Specialty Optical Fibers Handbook

The dual coating is used to protect the fiber and to reduce the stress at the

fiber when external force exists to the fiber due to cabling or spooling. Yang [62]

describes the impact of coating properties on microbending loss: Microbending

losses decrease with increasing thickness, Young’s modulus, and Poisson’s

ratio of the primary coating. Similarly, changes in refractive index in the glass

fiber decrease with the increasing Young’s modulus and Poisson’s ratio of the

secondary coating.

Figure 2.18 shows a calculation of the stress at the fiber axis as a function of

primary modulus and secondary modulus following Yang’s derivation [62]. As the

modulus of the secondary coating increases, the stress decreases. However, as the

modulus of the primary