NOTE
Besides the optical characteristics of an optical fiber it is important to consider the physical environment in which it will be used. The primary coating is a major factor in the fiber ability to withstand a given environment over time. It is important to make the distinction between this coating and the different protective structures which are added afterward. These structures are designed according to the know-how of cablers whereas the coating is really part of the fiber draw process.

POLYIMIDE HIGH TEMPERATURE COATING
- High temperature:300°C(up to 400°C for short period).
- High reliability
- Vibration resistance
Many applications expose fibers to harsh environments such as high temperature, high pressure or corosive fluids combined sometimes with small bend radius. This is true for avionic applications  but also for other applications such as medical, geophisic, industry, etc. For these applications “PyrocoatTM” (Trade mark of OFS) offers a solution up to 400°C with a very thin layer (15µm) of polyimide. This coating can be applied to most fiber types: singlemode, graded index or step index as well as hermetic fibers.

CARBON/POLYIMIDE HERMETIC COATING
- Improves aging performances
- Improves reliability
- Prevent hydrogen penetration
This type of coating has been developped to dramatically improve fiber resistance to difficult environments combining high pressure and high temperature and to avoid hydrogen migration in the silica which rapidly increases attenuation and reduces resistance.
Hermeticity is obtained by a thin layer of carbon applied during the draw process which makes a permanent barrier to hydrogen. The N factor indicating corrosion resistance is above 100 compared to 20 for standard fibers. Fatigue resistance is five times better.
Fiber is further protected by a more traditionnal coating such as ETFE or Polyimide.

NOTE: Sorry the technical datasheet in PDF format is only available in French. Please contact SEDI.