Within the data center environment, especially within switch-to-switch backbone links to the core and to the storage area network (SAN), there is immense pressure to handle extreme data volumes. To process this data, switch-to-switch links are rapidly migrating from 10 Gb/s speeds to 40 and 100 Gb/s and beyond, which is best served by optical fiber cabling. Fiber optic cabling is categorised into single mode fiber and multimode fiber optic cable. Both of them use a kind of or many kinds of glass fiber to transmit data. Among them, single mode fiber may offer the best future proof capabilities, for which it holds advantages in terms of bandwidth and reach for longer distances. In this article, you will get enough information on single mode fiber along with some advantages delivered by this fiber cable.
Figure 1: Single Mode Fiber Application
In optical fiber technology, single mode fiber is optical fiber that is designed for the transmission of a single ray or mode of light as a carrier to propagate at a time. It is commonly used for high speed and long-distance applications. Single mode fiber is also called monomode fiber, and generally has a core diameter of 8.3 to 10µm (micrometers). The single mode fiber optic cable comes in a 9µm diameter that supports Gigabit Ethernet data transfer up to 10 km in distance. Compared to multimode fiber, single mode fiber patch cables have a relatively smaller diameter and carry higher bandwidth. The small core virtually eliminates any distortions that could result from overlapping pulses, providing the least signal interruption and the highest transmission speeds of any fiber optic type. There are many different types of single mode fiber cables, such as cutoff shifted fiber, dispersion shifted fiber, low water peak fiber, non-zero dispersion shifted fiber, and some other else.
Figure 2: Single Mode Fiber Cable
Single mode fiber patch cables essentially send a laser beam through the core with no loss of power. The laser beam goes through an optical switch at the receiving end of these cables. With the help of a fiber optic transceiver, the laser beam is decoded into a more suitable format, which can then be used by the local network. The working principle of single mode fiber has been explained, but do you know where is the targeted application of these fiber patch cables?
The single mode fiber patch cables are used in situations where wiring two locations for distances in excess of 10 miles. With the help of these fiber patch cables, the data can get from point A to point B very fast. It is an ideal solution for a single large location, such as a university or an IT campus.
It is very popular to use the single mode fiber optical cable in backbone systems, especially when the enterprise lacks a truly powerful in-house communications system.
A number of large companies use single mode fiber cables to wire up an entire building or a corporate office. Compared to multimode fiber cable, these fiber patch cords are future-proofing. And this is a effective way to save money on the hardware by purchasing these cables in bulk.
A single mode optical fiber cable has a much greater bandwidth than multimode fiber optic cable. The narrow core of this fiber limits the dispersion of light, which is usually called multi-patch effect. Therefore, the bandwidth capacity of the cable could be increased significantly.
Single mode fiber optic cables are usually used for remote data transmission, including local area network (WAN), metropolitan area network (MAN) and the campus network. They also support the transmission distance at 50 times than multimode fiber. On this type of fiber, the light s usually 1300 nm for shorter distances and 1500 nm for longer distances.
Single mode fiber optic cables provide higher speeds because of their capacity and more minimized bandwidth interference from outside. Single mode cable is capable of transmitting data at up to 40Gb/s over hundreds of kilometers with little integrity loss. Over greater distances, into the thousands of kilometers, this type of cable can send data at speeds of up to 10Gb/s.
The single mode fiber uses a laser to transmit the signals. This type of fiber is designed as a step index, meaning that the core has only one refractive index to carry the light signal. Chromatic dispersion is caused by the intense laser filtering into the cladding causing pulse overlap and distorted signals. The single input mode of the SMF limits light scattering, which in turn eliminates waste and increases transmission speeds. In addition, a single mode fiber is immune to external noise, including electromagnetic interference (EMI) and radio frequency interference (RFI).
Figure 3: Dispersion of Single Mode Fiber
Attenuation refers to the higher weakness of fiber optic signals as the distance covered by the cable increases. This is what one called dB loss. Single mode fiber cables perform better because the fiber core of single mode fiber is only 9 µm in diameter (as mentioned above). This means the light that passed through these fiber optical cables is not reflected too many times, which keeps the attenuation to a minimum. So the single mode fiber support long range connections and applications that require higher speeds. The following table shows the attenuation between single mode fiber and multimode fiber:
|9/125 Single Mode Fiber Simplex||50/125 OM3 Multimode Fiber|
|Attenuation at 1310 nm||0.36 dB/km||Attenuation at 850 nm||3.0 dB/km|
|Attenuation at 1550 nm||0.22 dB/km||Attenuation at 1300 nm||1.0 dB/km|
Recent innovations of fiber optic technology have pointed to a bright future – we could achieve extraordinary data transmission speeds up to 400 Gbps in the near future. The IEEE P802.3bs (200GBASE-DR4/400GBASE-DR4) and IEEE P802.3cd (100GBASE-DR) standard, which are still pending as of now, is meant to support 400 Gb/s over a single mode fiber through a distance of 500 meters with 8-fiber MPO/MTP solutions. These applications will have four fibers working at the same time, transmitting at a speed of 100 Gb/s, with four fibers receiving the data at a speed of 100 Gb/s. This is one of the crucial reason for choosing single mode fiber for making your fiber optic connections future proof over 400 Gb/s.
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