| 摘要 |
PURPOSE:To obtain an optical fixed attenuator capable of obtaining a desired extent of attenuation with a good reproducibility by heating and drawing an optical fiber having a light absorbing layer in the clad part to obtain the desired extent of attenuation. CONSTITUTION:The optical fiber having a light absorbing layer 2 in a clad part 1 is heated and drawn to obtain a desired extent of attenuation. Since most of energy of signal light is generally propagated in a core part 3 of the optical fiber in optical fiber transmission, the light absorbing layer scarecely has an influence upon the extent of attenuation though the optical fiber has the light absorbing layer in the clad part 1. However, when the optical fiber has the diameter reduced similarly by heating and drawing, a part of energy of signal light is absorbed to realize the optical fixed attenuator because energy of signal light is propagated in not only the core part 3 but also the clad part 1. Since the extent of light absorption is changed in accordance with the shape and the length of a heated and drawn part 4, the extent of attenuation is easily adjusted in accordance with the degree of heating and drawing. Thus, the optical fixed attenuator is realized which can obtain a desired extent of attenuation with a good reproducibility. |
