Three major technologies to extend the life of optical cables

The optical fiber and cable industry has experienced more than 30 years of development and has now entered a peak period
of upgrading.
As a result, the topic of cable life has also attracted much attention
in the industry.
Because the external environment and internal quality of optical cables in the actual use process are quite different, the life problem is more complicated
.
At present, the industry has proposed three major technical points
that affect the life of optical cables.

First, optical fiber coating material selection and wire drawing process

The reasons for the increase of optical fiber loss mainly include hydrogen loss, fiber cracking, optical fiber stress, through actual detection found that the optical fiber in the optical cable after years of use, its geometric characteristics, mechanical properties, connection characteristics, optical characteristics and other macroscopic properties have basically not changed, through scanning electron microscopy and other methods found that the optical fiber has no obvious microcracks and other abnormal phenomena
.
However, the coating conditions of optical fibers were significantly different, and the attenuation of optical fibers with high modulus, tight coating and large peeling force increased
significantly at 1550nm and 1310nm wavelengths.

Second, the paste filling design

Fiber paste is an oily substance that is in close contact with optical fiber, which is a mixture based on mineral oil or synthetic oil, which isolates water vapor and lubricating buffer the optical fiber, and evaluates the performance
of fiber paste by observing the morphology with the naked eye and testing the oxidation induction period of the ointment.
The increase of acid value after the oxidation of the ointment can lead to an increase in hydrogen evolution, and the oxidation of the ointment has an impact on the stability of the optical cable structure, resulting in a decrease in yield stress, so that the optical fiber will be stressed under the influence of vibration, shock, bending, temperature difference change, topographic geological change, etc.
, weaken the buffering effect of the paste on the optical fiber, so that the reliability of the optical cable decreases
.

The paste is in direct contact with the fiber, which is the most important indirect cause
of deterioration of the fiber performance.

Through the actual inspection of in-use optical cables produced at different times, it is found that the paste slowly denatures
with the change of time.
It usually accumulates into small particles, and then gradually volatilizes, decomposes, and dries up
.
For direct buried or pipeline cables in central China, the typical time for the paste to begin to undergo significant denaturation is 18 years
.

Third, the size of the loose tube

The influence of loose tube size on the life of the fiber optic cable is more reflected in the
comprehensive stress.
When the size is too small, under the changing factors such as temperature changes, mechanical stress, and the interaction between the filler and the optical fiber, the stress of the optical fiber cannot be relieved, which will increase the attenuation of the optical fiber and produce aging phenomenon
.