| 摘要 |
PURPOSE:To stabilize IR transmission by holding a specific relation between the number of periods of alternate multi-layered films in an intermediate part and the number of periods of alternate multi-layered films at an incident end and exit end. CONSTITUTION:This optical fiber is coated with the alternate multi-layered films in both the intermediate part and the incident and exit ends. These films are so formed that the number (n) of repetitions of the alternate multi-layered films at the incident and exit ends is larger than the number (m) of repetitions of the alternate multi-layered films in the intermediate part; i.e., n>m>0. One period of the alternate films are first coated on the fiber over the entire length thereof and furthermore, two periods of the alternate layers are coated only at the terminal parts. Then, the multi-layered film clad fiber consisting of 3 periods (n=3) in the terminal parts and 1 period (m=1) in the intermediate part. The alternate multi-layered films refer to combinations of thin films such as PbF2/Ge and PbF2/AgBr. Film thicknesses of respectively about 1-2mum are preferred in the case of PbF2/Ge. The fiber having the high stability of the optical transmission characteristic is thereby obtd. |
