In view of the present status of low loss and ultra—low loss fiber which been gradually applied to communication system

this paper reviews the characteristics of low loss andultra—low loss optical fiber

investigated their appUcation and prospects.This paper explored and proposed link design value as an improved approach to assess attenuation.Actual application cases of low loss fiber and ultra—low loss fiber and associatedcost analysis have been presented.With the existing standards and actual data from manufacturers

the paper puts forward the suggestions for modification of attenuation specification.