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Optical Transceiver Nomenclature

Optical transceivers come in many different formats. The most popular ones today would have to be SFP, SFP+, XFP, SFP28, QSFP+, and QSFP28. Have you ever wondered if these letters meant something or was it just another set of engineering alphabet soup without any particular significance?

As it turns out, not only do these acronyms stand for something but they also follow a technology evolution trend over the years. The first of these optical transceivers to hit the market in the early 2000s was the SFP which stands for Small Form-factor Pluggable. This type of transceiver typically will address transmission rates up to 1G. As transmission rates evolved towards 10G, the XFP optics soon followed. Here the X was used to indicate the ability to go up to 10G rates given that X is the Roman numeral for 10. Today though, the more common transceiver used for 10G is the SFP+. From a physical perspective, it looks very much like the SFP (which is smaller than XFP) so to differentiate the two nomenclature wise, the + was added to point to the fact that it is like an SFP in form factor but capable of transmission up to 10G rates.

If we now consider the SFP28 optics, these are once again very similar in dimensions to the SFP but they can handle transmission rates up to 25G. This is why the number 28 was added to the name. This is a reference to the transmission rate of the electrical lane feeding the transceiver which is 28G even though the transceiver is commonly referred to as a 25G transceiver.

Next we have the QSFP+ optical transceivers which are specifically for 40G transmission. Here the Q stands for Quad indicating that this transceiver has 4 electrical lanes instead of a single lane like the SFP, SFP+ or SFP28. As such, if SFP+ offers a single lane at 10G, then QSFP+ would provide 4 such lanes for a total of 40G bandwidth. Finally, the QSFP28 naming follows the same logic with the Q standing for Quad once again. However, here we have 4 electrical lanes each at 28G resulting in a total bandwidth of 112G though it is more commonly know as a 100G optical transceiver.

GigOptics - Your Trusted Supplier for Optical Transceivers

At Gigoptics, we offer a wide range of optical transceivers to meet the requirements of various application; all tested to ensure quality and reliability. For more information, contact us at

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