Small Form-factor Pluggable Modules

Small form-factor pluggable is the full name of SFP, a prevailing type of fiber optic transceivers in the market. The transceiver can be simply regarded as the upgraded version of the GBIC module. SFP module is the half size of GBIC, but the numbers of ports configured on the same panels are double. Because the small-factor pluggable transceiver is the same function with GBIC, SFP transceivers is also called as mini-GBIC.
By placing the CDR and electrical dispersion compensation outside the modules, SFP transceiver modules greatly compressed the size and power consumptions.
Google currently are purchasing a large amount of SFP + modules to design and produce its own Gigabit Ethernet switches to meet the needs of the data center database system.
SFP Standard
SFP transceiver is regulated by a competition the Multilateral Agreement (MSA) between the manufacturers. The SFP is designed according to GBIC interface, allowing ratio the GBIC greater port density (the motherboard edge of the number of transceivers per inch), the SFP is also known as "mini-GBICs”. Compared with this small package transceivers (SFF transceiver), which is smaller than the SFP, but the SFF is soldered to the motherboard as a pin through-hole device, but not plugged into the edge.
SFP Type
SFP transceivers have a variety of different transmission and receiving type, the user can select the appropriate transceiver for each link, to provide the optical performance can be achieved based on the available fiber type (such as a multimode fiber or single mode fiber). Optical SFP modules available are generally divided into the following categories:
10 km distance of the wavelength of 850 nm / 550 meters distance MMF (SX)
1310 nm wavelength SMF (LX)
1550 nm wavelength / 40 km distance XD
80 miles from ZX
120 km distance from the EX or EZX
DWDM
SFP transceiver also have copper interface, making the host device designed primarily for fiber optic communication can communicate through the UTP network cable. There are also WDM (CWDM) and single fiber bi-directional "(1310/1490 nm wavelength uplink / downlink), SFP. Commercial SFP transceivers can provide a rate of 4.25 G bps. Several packages of 10 Gbps transceivers are XFP, SFP+, the updated version of SFP.