Study On The Fabrication Process And Transmission Characteristics Of AgI / Ag Hollow Fiber With Low Loss And Low Loss

Hollow fiber is one of the most promising media for laser power delivery in the infrared (IR) regions. Depending on its inner-coating materials and structure, the hollow fibers can be categorized into two kinds:the leaky guide and ATR guide. Up to now, the one with Ag as the metal film and AgI as the dielectric film is the most actively studied hollow fiber. It has found applications in medical and industrial fields owing to its high power capability, excellent flexibility, and low-loss property.The research of AgI/Ag hollow fiber has been deepening since the late1980s, and the AgI/Ag fiber with high performance in mid-and far-IR region have been prepared and fabricated successfully. Especially the hollow fiber tailored at the wavelength of10.6μm has been commercially available because of its excellent transmission performance. Limited by the control of the thickness and surface roughness of AgI film, the low loss in the near-infrared regions for AgI/Ag hollow fiber is rarely reported. In this thesis, the history, development, and transmission principle of AgI/Ag hollow fiber are reviewed, and the fabrication techniques of low-loss near-infrared AgI/Ag hollow fiber are studied. To coat a smooth AgI film, ethanol is adopted as the solvent of iodine and the iodination process is carried out in low temperatures. The process of AgI film formation is slowed down due to the new solvent and the low temperature. Film uniformity is also improved for high flow-rate of the iodine solution by using a vacuum pump. Low-loss property in the near-IR region for the AgI/Ag hollow fiber is firstly attained. The measured transmission loss is0.8dB/m for the1.064μm DPSS laser system. By analyzing the experimental results, fabrication parameters, including iodine concentration, iodination time, and reaction temperature are discussed in detail. The transmission and bending loss properties of the Agl/Ag hollow fibers with various inner diameters are also evaluated. With low transmission loss and small additional bending loss, the AgI/Ag hollow fiber shows great potentiality to deliver high power or ultra-short laser pulse in the near-infrared regions.