Optical Transceiver Types: Use Cases, Compatibility & Buying Tips

Ever stood in front of a switch rack with a box of optics and thought, “Wait… is this the right one?” You’re not alone.

Cable type, distance, speed, form-factor, connector, and vendor compatibility — these are just a few of the critical factors that determine which transceiver or cable you actually need. Choosing the right optical transceiver isn’t as simple as grabbing the first one that fits. In fact, transceiver use cases are often one-to-one — meaning only a specific module will work based on your environment.

Take Cisco, for example. There are 17 different 10G SFP+ models. But if you need a short-range, multi-mode, 10G optic with LC ports, you’re probably looking for the SFP-10G-SR.

Whether you’re building out a data center, upgrading enterprise core switches, or just learning the ropes, this guide walks you through the world of optical transceivers — from 1G to 800G. We’ll break down the different types (SFP, QSFP, OSFP), what they’re used for, how to avoid compatibility headaches, and where AOCs and DACs fit into the picture.

And yes — we’ll help you find exactly what you need, without overpaying for OEM optics.

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👉 Use the Optics Finder Tool →

What is an Optical Transceiver and Why Choosing the Right One Matters

Before diving into form factors and protocols, let’s start with the basics: what is an optical transceiver?

Optical transceivers are hardware components that send and receive data over fiber optic cabling by converting electrical signals into light pulses, and then back again to electrical signals on the other side.

Compared to copper media, Fiber optic cabling can transport data over much longer distances, at much higher speeds, is about half the diameter, and is immune to electrical interference.

Here’s a quick size comparison of SFP and QSFP modules next to a 2.5" hard drive:

Why OEM Optic Modules Often Cost More Than the Hardware

If you’ve been doing this a while, you know that optics are more than just a line item in the Bill of Materials (BOM).  At OEM pricing, the cost of the transceivers can cost more than the platforms themselves.  It's why Gartner Research labeled OEM Optics as “The Biggest Rip Off in Networking.”

Take it from one of our customers — a national logistics company — they saved $2.1 million upgrading just seven facilities to 10G with Edgeium optics. That’s a significant amount of money that will stand up 2-3 other projects for the customer. And the $2.1M savings was for a client who receives a 68% standard channel discount.

No issues. No CLI workarounds. Just instant plug-and-play.

The Difference Between Single-mode and Multi-mode Fibers

This is where our journey begins!  What fiber you put in the walls will dictate what type of fiber module you will need.  You can use the cable plant that you can see to determine whether a cable run is single-mode or multi-mode.  

Basically, if it's yellow, it's single-mode.  If it's any other color, it's multi-mode.  As for the type of multi-mode, most vendors are standardizing on the following:

Common types of multi-mode fiber include:

• OM1 – Orange
• OM2 – Orange
• OM3 – Aqua
• OM4 – Pink
• OM5 – Green
• OS2 (single-mode) – Yellow

Single-mode fibers have a small core (<10 µm) allowing just one mode of light, ideal for long distances. Multi-mode fibers allow multiple light modes but are more limited in range.

You can't mix and match. If you have single-mode cabling, you need single-mode optics.

Real World Example

We once won a new customer because we shipped transceivers overnight — with Saturday delivery. The client, a healthcare provider, was racing to bring a new site online, and delays weren’t an option. His words? “This is about to become a medical emergency — for me.”

Edgeium came through, and the site went live on time.

📦 Need last-minute gear? We stock nearly $50M in inventory, ready to ship fast — even on weekends. Request a Quote and we'll help you look like a hero!

The difference in performance between single-mode and multi-mode fibers is primarily distance, although power draw can be included.  This assumes we’re not comparing OM1 With OS2.  OM1, OM2, and even now OM3 are relatively old.  

Single-mode fiber allows much further distances as a single mode can easily be more concentrated.  So, why not use all single-mode fiber and avoid any gotchas with distance?  Cost.  Single-mode components are significantly more expensive than their multi-mode counterparts.

*screenshots taken from www.cdw.com on 6/3/2025

Understanding SFP, QSFP & Other Optical Transceiver Types

Let’s break down the most common types of optics you’ll run into — what they are, what they’re used for, and how to know which ones you need.

