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What is Carbon Polyimide?
Carbon polyimide is a protective coating for optical fibers designed for harsh environments. It combines a thin, hermetic carbon layer with a high-temperature-resistant polyimide coating, protecting the fiber from hydrogen, moisture, chemicals, and elevated temperatures while helping maintain its optical performance.
The carbon layer acts as a barrier against hydrogen and moisture ingress, while the polyimide coating provides mechanical protection and resistance to high temperatures. This combination makes carbon polyimide particularly suitable for specialty optical fibers used where conventional acrylate coatings cannot withstand the environmental conditions.
Carbon polyimide coatings are therefore used in demanding fiber-optic applications where long-term reliability and stable optical performance are required, including high-temperature sensing, radiation environments, and other harsh-environment applications
HOW carbon polyimide Works
Carbon polyimide protects an optical fiber through three complementary functions.
Hermetic Protection
The carbon layer forms a very thin, continuous barrier around the silica glass. Its hermetic properties help limit hydrogen and moisture ingress, reducing the risk of environmentally induced optical losses.
Thermal and Mechanical Protection
The surrounding polyimide coating protects the fiber from mechanical damage while maintaining its properties at elevated temperatures. Polyimide is also suitable for cryogenic applications, making it useful across a broad temperature range.
Long-Term Fiber Performance
By limiting environmental exposure while maintaining the mechanical integrity of the fiber, the coating helps preserve optical performance in demanding operating conditions. This is particularly important for specialty fibers used for distributed sensing, radiation monitoring, and other applications where the fiber itself is exposed to the environment.
