Introducing A1 Fiber Cables

Introducing A1 Fiber Cables

There are 2 modes in optical fiber; single-mode fiber optic cable and multi-mode fiber optic cable. Single-mode optical fibers are further classified into G.652, G.653, G.654, G.655, G.656, and G.657 by the ITU-T. While each single-mode fiber type has its own use, we’ll discuss A1 fiber, A1 fiber optic cable, its performance, and its features in this article.

What are A1 fiber cables?

G.657.A1 or A1 Fiber compliant cables are reliable, high-performance single-mode fibers. In addition, this fiber optic cable is backward compatible with existing networks and has improved bending properties.

They are excellently suited for the system demands of LAN networks, with the lowest attenuation, flawless fiber geometry, and tight fiber diameter tolerances. These fiber optic cable types are used to bridge longer distances in LAN cabling and in FTTX systems.

A1 Fiber Cables

Difference between A1 fibre and A2 fibre cables

Bend-insensitive single-mode fiber optic cable is covered by ITU G.657. ITU-T G.657 optical fiber cables have steadily expanded the entire optical fiber cable industry since their launch. ITU-T G.657 fiber optic is divided into two sections:

  • Category A fibers for access networks
  • Category B fibers for short distances at the end of access networks in bending-intensive situations (e.g.: buildings).

Each of the two fiber optic cable types (A and B) has two sub-categories:

  • G.657.A1 and G.657.A2
  • G.657.B2 and G.657.B3

Unlike G.657.A1 Fiber cables, G657.A2 fibers or A2 fiber cables are used in advanced cable network installations, where stronger bend resistance is necessary for smaller cable jointing pits, and cable and device miniaturisation is possible. At 1550nm, the G657A2 fiber Mode Field Diameter is 9.8m. When splicing the two different fibers together, splice losses are slightly higher.

G657.A1 G657.A2
A1 fiber cables A2 fibre cables
10 mm minimum design radius 7.5 mm minimum design radius
Larger distances Smaller distances
Lower bend resistance Higher bend resistance
Higher cost deployment Lower cost deployment

Backward compatibility with G.652D (MFD of 9.1 mm) is provided by A2 fiber optic cable, allowing service providers to create high-density fiber networks that are service compatible with legacy fiber networks.

A2 fiber optic cable compatibility

Features and benefits of A1 fiber cables

Optical fiber cables have been made more flexible, allowing for easier installation in restricted spaces. Smaller cabinets, pedestals, enclosures, and terminations are essential when space is limited. In addition, an installation that is more engineer-friendly results in less rework.

As fiber gets closer to the residence, there are a variety of uses of optical fiber where a bend-optimized A1 fiber can help the system function better:

  • Low-count cables: As the number of fibers in a cable drops, it is more likely that it will bend with a radius of 30mm or less.
  • High-density connectivity: A1 fiber cables are excellent for fiber optic patch cords in high-density applications like central offices and distribution cabinets.
  • Small enclosures: The capacity to have bends with radii as small as 10mm, has enabled the creation of more compact sections for FTTx applications.
  • Low-temperature applications: Patch cords and cables work better at temperatures as low as -40°C, thanks to increased micro-bending of the bend-optimised fiber.
  • Compact cable designs: The use of bend-optimised A1 fibers results in minimal attenuation after cabling.
  • Drops and in-building applications: Bend-optimised A1 Fiber supports this application without the drawbacks of G.657B fiber.

STL Tech’s A1 Fiber Solutions

While there is a lot of ambiguity about how networks will evolve in the future, it is obvious that this decade will see a lot of change in the telecom sector. To allow for more next-generation network deployment, what all of these networks have in common is the deployments that increasingly rely on fiber optic cable.

STL is the world’s top optical fiber cable and fibre optic solutions provider. Our lower bend loss fiber optic is ideal for your network, allowing for higher network performance and lower installation costs. For 5G and FTTx applications, we provide Bend Insensitive Single Mode A1 Fibre (BISMF) and Non-Zero Dispersion Shifted Single Mode A1 Fibre (NZDSF) solutions with diameters of 250um and 200um. We also provide customised cables according to customers’ specifications.


  1. What are the 2 types of fiber optic cable?

There are two modes in optical fiber – single-mode and multi-mode:

Single-mode fiber optic cable or single-core fiber optic cable is a single strand of glass fiber with a substantially smaller diameter of 8.3 to 10 microns that contains only one mode of transmission (most applications require two fibers). Single-mode cable has a single light path and may go up to 100 kilometers allowing just one mode to propagate, usually 1310 or 1550nm.

Single Mode Fiber
Multimode Fiber

Multi-mode cable has a somewhat larger diameter, with light carry component diameters ranging from 50 to 100 microns, allowing it to carry many light rays (modes) at the same time. Two fibers are employed in the majority of multi-mode fiber applications.

  1. What is the single-mode fiber type?

Single-mode fiber (also known as fundamental or mono-mode fiber) allows only one mode to propagate at a time. Hence, mode delay differences are not possible. Single-mode fibers have large bandwidths (e.g., >40 GHz) and are thus well-suited to long-haul and high-capacity circuits. Single-mode fiber connector types are employed in many situations where data is delivered at several frequencies (WDM Wave-Division-Multiplexing).

Single-mode fiber is employed in many situations where data is delivered at several frequencies (single-mode on one single fiber). Only the lowest order bound mode can propagate at the wavelength of interest, which is typically 1300 to 1320nm in single-mode optical fiber.

  1. What is the advantage of the G 657 fiber?

As optical fiber cables have been made more flexible, allowing for easier installation in restricted spaces, ITU-T G.657 optical fiber cables have steadily expanded the total optical fiber cable industry since their launch.

  • ITU-T G.657 optical fiber cable has flexible properties that make it easier to install in streets, buildings, and residences.
  • Smaller cabinets, pedestals, enclosures, and terminations are important in tight spaces (e.g., apartment buildings).
  • Less rework due to a more engineer-friendly installation.
  • The total cost of ownership (TCO) and operator roll-out costs of an FTTH network are reduced by using ITU-T G. 657 optical fiber cable.
  1. What is the difference between single-mode and multi-mode fiber?

The difference between multi-mode and single-mode fiber is as follows:

Single-mode optical fiber has a greater transmission rate and can travel up to 50 times farther than multi-mode fiber, but it is also more expensive. The single-mode fiber optic core is substantially smaller than that of the multi-mode fiber. Any distortion caused by overlapping light pulses is practically eliminated, resulting in the least signal attenuation and fastest transmission speeds of any fiber cable type.

Multimode fiber carries numerous light rays (modes) at the same time. The bigger core simplifies connections and allows for the use of lower-cost LED and VCSEL technologies operating in the 850nm window.

Optical Multimode Fiber

This table shows distance differences between single-mode and multi-mode optic fibers for ratified standards only:

Single-mode and multi-mode optical fibers standard
  1. Where is the single-mode fiber used?

Single-mode fiber like the A1 fiber is almost universally used in telecommunications at a distance of 1 km or more. And the use of optical fiber in single-mode is most commonly at wavelengths of 1300 nm and 1550 nm, where attenuation is low, and sources and detectors are readily available.

A tiny diametral core in a single-mode optical fiber optic cable permits only one light mode to propagate. The use of optical fiber cable in a single-mode is seen in Telcos, CATV providers, and colleges and universities in long-distance, higher-bandwidth networks.

Leave a Reply

Your email address will not be published. Required fields are marked *

Introducing A1 Fiber Cables

Latest Blogs