Loss of Optical Link

For fiber-based cabling, data transmission is based on the light as the transmission medium. We know that in the transmission process, the loss of light power is inevitable. When connecting components, there will be insertion loss; when optical signals are transmitted over fiber optic cables, there will be attenuation. In addition, the material of optical components and the operation during the cabling have an influence on the amount of loss, which will determine the level of network performance. Therefore, it is necessary to reduce the loss of optical link to a minimum. This article aims to talk about loss of optical link and give some suggestions about loss control.

Insertion Loss

A complete optical link is finished by the connectivity between different fiber optical components, and no matter what kind of cabling system you are going to deploy, insertion loss is inevitable Take fiber optic connector for example, there is no perfect loss-less connector. It is important to note that even the highest quality connectors will also have insertion loss because of the alignment and the cleanliness. Structured with MT ferrule, MTP connector still has insertion loss which is rated at 0.35 dB maximum. It is impossible to ensure that fiber optic connector does not get dirty. However, dirt and dust can completely obscure the light wavelength and create huge losses.

Attenuation

When light travels through the core of fiber optic cable, the strength of it surely becomes lower. Naturally, the signal strength becomes weaker. This loss of light power is generally called attenuation and it locates on two aspects: internal reasons and external causes, which are also known as intrinsic fiber core attenuation and extrinsic fiber attenuation. Internal reasons of fiber optic loss are caused by the fiber optic cable itself, which is also known as intrinsic attenuation. Basically, there are two main causes of intrinsic attenuation: light absorption and scattering. As for extrinsic fiber attenuation, it is usually caused by improper handling of fiber optic cable. And there are two main types of extrinsic fiber attenuation: bend loss and splicing loss. Besides, fiber optic splicing can also result in extrinsic fiber attenuation.

Loss Control

For the reduction of insertion loss, it is necessary to use fiber optical components of high quality, such as for high-density cabling, MTP fiber connector is preferred.

For the purpose of reducing the intrinsic fiber core attenuation, it is necessary to select the proper fiber optics and suitable optical components for the applications, such as for short distance MTP connectivity, MPO to LC breakout cable utilizes multimode fiber OM3 or OM4; for long distance optical link, single-mode fiber is better than multimode fiber.

For reduction of extrinsic fiber attenuation, it would be better to handle the fiber optic cable properly and splice it with cautious.

Conclusion

Since efficient transmission of light at the operational wavelengths is the primary function of fiber optics needed for a range of applications, the loss of optical link and the potential for its minimization are of great importance in the efficient and economic use of fiber optics. It is essential to take the loss into consideration and reduce the loss to a minimum as much as possible during the cabling process. FS.COM provides high quality fiber optical components with low loss and ensure the high performance of network, such as MPO fanout cable, MPO patch panel, MTP cassette and so on. 

Applications of Serial Transmission and Parallel Transmission in Network

In the age of the Internet, we are not unfamiliar with data communication, which refers to the process of transferring data signals between two or more devices. Basically, there are two methods used to transmit data signals: serial transmission and parallel transmission. To put it simply, serial transmission sends data bits one after another over a single channel， while parallel transmission sends multiple data bits at the same time over multiple channels. Both of them are commonly used in network applications and this article will focus on applications of serial transmission and parallel transmission in network.

Application of Serial Transmission

As in serial transmission, bits are sent sequentially on the same channel (wire), one bit at a time, the cost for wires is low but the speed of transmission is slow. In 10G network, serial transmission is usually utilized. For example, a duplex LC fiber that consists of one fiber for transmitting 10G data signals and one fiber for receiving 10G data signals is typically used to completer the data link. In high-density network applications, it is easy to find LC duplex patch cables deployed to connect different network devices.

Application of Parallel Transmission

In parallel transmission, multiple bits (usually 8 bits or a byte/character) are sent on different channels (wires, channels) simultaneously over the same cable. Compared with serial transmission, parallel transmission has a faster bit rate, and the higher cost since multiple wires cost more than one single wire. Parallel transmission is usually used in 40G and 100G network because it can transfer more data signals and achieve higher speeds. For example, MTP trunk cable, terminated with MTP/MPO fiber connector on each end, can be used to achieve the connectivity. In 40G networking applications, a 12-fiber MTP fiber connector is used: 10G is sent along each channel or fiber strand in a transmit and receive direction, and 8 of the 12 fibers are used to provide 40G parallel transmission; in 100G network applications, a 24-fiber MTP fiber connector is used: 10G is sent along each channel or fiber strand in a transmit and receive direction, and 20 of the 24 fibers are used to provide 100G parallel transmission.

Note: Parallel transmission can also be applied to 25G duplex fiber pairs to reach even higher speeds or reduce the number of fibers required at a given speed. For instance, a 100G channel would require four 25G duplex fiber pairs instead of ten 10G duplex fiber pairs.

Conclusion

In network applications, serial transmission is often used in 10G connectivity, while for 40G and 100G connectivity, parallel transmission is preferred. Hope you could acquire some useful information from the article, and have a better understanding of these two data transmission methods. In addition, you can find fiber optic cables mentioned above at FS.COM. Some other fiber optics are also available, such as 24-fiber MPO MTP loopback, MTP to LC breakout cable, MPO fiber patch panel and so on. 

