Adding more fiber optic cable in the existed fiber optic network is a time and money consuming method to increase the transmission capacity of the network. In most cases, server providers cannot provide that much money and customers do not want to wait that long. To increase the fiber optic network capacity, BiDi fiber optic modules are being suggested for a variety of situations, which can support duplex transmission over a single strand of optical fiber. Now there are a lot of fiber optic transceivers designated with BiDi technologies to increase the network capacity. This post will introduce the most commonly used BiDi modules.
Generally, most fiber optic transceivers use two fibers for duplex transmission. However, most BiDi fiber transceivers use two different wavelengths to carry the duplex signals separately. In simple, the two wavelengths are just like two fibers. The optical signals for transmission and receiving are separately converted into signals of specific wavelengths. This is why most BiDi transceivers can support duplex transmission over a single fiber. The following picture shows the basic working principle of a BiDi transceiver.
Generally, BiDi transceivers can be divided according to the data rate and package form factors. Currently, the most commonly used BiDi fiber modules can support a data rate ranging from 1G to 40G, and are available in diverse form factor like SFP, SFP+ and QSFP+.
1G BiDi SFP (1000BASE-BX SFP)
For 1G BiDi transceiver, 1G BiDi SFP, also known as 1000BASE-BX SFP modules are often used in today’s network. One thing should be noticed before using BiDi modules, is that the BiDi modules should be used in pairs. As mentioned that BiDi modules use two different wavelengths for transmission. For instance, on one side of you use a BiDi SFP (Tx1310nm/Rx1490nm), on the other side a BiDi fiber SFP using 1490 nm for transmission and 1310 nm for receiving is required. A length of simplex single-mode LC to LC fiber cable is usually used to connect this pair of BiDi SFP module to achieve the connection.
10G BiDi SFP+ (10GBASE-BX SFP+)
10G BiDi SFP+ modules also have a simplex LC interface, which is also used in pairs and connected by simplex LC fiber cable. Generally, BiDi fiber transceiver can support a long transmission distance. To select the right 10GBASE-BX SFP+ module, wavelength and transmission distance are two important factors to be considered. Currently, 10G BiDi SFP+ modules using 1270nm and 1330 nm for transmission are most commonly used for 10G transmission. 10GBASE-BX SFP+ modules that support transmission distances of 10km, 20km, 40km and 80km are more popular according to statistic from FS.COM. Cisco compatible 10GBASE-BX20-D/U SFP+ and 10GBASE-BX10-D/U SFP+ are the most popular among all the third party 10G BiDi SFP+ modules.
There are also 10GBASE-BX SFP+ modules in other form factors, like 10G BiDi X2 (10GBASE-BX X2) modules. However, these modules are gradually exiting the market with the upgrading of the devices.
40G BiDi QSFP+ (QSFP-40G-SR-BD)
Unlike other BiDi fiber transceiver like 1000BASE-BX SFP and 10GBASE-BX SFP+, QSFP-40G-SR-BD module has a duplex LC interface. It uses BiDi technologies to achieve four strands of 10G optical signals over a duplex multimode LC fiber patch cable over two different wavelengths. My article (Using 10G Infrastructure for 40G Ethernet With 40G BiDi Optics) has introduced this module in details. The following shows the basic working principle of QSFP-40G-SR-BD. This module can achieve transmission distance up to 150 meters over OM4, 100 meters over OM3 and 30 meters over OM2.
Using BiDi fiber modules to increase the capacity of the existing fiber optic network is more effective in both time and money than adding more optical cables. Selecting the right BiDi modules should not only consider the data rate, transmission distance, package form factors, and wavelengths, price and quality are also essential factors. If quality and price are your priorities, then FS.COM is the right place to be. Kindly contact sales@fs.com or visit Fiber Optic Transceiver page of FS.COM for more details.
