OPTICAL FIBER AND PLANAR WAVEGUIDE FOR ACHIEVING A SUBSTANTIALLY UNIFORM OPTICAL ATTENUATION

摘要

PURPOSE: An optical attenuator is provided, which includes an optical fiber having a core doped with a dopant absorbing a light in a fixed wavelength band, and the optical fiber and a planar waveguide are provided, which attenuate an optical signal constantly. CONSTITUTION: An optical fiber is for obtaining a constant optical attenuation and has a core layer(13) and a clad layer(12). The core layer is co-doped with at least more than one ion of the first metals whose absorption coefficient has a negative slope in a fixed wavelength band and at least more than one ion of the second metals whose absorption coefficient has a positive slope in the fixed wavelength band. The first metals are Fe, Cr, Mn and V. And the second metals are cobalt and nickel.