Focus on MTP-link

Characterized by providing ideal plug-and-play solutions for structure cabling, pre-terminated cabling system has gained great popularity among data center manager in recent years, and it is considered as the norm for data center network deployment. In this cabling system, optical link is accomplished by pre-terminated cabling assemblies, such as MTP/MPO trunk cable, MTP/MPO to LC breakout cable, MTP/MPO cassette and MTP/MPO fiber optic patch panel. It not difficult to find that all these MTP/MPO fiber optic cable assemblies are based on the structure of MTP/MPO connector. And two types of MTP/MPO connectors—12 fiber MTP connector and 24 fiber MTP connector are commonly used for 40G and 100G transmission. This article will focus on MTP-link and share share some opinions about MTP-link performance with you.

About Space Utilization

High-density cabling makes the available space in data centers always precious. MTP/MPO fiber optic cable assemblies used in MTP-link that contributes to promoting space utilization are reputably appraised by data center managers. With massive cables being adopted in the data centers to carry out data transmission, MTP-link offers cabling solutions with much higher density and flexibility for data center upgrades.

About Insertion Loss

As well know that insertion loss is inevitable during the cabling. Generally, lower overall optical loss allows more margin for the network to operate, or in the case for some users, offers the option of more connections for patching locations. Therefore, components characterized by low insertion loss will be preferred. For both 12-fiber and 24-fiber MTP/MPO connector performance, the industry standard product rating is 0.5 dB maximum. And using low-loss ferrules, both 12 fiber MPO connector and 24 fiber MPO connector can be rated at 0.35 dB maximum. What’s more, there is no need to worry about higher fiber count will lead to higher insertion loss, because when using proper polishing techniques, 24-fiber MPO/MTP terminations can meet the same performance levels as 12-fiber MPO/MTP assemblies.

About Fiber Utilization

Both 12-fiber MPO cable and 24-fiber MPO cable can be used in 100G applications. When used in 4x25G solutions, 4 fibers of 12-fiber MPO cable will remain unused. As for 24-fiber MPO cable, it can be converted into three 8-fiber 100G channels that run over one cable, with all 24 fibers used to support data transmission. Maybe you feel confused about this, let me take an example. If you need to support twelve 100G channels with the 4x25G standard, by using 12-fiber MPO cable, you will need to install 12 connectors, or 144 fibers total, with 33% of the fiber wasted; while by using 24-fiber MPO cable supporting the same 12 channels, only 4 cables would be required, using 96 fibers total, at 100% fiber utilization.

About Network Performance

It is self-evident that MTP-link offers consistent high levels of network performance for improved network integrity, because the assemblies are factory terminated and the transmission testing is performed by the manufacturer before shipment. This will reduce the likelihood of many problems that may occur with field terminations. Also, testing and troubleshooting time can be greatly saved.

Conclusion

By using MTP components, MTP-link can provide fast installation, high density and high performance cabling for data centers. As 40G and 100G Ethernet is now a trend and hotspot for data center cabling system, MTP-link is a great option for data center managers and the network deployment will benefit a lot from this cabling solution. I hope after reading this article, you can have an in-depth understanding of MTP-link.

How Much Do You Know About Fiber Loopback Cable?

With the widespread adoption of 40G and 100G Ethernet network, cabling system in data centers becomes more and more complicated. Choosing a suitable cabling solution is important, but ensuring the normal operation of optical components is the basic requirement. Therefore, it is necessary to carry out fiber optic testing. On the market, there is an useful tool that can provide cost-effective solution for fiber optic testing application—fiber loopback cable. Have you ever used it? How much do you know about it? This article will guide you to know more about fiber loopbackc able.

Overview of Fiber Loopback Cable

Fiber loopback cable is terminated with two connectors on each end of the cable, forming a loop. From the figure below, we can see that there is a black enclosure outside the optical cable. This improved structure is aimed to protect the cable. In addition, this design makes the fiber loopback cable more compact in size and stronger in use. Fiber loopback cable is used to provide a medium of return patch for an optical signal, especially for fiber optic testing applications and network restorations. It can determine where the fault might lie. Similar as fiber optic patch cord, fiber loopback cable can be classified according to fiber type used and fiber optic connector type. So we can find single-mode fiber loopback cable and multimode fiber loopback cable, as well as LC fiber loopback cable, SC fiber loopback cable and MTP/MPO fiber loopback cable on the market.

Application of Fiber Loopback Cable

Fiber loopback cable is often used to check whether fiber optic transceiver operates normally. As we all know, fiber optic transceiver has two ports, a transmitter port and a receiver port. During the testing process, the fiber loopback cable directly routes the laser signal from the transmitter port to the receiver port. Then we can compare the transmitted pattern with the received pattern to make sure the transceiver is identical and has no errors. Take MPO loopback cables for example, they are mainly used for testing parallel optics, such as 40G and 100G transceivers. In addition, the MPO fiber loopback assembly cable is available in 8 fibers, 12 fibers and 24 fibers, which can be applied according to different requirements of testing applications. To have a better understanding of fiber loopback cable's working way, here is a figure of fiber loopback cable used for testing application for you.

Conclusion

Fiber loopback cable is designed for equipment testing, self-testing, engineering, network diagnostics and measurement applications. It plays an important role in troubleshooting in laboratories and manufacturing environments. Besides, it provides a cost-effective way to test the transmission capability and receiver sensitivity of optical network equipment. When choosing a suitable type of fiber loopback cable, we should take the connector type, polish type, and cable type into consideration.