| 摘要 |
PURPOSE:To produce the title distributed-refractive index type glass rod by dipping a glass rod in the molten salt contg. the ion having a higher refractive index than the metal ion contained in the glass and the ion having a lower refractive index than the metal ion, and exchanging the ions. CONSTITUTION:The glass rod contg. the ion-exchangeable alkali metal ion such as Na<+>, K<+>, and Li<+> is dipped in the molten salt of the nitrate, sulfate, chloride, etc., contg. an Ag<+> or Tl<+> ion capable of rapidly diffusing in the glass and having a higher refractive index than the alkali metal ion and the bivalent metal ion such as Sr<2+> and Pb<2+> or Mg<2+>, Ca<2+>, Ba<2+>, Cd<2+>, and Zn<2+> having the lower refractive index and lower diffusion and migration rate than the above-mentioned ion. The ions such as Na<+> in the glass rod are exchanged for the above-mentioned two kinds of ions, and a distributed-refractive index type glass rod having the refractive indexes high at the central part and decreasing toward the peripheral part can be obtained as an optical fiber base material.
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