“Optical hygiene” is a term used to describe the cleanliness of fibre end-faces in an optical network. Microscopic particles of dust, lint, or residue present on the core of a fibre can generate significant back reflections that can result in optical power degradation and instability in the source of the optical signal. The mating of dirty connectors can also embed particles into the glass surface of the fibre, creating scratches or pits that generate further losses. Regular application of inspection and cleaning protocols prevent and correct poor hygiene, and as a result, optimise network capacity and minimise network downtime.
Inspection
Inspection of fibre end faces is typically carried out with a fibre inspection microscope (“fibre scope”). A fibre scope is used to check the condition of fibre connectors (patch cords or bulkheads) before mating with other fibres or network component to avoid damage to the fibre end-face.
The cross-section of a fibre end-face has three areas: the core, cladding, and ferrule. As the majority of light propagates through the core, particles that obstruct the core will have more impact than particles obstructing the cladding or ferrule.
The fibre end-face is typically cleaned if a particle is found to be in close proximity to the core, and then re-inspected.
Cleaning
Fibre cleaning is used to reduce contamination of the fibre end-face and provide a quality connection between fibre optic equipment. Typical cleaning techniques use lint-free and anti-static micro-fibre fabric to achieve this.
Typical contaminates range from 2 – 5 µm and include:
- Airbourne dust
- Residue
- Skin oil
- Distilled water
- Salt water
- Alcohol
- Hand lotion
- Graphite
- Clothing lint
Applications
Fibre inspection and cleaning is successfully used in the following environments and components:
- Telecom central offices
- Data centres
- Cable television headend
- Outside plant and fibre to the home (FTTH)
- Fibre to the antenna (FTTA) for WiMax and cellular networks
- Fibre optic broadcasting including HDTV
- Fibre optic military and civilian aviation
- Military and civilian maritime optical networks
- Fibre optic satellite communication systems
- Parallel optics transceivers