| 摘要 |
PURPOSE:To increase a core/core diameter ratio by forming a core part of a rare earth-added fluoride glass having an optical amplifying function and a clad part of oxide glass or fluorine oxide glass having no absorption at specific wavelengths. CONSTITUTION:Raw materials to constitute the oxide glass of an SiO2-RO-M2O system (R is an alkaline earth metal, M is an alkali metal), etc., or the fluorine oxide glass of a P2O5-AlF3-RF2-MF system, etc., are melted by heating and are cast into a casting mold for the clad part. On the other hand, a rare earth raw material, such as Nd, is added and mixed at several thousands ppm or below to and with the fluorine oxide glass raw material of an AlF3-RF2-MF system, etc., and the mixture is melted by heating. The melt of glass melt for the core is then poured into a through hole of the prescribed bore of the cooled and solidified clad part and is slowly cooled to form a disk-shaped glass. This glass is extrusion molded, by which the preform for the 1.3mum band optical amplifying fiber formed of the core part having the optical amplifying function at 1.3mum and the clad part having no absorption at the excitation wavelengths and amplifying wavelengths in the 1.3mum optical amplifier is obtd. |
