Does my instrument have APC or UPC connectors?

Applies to

All EXFO instruments with physical contact fiber connections.



It is well known that we should not connect Angled (APC) connectors to Flat (UPC) connectors. Doing so will create an optical connection that;

  • will have a strong reflection ( -15 dB or stronger),
  • will have a high loss ( 10 dB or more),
  • and may damage the end-face of the connectors.


Generally when manipulating connectors the color codes make it easy to identify, Green for APC, and BLUE for UPC. Sometimes however it may not always be 100% clear whether there is an APC or a UPC inside the optical port.

The information that follows will help you to identify the connector type in your EXFO instrument.

1. EXFO universal interface (EUI)

  • Many EXFO products use a universal adapter mounted on a base plate on the optical port.


  • In the image above, we see the SM/Live OPM port of an OTDR that has a green gasket on the base-plate.
  • The green gasket provides confirmation that this specific port has an APC connector. 


  • In the image above there is no green gasket which is confirmation that the interior connector is UPC.

2. Colored Bulkhead adapters

  • Some products where universal adapters are not fitted, will have the standard Green (APC) or Blue (UPC) bulkhead adapters on the optical ports.



3. Stickers and other markings

  • Some products may have ports where there are no color markings. Most of these will have clear inscriptions that indicate the connector type.
  • Two examples are shown below.


4. Contact Support

  • Although it should be quite rare, if there is any doubt regarding the connector type, you can contact our technical support team.
  • Please have the serial number of your product available, so that we can validate in our manufacturing database.