Single-mode optical fiber - which type is best?


Following on from our earlier articles on Fiber Optics Technology (read here on Fiber Optics Theory) we now look closer at the single-mode fiber and explore the two most commonly used types – ITU-T G652D and G657A2.

Designs of single-mode fiber have evolved over the decades and present day options offer most often than not, the G652D fiber. This backwards compatible fiber has been used in networks for over 30 years and offers respectable attenuation (the amount of light lost between input and output) and provides marginally lower loss transmission which is better in facilitating long distance communication links (up to and greater than 100km). However, the biggest difference between G652D and G657A2 can be found in their ability to bend.

Compared to G652D fibers which have limited bend resistance, the G657A2 fiber offers an improved bend radius and flexibility which may allow for better cable management and routing in congested areas and also allow for increased density in high-density patching fields. G657A2 fiber is becoming more popular for use in advanced access cable network installations, where bend resistance is required for smaller cable and cords installation radii, providing for low-cost installation, miniaturisation and higher density connectorization.

The below diagram clearly illustrates the difference in bending radii for G652 and G657 fibers