Optical connector and fiber inspection, cleaning and maintenance

Applies to

Inspection and cleaning of all connector and optical fiber types


One of the biggest causes of faults in modern optical networks is contaminated fibers and/or connectors, and this is likely to only become more of an issue as the capacity of datalinks in networks continues to increase into the future.

Even where optical fibers and connectors may not appear at first glance to be contaminated or faulty, dirt can migrate over time due to electrostatic charges whilst connectors and fibers may be damaged through improper user and/or mishandling, so appropriate inspection, cleaning and testing procedures and standards should always be carefully adhered to.

This technical advisory has therefore been produced to amalgamate useful information relating to the maintenance of different optical connectors and fibers used with EXFO products, to help enable users and operators to properly care for their instruments, as well as ensuring they get the best results possible.


General Information

Before starting any inspection and cleaning procedures, you should ensure that you have the right tools and accessories, and that you know how to use them correctly.

Make sure you have the correct Fiber Inspection Probe/s (FIP) and accessories for the connectors and/or fiber types you will be testing.

Information on technical specifications for inspection probes is given in EXFO Application Note 297.


Optical sources emit infrared radiation that is often not visible to the human eye and so always ensure that any optical fibers and connectors being inspected and cleaned are not connected to an active source first; this may require liaison with personnel responsible for operating transmission apparatus to ensure appropriate ports have been deactivated, as well as confirming this with the use of an Optical Power Meter (OPM).

General inspection and cleaning instructions are provided by the first few sections of EXFO Application Note 058.

Various accessories and qualified cleaning consumables (such as the GP-144/145 cleaning swaps and GP-2157 cleaning set) can be purchased from EXFO if required; see purchasing accessories for further information.


Cleaning Optical Bulkhead Connectors

Instruments will possess one or more bulkhead connector to which different EUIs can be attached. The center of the bulkhead consists of a Ø2.5mm ferrule connected to internal fiber which can be inspected, and you should be especially careful not to damage this.

See Cleaning Bulkhead Connectors in EXFO Application Note 058.

See Cleaning EXFO Universal Interface Connectors below for information on removing and refitting EUIs.


Cleaning EXFO Universal Interface Connectors

Different EXFO Universal Interface (EUI) connectors are attached to optical bulkheads to allow mating of a variety of different optical fiber connector types, including those with a Ø1.25mm ferrule.

Polishing EUI-28 (DIN 47256) EUI-89 (FC) EUI-90 (ST) EUI-91 (SC) EUI-95 (E-2000) EUI-98 (LC)

See Cleaning EUI Connectors in EXFO Application Note 058.

When fitting EUI connectors:

  1.  First ensure that the dustcap is closed.
  2.  Squarely insert the EUI into the bulkhead baseplate, ensuring that the positioning notch is correctly aligned whilst being careful not to damage the protruding Ø2.5mm fiber ferrule.
  3.  After gently ensuring the EUI is pressed flush with the bulkhead baseplate, turn the EUI a quarter turn clockwise to lock it.

When removing EUI connectors:

  1.  First ensure that any attached test leads are removed and that the dustcap is closed.
  2.  Turn the EUI a quarter turn counterclockwise to unlock it.
  3.  Squarely remove the EUI from the bulkhead baseplate whilst being careful not to damage the protruding Ø2.5mm fiber ferrule.


Cleaning and Verification of Optical Click/Swap-Out or Modular Connectors

Several instruments now feature click- or swap-out optical connectors, otherwise referred to as modular connectors, and these require some additional precautions and understanding on the part of the operator, to be able to work with them safely and effectively.

To learn more about modular optical connectors and verifying their correct operation, consult verifying modular connectors.


Cleaning Fiber-Optic Adapters

Different Fiber-Optic Adapters (FOA) can be fitted to optical detector ports to allow connection of a variety of different optical fiber termination types.

See Cleaning Fiber-Optic Adapters in EXFO Application Note 058.


Cleaning Optical Detector Ports

Optical detectors are extremely sensitive ports, using comparatively large detector windows for low-loss sensing of incident electromagnetic radiation, and care is needed when cleaning to ensure that the window is not damaged or contaminated.

See Cleaning Detector Ports in EXFO Application Note 058.


Cleaning Optical Fiber Connectors

The terminations of optical fibers, including test jumpers and patch or reference cords, should be inspected and cleaned along with equipment connectors.

For information on the inspection of optical fibers, see The Inspection Phase in EXFO Application Note 191.

For information on the cleaning of optical fibers, The Cleaning Phase in see EXFO Application Note 191.


Cleaning Optical Multifiber Connectors

Multichannel assemblies using Multifiber Push-On (MPO) connectors require special instruments and procedures to properly inspect, clean and test, and a dirty MPO connector has the potential to affect multiple individual fibers.

For more information on MPO connectors and testing, see how to test MPO connectors.