| 摘要 |
PURPOSE:To improve the strength of the optical fiber by heat-treating a part or the whole of the fluoride glass preform, fluoride glass rod and fluoride glass pipe in an F-contg. gas and then drawing the preform. CONSTITUTION:A fluoride glass rod having a core composition obtained by casting a molten glass and a fluoride glass tube having a clad composition are etched in a hydrochloric acid soln. of ZrOCl2, washed with water and then vacuum-dried. The glass rod and tube are heat-treated at 0-400 deg.C in the atmosphere of a gaseous mixture of one or >=2 kinds among HF, CF4, NF3, SF6, BF3, F2, etc. The atmosphere is then replaced by gaseous Ar, and the rod and tube are cooled to room temp. to obtain a preform. The preform is inserted into a glass tube in an N2 atmosphere, 'Teflon FEP(R)' is used as the coating material, and the preform is drawn to obtain a fluoride optical fiber having a low loss and high strength. |
