Know Your Fiber Terminology: From Fiber Cable to Basic Polarity

The key to understanding the nuances of fiber, along with determining which fiber solutions are the right fit for your application, begins with understanding basic fiber terminology. Words and meanings matter. If you want to communicate effectively about fiber, then it’s critical to use the right terms from the start so you get the results you want.

But when it comes to common fiber terms, we’ve noticed industry confusion. What’s the difference between fiber cable vs. fiber cabling? Are orientation and positioning the same? To answer your questions, we created this blog to serve as your go-to resource for the fiber terminology you hear most often.

As you look up the correct definitions for everything from fiber cable to common fiber polarity terms, consider it your guide.

Fiber Cable Terms

Fiber

The term “fiber” or “fiber optic” refers to the technology and components being used to transmit information. Fiber is made up of a thin-filament glass core, cladding and acrylate coating.

Fiber Optic Cable

When a fiber(s) is wrapped in a protective jacket and can be installed, then that final product—the fiber + the jacket—is considered a fiber optic cable. Fiber optic cable types can include distribution, breakout, loose tube, etc. Different types of cables are designed to be used in different applications and environments.

Fiber Optic Cabling

To connect a fiber cable to equipment or a device, some type of connectivity, such as a connector, must be used. The term “fiber optic cabling” describes not only the fiber cable, but also the connectivity that accompanies it.

Fiber Cable Assembly

Bringing a fiber cable, connector and adapter together creates a cable assembly. A cable assembly can be made up of one or more cables. Patch cords or MPO trunks are both examples of a fiber cable assembly.

Duplex Fiber

When two simplex fiber cables are connected side by side using a zip cord, this creates a duplex fiber that supports two-way data transmission. One fiber transmits data from point A to point B, while the other fiber transmits data from point B to point A.

Duplex Transmission

Duplex transmission enables two-way communication on the same carrier. A half-duplex transmission sends a signal in both directions—one direction at a time. Full duplex supports signal transmission in both directions at the same time. In fiber, this technology is often referred to as “bidirectional,” or “BiDi.”

In a duplex transmission application, such as include workstations or networking hardware, each fiber connects the transmitter on one end to the receiver at the other end to maintain a connection.

Fiber Connectivity Terms

Discrete Connector

A discrete connector is a single-fiber connector in a ferrule, such as an LC or SC connector.

Duplex Connector

A duplex connector consists of two discrete connectors that are joined together to send and receive signals. An LC duplex connector is an example. Sometimes the two connectors are molded together; sometimes they aren’t.

Array Connector

A connector that has multiple fibers within a single ferrule, such as an MPO connector.

Fiber Polarity Terms

Polarity

This term describes the method used to position optical fibers in a way that ensures connectivity between transmitters and receivers.

Types

This term is used to define the configuration of a component. There are two component Types used in fiber systems: cable assemblies and couplers. Standards define multiple configuration Types (A, B, C, U1, U2, A-A, and A-B), but there are additional needs-dependent Types as well.

Methods

Methods are schemes that define the arrangement of component Types used to achieve the desired fiber polarity.

Orientation

The relative position of the keyed part of a connector or an adapter is its orientation (KeyUp/KeyUp or KeyUp/KeyDown, for example).  It can also be described as “aligned” or “unaligned” keys (important with VSSF connectors) and is technically more accurate; KeyUp/Down nomenclature presumes a vertical orientation.

Pinning

Fiber connectors do not generally have genders; only MPO and array connectors have pins to ensure mateability. Pins precisely align mating fibers. If mating connectors use alignment pins, then one plug must be pinned while the other is unpinned.  This is sometimes referred to as “male” or “female,” but more correctly as “pinned” or “unpinned.”

Positioning

The correlation between the specific fiber strand in a connector ferrule is referred to as “positioning.”

Port Identification

Port identification refers to the identifier port (often a label, color or number) used on a fiber.

Ready to continue learning about Fiber?

Now that you’ve got your definitions down, you can watch a webinar series we created to help you learn more.

While the series focuses primarily on fiber polarity, the first webinar provides helpful information about fiber basics.

Related resources:

• Singlemode or Multimode Fiber: Demystifying the Differences
• Create Your Own Fiber Playbook to Design, Install & Manage Fiber
• 9 Simple Rules for Achieving Fiber Polarity