There are two types of SFP transceivers, Single-mode SFP and Multi-mode SFP, both work with a different kind of optical fiber. The Single-mode (also known as Mono-mode) fibers are used with Single-mode SFP transceivers, whereas Multi-mode optical fibers are used with Multi-mode SFP transceivers. Let’s discuss the difference between both and what should we take care of when using them.

What are Single-mode SFP transceivers?

The Single-mode fiber (SMF) has much close-fitted receptions for optics used. The core of this type of fiber is much smaller (around 9 µm) and the transmitted laser wavelength is narrower. This allows Single-mode fiber the ability for much higher bandwidth and for much longer distances in transmission. Single-mode SFP transceivers work mostly in 1310nm and 1550nm wavelength and are typically used in longer transmission distances, reaching 2km to 160km. Two Single-mode fibers are used for the transmission, one for transmitting and the other one for receiving the optical signal from the SFP. There are also Single-mode Bidi SFPs with Simplex connection available which are used in pairs, if 1310 nm is transmitted and 1550 nm is receiving wavelength at one end, then the other SFP must be transmitting at 1550 nm and receiving at 1310 nm. With Bidi SFPs this is made possible via WDM technique, which allows transmitting and receiving over only one single fiber.

What are Multi-mode SFP transceivers?

The Multi-mode fiber (MMF) has a much bigger core (50µm) and typically uses a longer wavelength of light. Due to this, the optics used with Multi-mode fiber have a greater ability to accept light from the laser. The optics used with Multi-mode fiber are cheaper compared to the ones used with Single-mode fiber. The common Multi-mode SFPs operate over 850 nm wavelength and are only used for short distance transmissions from usually about 100m to 550m. Although Multi-mode fiber is not capable to carry signals for a longer distance, in combination with multi-mode transceivers it is the cheapest solution for short distances.

Since these both types of fibers, Single-mode and Multi-mode are not compatible with each other. One of the main reasons for an incompatibility can be the choosing of a wrong wavelength and thus a wrong laser source, what leads to the fact that the fiber has the wrong core size and thus a data transmission does not come to pass.

While selecting the right SFP module, we must check the transmission distance and wavelength we want to use. This will help us to select the accurate SFP modules more efficiently. Furthermore, the costs for transceiver modules which keep adding up over time will be a problem for many users. To save even more, we can choose BlueOptics transceiver modules, containing compatible types of SFP, SFP+, XFP, QSFP and QSFP28 modules, which are a lot cheaper than artificially overpriced originals, which use the same components. BlueOptics offers fiber optic transceiver modules for any brand, such as Cisco, HPE, Juniper, Brocade, etc. which are all 100% compatible!