Fiber optic cables made their first appearance in long-distance networks between cities and countries. The increasing bandwidth requirement, which was accelerated by the Internet with the rapidly increasing applications (gaming, video, streaming, etc.), has resulted in fiber optic networks being expanded more and more worldwide. Today, the bandwidth requirement is so high that the goal is being pursued worldwide to connect all houses and apartments with fiber optics (FTTH – Fiber to the Home).
However, fiber optic technology also dominates in the networking of computers, machines and servers in companies and in data centers and cannot be replaced by any other transmission technology today.
Depending on the area of application, different requirements are placed on fiber optic cables today. In addition to the mechanical structure and the physical properties of the cable, the nature or property of the glass fiber is also of great importance.
In addition to the mechanical and physical structure of a cable, there are also some properties to consider for glass fibers:
- Number of fibers in the cable
- Color coding
- fiber types
- Step index, graded index and single-mode fiber
- NZDS fiber for DWDM systems
- Low water peak fiber
- PM fiber "Polarization Maintaining"
- Bend-insensitive fibers for FTTH installations
All fiber types are subject to an ITU-T standard, also known as the ITU-T Recommendations. These describe the geometric properties and the transmission properties of multimode and singlemode fiber optic cables. There are currently seven ITU-T Common Recommendations in force at the time of their publication: ITU-T G.651.1, ITU-T G.652, ITU-T G.653, ITU-T G.654, ITU- T G.655, ITU-T G.656 and ITU-T G.657.
50/125µm graded index multimode fiber
ITU-T G.651.1 was developed on the basis of the ITU-T G.651 standard, which is no longer valid. This standard defines the 50/125µm graded index multimode fiber that can be used in the optical transmission range in the 850nm band or 1300nm band or alternatively in both ranges. This multimode fiber can be considered as a bend-insensitive fiber. The G.651.1 fiber is mainly used in corporate networks to connect LAN switches or in data centers.
Standard single-mode fiber for WDM applications
ITU G.652 is the first single-mode fiber standard specified by the ITU-T. This includes four revisions, namely G.652.A, G.652.B, G.652.C and G.652.D. Due to the low power, the types G.652.A and G.652.B fibers are rarely used in WDM networks. The G.652.C and G.652.D fibers are mainly used in the wavelength range between 1310nm and 1550nm due to a reduced water peak (ZWP - Zero Water Peak). These two fiber types are also well suited for CDWM (Coarse Wavelength Division Multiplexed) applications. G.652.D fiber is among the most advanced fiber technology that not only offers the maximum return on your investment, but is also recommended for most use cases. Applications are mostly wide area networks (WAN), metro networks/city networks, access networks and FTTx networks.