There are two main form factors:

• SFP Family: SFP, SFP+, SFP28, SFP56
• QSFP Family: QSFP+, QSFP28, QSFP56, QSFP-DD, OSFP

Each header below includes a basic use case and real-world applications. You’ll find these transceivers (and more) in Edgeium’s Optics Finder.

Generally:

• Multi-mode optical fiber is most cost-effective up to the 500-600 meters range.
• Beyond that, single-mode optical fiber is required.

Types of Optical Transceivers

There are 10 primary versions of the SFP and QSFP form-factors that allow different transmission speeds, and there are various models within each of those categories as well that offer varying connectors, distances, media, etc.

1. SFP
2. SFP+
3. SFP28
4. SFP56
5. QSFP+
6. QSFP28
7. QSFP56
8. QSFP112
9. QSFP-DD
10. OSFP

SFP  100mb and 1Gbps transmissions over ethernet, as well as 2G and 4G over Fibre Channel. These modules offer RJ-45 or LC connectors and transmits/receives over a single channel. There are 9 different options differing by distance, media, and 2 that use the fiber strands differently (channel, lane, and path are used interchangeably).

A quick note on the BiDi and CWDM parts. Both of these use a technology known as Wavelength Division Multiplexing (WDM). WDM allows the transceiver to transmit and receive 2 different wavelengths in opposing directions over 1 fiber effectively doubling the throughput capacity of the transceiver. A 10Gbps WDM transceiver allows 20Gbps of transmission.

SFP+ This is an “enhanced” version of the SFP that supports data rates of 10Gbps, as well as 4G, 8G, and 16G over Fibre Channel.  The SFP+ also communicates over a single lane and utilizes LC or RJ-45 connectors.

SFP28  Also the same physical characteristics as the SFP and SFP+, but with an upgraded electrical interface that can handle 25Gbps per lane over ethernet and 32Gbps over Fibre Channel.  All SFP28 transceivers utilize LC connectors.

SFP56 Again, same physical chassis of SFP, but uses PAM4 modulation, and is designed for 50Gbps and 100Gbps connections.  While SFP56 are currently only available with LC connectors, look for SFP56 to push copper to 50Gbps! 

Modulation is the process of converting data into radio waves. After the light signal is generated, it needs to be modulated, or packaged, with the electrical data signal.

QSFP+  The “Quad” Small Form-Factor Pluggable (QSFP) introduces 4 channels over a single fiber in a slightly larger form-factor.to allow 4x 10Gbps transmission totaling a 40Gbps throughput.  The QSFP+ also introduces MPO and MPT connection options.  MPO/MPT are capable of bundling multiple fibers in a single connector to support greater throughput.

QSFP28 The QSFP28 simply added 4 channels using the SFP28 technology allowing 4x 25Gbps per channel to total 100Gbps throughput capability.

QSFP56 - The QSFP56 is a slightly more complex improvement of the QSFP28 and was designed to support 200Gbps of throughput. The primary change is the modulation technology which uses PAM-4 rather than NRZ. Without going too much into the details, just think of NRZ as having a maximum transmission value of 25Gbps where PAM-4 allows 50Gbps. Rather than 4x25Gbps in the QSFP28, the QSFP56 transmits over 4 independent channels at 50Gbps totaling 200Gbps throughput. 

Modulation is the process of converting data into radio waves. After the light signal is generated, it needs to be modulated, or packaged, with the electrical data signal.

QSFP112 The QSFP112 pushes throughput capability to 400G. Uses 4 optical pairs, each channel operates at 50Gbps PAM4, resulting in a total of 8 fibers (4x TX and 4x RX). These transceivers can be used to connect a single 400G connection, or break out to 4x100G with a compatible cable.

QSFP-DD The QSFP-DD brings “double density” to the party. The QSFP-DD is built with an additional row of contacts allowing 4 channels of high-speed transmission up to 100Gbps totaling 400G throughput capability.

OSFP The OSFP or Optical Small Form-factor Pluggable doubles the capacity of the QSFP-DD. This transceiver has 8 channels for transmission each capable of 100Gbps totaling 800Gbps throughput capability with development of 200Gbps channels in the works totaling 1.6TB.  Some OSFP modules allow a "breakout mode" which enables the transceiver to connect with multiple lower bandwidth applications including QSFP-DD, QSFP56, QSFP28, and even some SFP28 and SFP+ form factors.