10 Gigabit Ethernet (10GbE) is a group of computer networking technologies for transmitting Ethernet frames at a rate of 10 gigabits per second. There are several kinds of optical transceiver modules used for 10 Gigabit Ethernet. Small form-factor pluggable plus (SFP+) transceiver is one popular module type on 10GE systems due to its small size and low power. 10GbE SFP+ transceiver can be classified into many categories. 10GBASE-SR SFP+, 10GBASE-LR SFP+, 10GBASE-ER SFP+, and 10GBASE-LRM SFP+ are four common types among them. This post will give a brief introduction to them.
SR stands for short reach. 10GBASE-SR is the original multi-mode optics specification, and is still by far the most commonly used. SFP+ optical transceiver module for 10GBASE-SR uses 850nm laser to support 10GbE transmission over standard multi-mode fiber. 10GBASE-SR SFP+ supports up to 400 meters using the laser optimized OM4 multi-mode fiber. 10GBASE-SR transmitter is implemented with a VCSEL which is low cost and low power. 10GBASE-SR delivers the lowest cost, lowest power and smallest form factor optical modules. The following is a picture of Cisco ONS-SC+-10G-SR 10GBASE-SR SFP+ transceiver.
LR stands for long reach. 10GBASE-LR SFP+ is designed for single-mode fiber and operates at a wavelength of 1310nm. The 10GBASE-LR transmitter is implemented with a distributed feedback laser (DFB). DFB lasers are more expensive than VCSELs but their higher power and longer wavelength allow efficient coupling into the small core of single-mode fiber over greater distances. 10GBASE-LR can reach up to 10km over single-mode fiber. For example, Brocade 10G-SFPP-LR 10GBASE-LR SFP+ transceiver shown below uses a 1310nm multiple quantum DFB laser and transmits distance up to 10km.
ER stands for extended reach. 10GBASE-ER transmitter is implemented with an externally modulated laser (EML). 10GBASE-ER SFP+ is a port type for single-mode fiber and uses 1550nm lasers to support 10GbE transmission over single-mode fiber. This kind of SFP+ module is used to connect devices both in the same cabinet and in different physical locations up to 40km in distance that is widely used in large building, co-location facilities and carrier neutral internet exchanges.
LRM stands for long reach multi-mode. 10GBASE-LRM SFP+ modules use a single higher-speed laser operating at 10.310Gbit/s. This creates a simpler optical path, but requires more expensive components. The LRM laser can either be a distributed-feedback (DFB) laser, a vertical-cavity surface-emitting laser (VCSEL), or a Fabry-Perot (FP) laser. Both DFBs and VCSELs provide a very clean, single-wavelength output, which minimizes signal degradation due to spectral effects. On the other hand, an FP laser source produces a range of different wavelengths. Each of these wavelengths travels through the fiber at slightly different speeds, creating additional jitter that must be recovered by the EDC circuit at the receiver. While small, this added jitter could compromise operation on some fibers.
Different 10GbE fiber cabling technologies have different optical interface standards. Over the years of 10 Gigabit Ethernet ‘s existence, there have been numerous different form factors to meet different standards. XENPAK, X2, XFP and SFP+ are currently four popular kinds of modules in the market. Fiberstore provides a large variety of 10GbE optical modules branded by major brands, like Cisco, HP, Juniper, Brocade and Finisar. You can find all these types of optical transceiver modules for 10GbE with high quality from Fiberstore.