms of the attenuation for straight delivery, the former is less than 1.45 dB/m while the latter is 1.6 dB/m. Accordingly, as far as the bent loss is concerned the Ag fiber is highly above the COP/Ag fiber, especially when the carve angle is increased. However, the above results follow the transmission laws of the dielectric/metal leaky type of hollow waveguide well. Moreover, it was found that the COP/Ag fiber can stably transmit COa laser for more than 35 minutes although the output laser reach as highly as 55 w. Therefore, the COP/Ag leaky type of hollow waveguide fabricated in this work will be a good candidate for COa laser delivery in medical surgery as well as material processing.