Inspection and Cleaning are Critical

Clean fiber optic components are a requirement for quality connections between fiber optic equipment. One of the most basic and important procedures for the maintenance of fiber optic systems is to clean the fiber optic equipment.

Any contamination in the fiber connection can cause failure of the component or failure of the whole system. Even microscopic dust particles can cause a variety of problems for optical connections. A particle that partially or completely blocks the core generates strong back reflections, which can cause instability in the laser system. Dust particles trapped between two fiber faces can scratch the glass surfaces. Even if a particle is only situated on the cladding or the edge of the endface, it can cause an air gap or misalignment between the fiber cores which significantly degrades the optical signal.

• A 1-micrometer dust particle on a single-mode core can block up to 1% of the light (a 0.05dB loss).
• A 9-micrometer speck is still too small to see without a microscope, but it can completely block the fiber core. These contaminants can be more difficult to remove than dust particles.

By comparison, a typical human hair is 50 to 75 micrometers in diameter, as much as eight times larger. So, even though dust might not be visible, it is still present in the air and can deposit onto the connector. In addition to dust, other types of contamination must also be cleaned off the endface. Such materials include:

• Oils, frequently from human hands
• Film residues, condensed from vapors in the air
• Powdery coatings, left after water or other solvents evaporate away

These contaminants can be more difficult to remove than dust particles and can also cause damage to equipment if not removed.

Caution: With the high powered lasers now in use for communications systems, any contaminant can be burned into the fiber endface if it blocks the core while the laser is turned on. This burn might damage the optical surface enough that it cannot be cleaned.

When you clean fiber components, always complete the steps in the procedures carefully. The goal is to eliminate any dust or contamination and to provide a clean environment for the fiber-optic connection. Remember that inspection, cleaning and re-inspection are critical steps which must be done before you make any fiber-optic connection.

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