What Is A 100G Single Lambda Optical Transceiver?

100G rate optical modules like 100GBASE-LR4, 100G-CWDM4, 100G-PSM4, and 100GBASE-SR4 are already quite popular in the market. However, in order to further reduce cost and improve transmission efficiency, the industry has proposed a standard for 100G single lambda optical modules. Today, we will discuss 100G single lambda optical modules in depth from several perspectives, including definition, comparison with common 100G QSFP28 modules, performance and future development trends.

What Is The 100G Single Lambda Optical Module?

100G Single Lambda 100G optical modules use PAM4 signaling technology to transmit 100G data on a single wavelength, as developed by the 100G Lambda MSA Alliance. At its core is a transmission rate of 100Gb/s per channel, with the goal of providing a more cost-effective solution for switching, routing, and high-density transmission at the multi-T level. The optical architecture of this module is much simplified compared to conventional multi-wavelength designs, with each wavelength capable of supporting 100G transmission, reducing component complexity and ultimately bringing costs down.

Introduction of 100G QSFP28 Single Lambda Module

100G QSFP28 DR

The 100GBASE-DR module is compliant with the IEEE 100GBASE-DR standard for single-mode fiber and supports 500-meter transmission, making it particularly suitable for data center leaf-ridge architecture connectivity. According to the QSFP28 MSA specification, it also features digital diagnostics on the I2C interface for real-time monitoring of operational parameters.

100G QSFP28 FR

The 100GBASE-FR module is compliant with the 100GBASE-FR1 standard and uses a 1310nm EML laser and PIN receiver to support 4x 25G NRZ electrical signals at a total rate of 100G, making it suitable for short-haul single-mode fiber transmission.

100G QSFP28 LR

Designed to support 100G Ethernet applications, the 100GBASE-LR module is suitable for single-mode fiber connections up to 10km and is a good choice for data centers, inter-building or transmission networks. It is backward compatible with 100G LR4 10km links and is compliant with the QSFP28 MSA, IEEE 802.3cd 100GBASE-LR1 and 100G Lambda MSA standards, making it suitable for use in core and aggregated network applications.

Differences And Advantages of 100G Single Lambda vs. Conventional 100G QSFP28

Simpler Architecture

100G single lambda optical modules usually include several types of 100G DR, 100G FR, 100G ER and 100G LR. After receiving 4x 25G electrical signals from the host, it converts the signals to PAM4 format through DSP and then sends the entire 100G traffic through a single laser. Compared to conventional 100G QSFP28 modules, single lambda modules do not require the use of WDM or parallel fiber, and the number of components is reduced accordingly, shrinking four transmitters and receivers to one.

Support for Longer Transmission Distances

For example, the 100G QSFP28 DR module max transmission distance is up to  500 meters, while the 100GBASE-FR module introduced by 100G Lambda MSA extends to 2 kilometers, which is useful for scenarios that require long-distance connectivity, such as certain high-loss network environments. MSA has also introduced the 100GBASE-LR with a transmission distance of up to 10 kilometers, similar to the 100G QSFP28 LR4 module.

Lower Cost

The single lambda design not only simplifies components, but also significantly reduces the cost of 100G links. According to IEEE research, a single lambda 100G solution can reduce the cost of a 100G optical link by at least 40 percent because the wavelengths for optical routing are reduced from four to one. This architectural optimization results in a significant reduction in overall cost.

How Can 100G Single Lambda Technology Drive The Acceleration of 400G?

Nowadays, the network demand becomes bigger and bigger, and the surge of data traffic makes the market have higher expectations for simplified and cost-reduced optical modules, especially in applications requiring high bandwidth and ultra-high density like 200G and 400G. The emergence of 100G single Lambda modules not only makes the upgrade of 100G networks to 400G smoother, but also simplifies the internal design of the 400G modules, which provides more technical support for 400G high-speed network expansion based on 100G Ethernet. 100G Ethernet-based 400G high-speed network expansion provides stronger technical support. Moreover, since this solution reduces the requirement for the number of optical fibers, it naturally reduces the overall cost.

Upgrade Path from 100G QSFP28 to 400G QSFP-DD

By introducing PAM4 modulation technology, single lambda 100G becomes a reality, making the upgrade from 100G to 4x100G more feasible. Taking the IEEE standard as an example, it uses 100GBASE-DR as the basis for 400GBASE-DR4. 400GBASE-DR4 can be split into four 100GBASE-DR modules to fulfill 400G connectivity requirements over a distance of 500 meters. In this way, the 100G single Lambda transceiver allows 400G ports to be connected with an easier 100G split.

100G Single Lambda Makes 400G Modules More Cost-Effective

The 100G Lambda MSA Consortium is also helping to upgrade the IEEE's 400G standard. The current 400G standard typically relies on eight 50G PAM4 signaling channels using a LAN-WDM wavelength mesh. However, this solution, like 100GBASE-LR4, suffers from a high number of wavelength channels, complex multiplexing and demultiplexing equipment, and high costs. To improve this situation, the 100G Lambda MSA proposes a single wavelength 100G solution using a 4-channel CWDM wavelength grid, which has greater fault tolerance and substantially reduces the overall cost of 400G.

Conclusion

Driven by the 100G Lambda MSA, 100G single lambda technology provides a more cost-effective option for building 100G Ethernet while accelerating the pace of network upgrades from 100G to 400G. Compared with traditional 100G QSFP28 modules, 100G single-wavelength optical modules excel in terms of transmission distance and cost. This shows that 100G single-wavelength is likely to become the first choice for more users in future 100G and 400G networks.