PREPARATION OF PASSIVE OPTICAL ATTEMUATOR AND OPTICAL SIGNALTRANSMISSION SYSTEM

PROBLEM TO BE SOLVED: To provide a passive optical signal attenuation element insertable to any point of an optical waveguide so as to generate a required loss amount and usable so as to provide a termination practically without reflection for an optical fiber. SOLUTION: This passive optical attenuator is provided with a part of the waveguide provided with a core 22 and a clad 24. The waveguide part receives the radiation of light and absorbs at least 0.2dB/m of the light radiation along the length. The waveguide is constituted so as to practically uniformly perform the absorption of about 1-1000dB/m along the length. Attenuation is kept fixed with optical power smaller than 100mW. The waveguide is formed from a fused silica fiber and the fused silica fiber is provided with an area doped by metal ion selected from a class composed of Fe, Ni, Co, Cr, Cu, Ti, Mn and V in a valid density for providing a prescribed absorption degree in a prescribed wavelength.