For 100G optical transceivers, there are a number of form factors including CFP/CFP2/CFP4, CXP and QSFP28. Among these different 100G form factors, it appears that the market has chosen QSFP28 as the primary form factor for 100G links. Hence, this post will focus on several types of 100G QSFP28 transceivers—100GBASE-SR4 QSFP28 transceiver, 100GBASE-PSM4 QSFP28 transceiver, 100GBASE-LR4 QSFP28 transceiver, and 100GBASE-CWDM4 QSFP28 transceiver.
The 100GBASE-SR4 QSFP28 transceiver is a parallel 100G optical transceiver. It provides increased port density and total system cost savings. This 100G QSFP28 full-duplex optical transceiver offers 4 independent transmit and receive channels, each capable of 25 Gbps operation for an aggregate data rate of 100 Gbps on 100 meters over OM4 MMF. Generally, 100GBASE-SR4 QSFP28 transceiver converts parallel electrical input signals into parallel optical signals by a driven VCSEL array. The transmitter module accepts electrical input signals compatible with CML (common mode logic) levels. All input data signals are differential and internally terminated. The receiver module converts parallel optical input signals via a photo detector array into parallel electrical output signals. The receiver module outputs electrical signals are also voltage compatible with CML levels. All data signals are differential and support a data rates up to 25 Gbps per channel.
The 100GBASE-PSM4 QSFP28 transceiver is a parallel 100G single-mode optical transceiver with an MTP/MPO fiber ribbon connector. It uses 8 fibers (4 transmit and 4 receive), each transmitting at 25 Gbps, resulting in an aggregate data rate of 100 Gbps on 500 meters over SMF. The working principle of 100GBASE-PSM4 QSFP28 transceiver is nearly the same with the 100G QSFP28 SR4 transceiver. The only difference is that PSM4 works over SMF, while SR4 works over OM4 MMF.
The 100GBASE-LR4 QSFP28 transceiver converts 4 input channels of 25 Gbps electrical data to 4 channels of LAN WDM optical signals and then multiplexes them into a single channel for 100G optical transmission. On the receiver side, the module demultiplexes a 100G optical input into 4 channels of LAN WDM optical signals and then converts them to 4 output channels of electrical data. The central wavelengths of the 4 LAN WDM channels are 1295.56, 1300.05, 1304.58 and 1309.14 nm as members of the LAN WDM wavelength grid defined in IEEE 802.3ba. The 100GBASE-LR4 QSFP28 transceiver provides superior performance for 100G applications up to 10 km over SMF and compliant to optical interface with IEEE802.3ba 100GBASE-LR4 requirements.
The 100GBASE-CWDM4 QSFP28 transceiver is a full duplex 100G QSFP28 optical transceiver that provides a high-speed link at aggregated data rate of 100 Gbps over 2 km on SMF. The transmitter path converts four lanes of serial electrical data to optical signal. The optical signals from the four lasers are optically multiplexed and coupled to single-mode fiber through an industry standard LC optical connector. The optical signals are engineered to meet the CWDM4 MSA specifications. On the receive side, the four incoming wavelengths are separated by an optical demultiplexer into four separated channels.
This article has introduced the basic information about 100GBASE-SR4 QSFP28 transceiver, 100GBASE-PSM4 QSFP28 transceiver, 100GBASE-LR4 QSFP28 transceiver, and 100GBASE-CWDM4 QSFP28 transceiver. The following table summarizes the differences of these four types of 100G QSFP28 transceivers. You should first make clear each type and then choose the one that best suits your network demands. In addition to the generic ones mentioned in this post, we also have other 100G QSFP28 transceivers compatible with major brands such as Cisco, etc. For the detailed information, you can visit www.fs.com.
|Transceiver Type||Interface||Transmission Distance|
|100G SR4 QSFP28 Transceiver||MTP/MPO-12||100m over 8 MMFs|
|100GBASE-PSM4 QSFP28 Transceiver||MTP/MPO-12||500m over 8 SMFs|
|100G LR4 QSFP28 Transceiver||LC duplex||10km over 2 SMFs|
|100GBASE-CWDM4 QSFP28 Transceiver||LC duplex||2km over 2 SMFs|
Further reading: SFP28 vs. SFP+ vs. QSFP28