Focus On Fiber Optic Link Loss

We know that, no natter what component you use, there must insertion loss in your fiber optic cabling. Therefore, in order to make your fiber optic cabling system perform at high level, calculating the amount of insertion loss before cable plant is necessary. This article will focus on fiber optic link loss.

Overview of Link Loss And Link Loss Budget

The link loss and link loss budget are measured in dB. Link loss is the total insertion loss of all optical components in an optical network. While link loss budget is the amount of loss that a cable plant should have. It is calculated by adding the average losses of all the components used in the cable plant to get the total estimated end-to-end loss. The link loss budget has two important functions: during the design stage to ensure the cabling being designed will work with the links intended to be used over it and; after installation, comparing the calculated link loss to test results to ensure the cable plant is installed properly.

How to Calculate Link Loss?

Usually, the loss of four parts need to be calculated: mated pair connector loss, fiber optic splicing loss, fiber optic cable loss and other loss.

link loss calculation

  • Mated Pair Connector—EIA/TIA 568 standard allows 0.75 max per connector

Connector or “connection” loss is the total loss of the mated pair connectors. It’s standard to assume a 0.3 dB loss for most ultras polished connectors. In order to measure the loss of the connectors, you must mate them with similar connectors, or you are likely to experience different losses. Also, a high quality connector is required when testing matted pairs.

  • Fiber Optic Splicing—EIA/TIA 568 max loss is 0.3 dB per splice

According to the Fiber Optic Association (FOA), multimode splices are commonly made using mechanical splices. Best construction practices dictate that even with multimode fiber fusion splicing is ideal. Both forms of splicing generally result in satisfactory results, however fusion splicing proves to be more reliable in adverse surroundings. Single mode fibers that have been fusion spliced will typically have less than 0.10 dB loss. A good average for a skilled installer is generally around 0.05 dB loss.

  • Fiber Optic Cable

EIA/TIA 568 spec for multimode fiber is 3.5 dB/ km at 850 nm and 1 .5 dB/km at 1310 nm. This specification translates into a loss of approximately 0.1 dB per 100 feet for 850 nm, 0.046. dB per 100 feet for 1300 nm. For example, 300 ft multimode fiber optic cable at 850 nm would approximately equal 0.3 dB loss. While for single mode fiber, the loss is 0.5 dB per km at 1310 nm, 0.4 dB per km for 1550 nm.

  • Other Loss—Passive Components and Margin

Don’t forget to count any other passive components you are using in your network. For example, if you are using splitters or filters, add the insertion loss for those components. In addition, it is recommended to add margin to your link loss calculation to adjust for any unforeseen losses. The amount may vary by designer or application but typically 2-3 dB will allow for sufficient headroom in you network link loss calculation.

Conclusion

The fiber optic link loss calculation and analysis are vital in cable plant. After the cable plant is installed, the calculated loss values are compared with the test results to ensure the link can operate properly. Besides, to reduce the link loss, high quality components are required. Quality is everything when gigabit and higher speeds are required. FS.COM provides high quality fiber optic connector, fiber optic cable and fiber optic transceiver at reasonable price. Also, test tools can be found here, such as light source and power meter. For more details, you can visit our site.

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Overview of 100G Transceivers

There was a time when 10G to 40G migration was a hot spot, and as the only available 40G transceiver, 40G QSFP+ has occupied the major position in the market. However, the pace of development has never stopped and the demand for higher speed data transmission keeps growing. And now, many data center managers set their sight on 100G Ethernet. As an important component in 100G optical links, 100G transceivers gradually gain great popularity among data center managers. But unlike 40G transceiver, 100G transceiver has several types, such as CFP/CFP2/CFP4, CXP and QSFP28. How much do you know about them? This article is going to give an overview of 100G transceivers.

CFP/CFP2/CFP4

The letter “C” in CFP/CFP2/CFP4 stands for 100. The CFP transceiver is specified by MSA between competing manufacturers and it can support 100Gbps over both single-mode and multimode fiber. The electrical connection of a CFP uses 10 x 10G lanes in each direction (RX, TX) while the optical connection can support both 10 x 10G and 4 x 25G variants of 100G interconnects. With improvement in higher performance and higher density, CFP2 and CFP4 appeared. While electrical similar, they specify a form factor of 1/2 and 1/4 respectively in size of CFP. CFP, CFP2 and CFP4 modules are not interchangeable, but would be inter-operable at the optical interface with appropriate connectors.

CFP-CFP2-CFP4

Here is a table for you which shows five typical transceiver types. We can get that CFP-SR10-100G is structured with 24-fiber MTP connector interface, so it can be used with multimode MTP 24 to MTP 24 100g trunk cable to support 100G optical links over short distance; designed with LC duplex interface, CFP-LR4-100G, CFP-ER4-100G, CFP2-LR4-100G and CFP4-LR4-100G are used with LC duplex patch cable to support 100Gbps data rate over long distance.

CFP CFP2 CFP4 transceiver information

CXP

The CXP was created to satisfy the high-density requirements of the data center, targeting parallel interconnections for 12x QDR InfiniBand (120G), 100G, and proprietary links between systems collocated in the same facility. The CXP is 45 mm in length and 27 mm in width, making it slightly larger than an XFP. It includes 12 transmit and 12 receive channels in its compact package. This is achieved via a connector configuration similar to that of the CFP.

QSFP28

Similar to 40G QSFP+, 100G QSFP28 also offers four independent transmit and receiver channels, but each channel is capable of 25Gbps data rate for an aggregate data rate for 100Gbps. With an upgraded electrical interface to support signaling up to 25Gbps signals, the 100G QSFP28 makes it as easy to deploy 100G network as 10G networks. When compared to any of the other alternatives, the 100G QSFP28 increases density and decreases power and price per bit, but It has to noted that 100G QSFP28 has the same physical size as 40G QSFP+. Just like 40G QSFP+, 100G QSFP28 can be both deployed for short data transmission distance over multimode fiber and long data transmission distance over single mode fiber. For example, 100GBASE-PSM4 QSFP28 can be used with MTP single mode cable to support 100G data rate with link length up to 500 meters.

100G QSFP28 transceiveres

Conclusion

Now is the time of 100G Ethernet and 100G transceivers are indispensable to complete the 100G optical links. As there are various types of 100G transceivers available on the market, it is necessary to choose the best suitable one for your network deployment. As a professional manufacturer and supplier in optical communication industry, FS.COM provides a complete range of 100G transceivers to meet the potential requirements. The prices of all our 100G transceivers are much more affordable than the similar products in the market. Furthermore, with the mature coding technology, they can be compatible with many major brands. For more details, please visit our site.