SFP transceivers are commonly used and necessary in our daily life. And there are two kinds: single mode SFP and multi-mode SFP. However, maybe most people don’t know these two SFP transceivers are different. The following are the differences between single mode SFP and multi-mode SFP.
Diameter of the Core
Single mode SFP has a small diametral core that allows only one mode of light to propagate. Because of this, the number of light reflections created as the light passes through the core decreases, lowering attenuation and making the signal travel faster.
Compared with single mode SFP, multi-mode SFP has a larger diametral core that allows multiple modes of light to propagate. Thus when the light passes through the core, the number of light reflections increases, more data could pass through in a given time.
Single mode SFP are affected by waveguide dispersion caused by the light going down the fiber being wider than the core of the fiber. This allows more control of the path of the photons, but gets more influences from micro bends, twists, and stress on the fiber. So it’s often applied in long distance, higher bandwidth runs by Telcos, CATV companies, and Colleges and Universities.
Whereas multi-mode SFP are affected by Modal Dispersion, caused because the light rays follow different paths through the fiber and arrive at different times on the other end. Due to the high dispersion and attenuation rate with this type of fiber, the signal will become worse during its transmission over long distances. So multi-mode SFP could be typically used for short distance, data and audio/video applications in LANs. RF broadband signals, such as what cable companies commonly use, cannot be transmitted over multi-mode fiber.
Single mode SFP costs more than multi-mode SFP. Why does this happen? Because single mode SFP and multi-mode SFP use a different type of light emitting unit. Single mode SFP have fine laser i.e 1310nm or 1550nm. But multi-mode SFP having LED or lower wavelength type light emitting unit. Multi-mode couplers & lasers are a lot cheaper to manufacturer. Single-mode couplers & lasers are tuned & built to a much higher standard and cost a lot more to produce. So single mode SFP is always more expensive than multi-mode SFP.
The main purpose of showing these differences is for you to know SFP transceivers better and choose a suitable one. And the two transceivers are identified by colors on the outer jacket. The single mode SFP is yellow or blue, while the multi-mode SFP is orange or aqua.