6.6.1 Fiber Patch Cord
In a typical GPON network, a fiber is connected directly to the customer ONT/ONU. To test the GPON network, the fiber must be
temporarily disconnected from the ONT/ONU and inserted into the MTTplus-420 OLT port. An additional fiber patch cord is then
used to connect the MTTplus-420 ONU port to the ONT/ONU modem.
The patch cord and optical connectors play a critical role in fiber measurements. Ensure that a high quality patch cord is always
used, as this can and will have profound performance on test results and traces.
Color Coding
The buffer or jacket on patch cords is often color-coded to indicate the type of fiber used.
Connector boot
The strain relief “boot” that protects the fiber from bending at a connector is color-coded to indicate the type of connection.
Connectors with a plastic shell (such as SC or E2000) typically use a color-coded shell.
Color Code of Jacket
Definition or Meaning
Yellow
Single mode fiber
Orange
Multimode fiber
Aqua
10G laser-optimized 50/125um multimode optical fiber
Grey
Obsolete color code for multimode fiber
Blue
Sometimes used to designate polarization maintaining fiber
Color Code of Connector Boot
Definition or Meaning
Blue
Singlemode, Physical Contact (PC), 0°. Sometimes used for polarization-
maintaining optical fiber.
Green
Singlemode only, Angle Polished (APC), 8°
Black
Singlemode, Physical Contact (PC), 0°
White
Singlemode, Physical Contact (PC), 0°
Red
High optical power. Also used to connect external pump lasers or Raman
pumps.
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