SWDM stands for Short Wavelength Division Multiplexing and is a new multi-vendor technology that promises to provide the lowest total cost solution for enterprise data centers to upgrade existing 10G duplex OM3/OM4 MMF infrastructure to 40G and 100G Ethernet；

This approach consists of multiple vertical cavity surface emitting lasers (VCSELs) operating at different wavelengths in the 850nm window (MMF optimized). A four wavelength implementation of SWDM is called SWDM4, these four wavelengths (850, 880, 910 and 940nm) are multiplexed/demultiplexed into a pair of MMFs inside the transceiver module (one fiber in each direction, i.e. standard duplex interface) . Each of the four wavelengths operates at 10G or 25G, enabling the transmission of 40G (4 x 10G) or 100G (4 x 25G) Ethernet over existing duplex MMFs using standard LC connectors.

The 100G SWDM4 transceiver is a 100G transceiver using SWDM4 technology. It provides 100Gbps bandwidth over standard duplex MMF without the need for expensive parallel MMF infrastructure. It provides a seamless migration path from duplex 10G to 100G.

According to the 100G SWDM4 MSA specification, the 100G SWDM4 QSFP28 transceiver can be used for links up to 75m of OM3 fiber or up to 100m of OM4 fiber. The Tx port transmits 100G data via 4 x 25Gbps wavelengths, and the Rx port receives data via 4 x 25Gbps wavelengths. The wavelengths are in the "short wavelength" range (from 850nm to 940nm)

Advantages of 100G SWDM4 Transceivers

1st Cost-effective: It uses two fibers (duplex) instead of eight (SR4), resulting in significant savings in fiber infrastructure capital expenditures.
2nd OM4 Support: It supports OM4 MMF with only two fibers.
3rd Easy migration to 100G: It enables seamless migration from 10G and 40G to 100G without major changes to the fiber infrastructure.
The widely deployed 10G-SR, 40G-BiDi and 40G-Universal optics all operate over a pair of MMFs with conventional LC terminations. The same goes for 100G-SWDM4 transceivers. Therefore, users do not need to change existing wiring or re-terminate.