The Basics of Fiber, Made Simple

Understanding Fiber

Fiber optics is the backbone of communications, delivering fast and reliable data. With various cable and connector options, understanding the basics helps you choose the right components for your setup.

This page breaks down key topics, explaining the difference between Singlemode and Multimode fiber while highlighting important components of a fiber optic cable to help you make informed decisions.

Singlemode
vs. Multimode Fiber

Fiber optic cables come in two main types: singlemode and multimode. Each serves a different purpose and can often be identified by its color.

Singlemode Fiber has a very small core (~9 microns) that carries light in a single path, making it ideal for long distances and high-speed networks. It’s the most commonly used fiber type today and is typically yellow in color.

Multimode Fiber has a larger core (50 or 62.5 microns) that allows multiple light paths, which can cause more signal dispersion. It's best for short-distance runs like within buildings and is usually orange or aqua depending on the grade.

To ensure proper signal transmission, never mix singlemode and multimode fiber in the same network. Whichever type your fiber network uses, it should remain consistent across all cabling, including patch cords and jumpers.

Common
Fiber Connectors

Fiber connectors are installed at the ends of fiber cables to connect them to switches, patch panels, or transceivers. They differ in size, locking style, and use case, and most are available in both singlemode and multimode versions. Below are some of the most common connector types you’ll encounter:

  • SC: A square, push-pull connector commonly used in patch panels, wall outlets, and some older telecom installations.
  • LC: A compact connector with a latch mechanism, often found on switches, routers, and SFP transceivers in modern networks.
  • ST: A round, twist-lock connector typically used in older enterprise setups, industrial systems, and legacy fiber networks.
  • MTP/MPO: A high-density, multi-fiber connector designed for backbone links, large-scale patching, and high-speed data center applications.
Understand the parts that power your connection.

Fiber Cable Components

Beyond the type of fiber used, the physical makeup of a cable plays a role in how it functions and connects. From how it's polished to how many fibers it contains, these details impact performance and compatibility.

In the next sections, we cover components that help define how a fiber cable is used in the field. Understanding these basics helps you choose the right gear and avoid mismatches during installation.

Patch Cable
vs. Bulk Fiber

Fiber optic cables are available as patch cables or bulk spools. Your choice depends on distance, environment, and installation needs.

Patch Cables are pre-terminated and ready to plug in, making them ideal for connecting devices like switches or patch panels.

Bulk Fiber comes uncut and unconnected, requiring field termination or splicing, best for custom runs and outdoor setups.

APC
vs. UPC

APC and UPC refer to how fiber connectors are polished, impacting signal performance. Each type has a distinct color for easy identification.

APC connectors are polished at an angle and are green, ideal for applications needing low signal reflection like FTTx or precision systems.

UPC connectors have a flat polish and are blue, commonly used in server rooms and commercial network installations

Simplex
vs. Duplex

Simplex and Duplex refer to the number of fiber strands in a cable and how data flows. Each serves a purpose depending on the application.

Simplex cables contain a single fiber strand for one-way data transmission, ideal for situations where communication flows in one direction.

Duplex cables have two fiber strands, one for sending and one for receiving, allowing two-way communication, commonly used with networking equipment.

Built to Bridge Every Break

Making the Connection:
Fiber Splicing

Fiber splicing joins two fiber optic cables together to extend the fiber or repair breaks. The two main methods, fusion and mechanical, create a continuous signal path with minimal loss. Choosing the right splicing method helps maintain network integrity and ensures long-term performance.

Splicing is essential for building clean, reliable fiber networks, whether you're running long distances or managing connections in tight spaces. It’s a critical step in installations where pre-terminated cables aren’t practical or when making permanent repairs in the field.

Precision Splicing, Minimal Loss

Fusion
Splicing

Fusion splicing melts and fuses fiber ends together for a strong, low-loss connection. It's ideal when signal performance matters most.

Fast Fixes in the Field

Mechanical
Splicing

Mechanical splicing aligns fibers in a sleeve without heat. It’s quick and convenient, with higher signal loss.

Have Questions? Let’s Talk.

Need help choosing fiber components? We're here to help.

Contact Us