With the rapid growth of cloud computing, AI applications, and high-performance data centers, network bandwidth requirements have increased dramatically in recent years. To meet these demands, 100G optical connectivity has become a core component of modern network infrastructure. Among the various available solutions, 100G QSFP28 modules play a crucial role in enabling high-speed and long-distance data transmission. These transceivers provide reliable 100Gbps connectivity for switches, routers, and servers, making them essential building blocks in enterprise and data center networks.
One of the most widely used types of 100G QSFP28 modules is the 100GBASE-LR4 optical transceiver. Designed to support transmission distances of up to 10 kilometers over single-mode fiber, the 100G LR4 module uses LC duplex connectors and operates around the 1310nm wavelength band. This combination of long reach, stable performance, and compatibility with existing infrastructure has made LR4 transceivers a preferred option for data center interconnects and campus backbone networks.
Understanding the Role of Wavelength in Optical Transmission
Why Wavelength Matters in Optical Networks
In fiber optic communication, wavelength plays a critical role in determining transmission performance, distance capability, and signal stability. Different wavelengths behave differently when traveling through optical fiber. They experience varying levels of attenuation, dispersion, and interference, all of which directly affect the quality and reach of the transmitted signal. Selecting the appropriate wavelength is therefore one of the most important design considerations for any optical transceiver.
For 100G QSFP28 LR4 modules, the 1310nm band has been selected as the optimal operating wavelength. This is not an arbitrary choice but the result of decades of research and practical experience in optical networking. The 1310nm wavelength offers an excellent balance between performance, cost, and compatibility with existing fiber infrastructure, making it ideal for medium- to long-distance data transmission.
The Optical Characteristics of 1310nm
Single-mode fiber is optimized to transmit light efficiently at specific wavelength windows, primarily around 1310nm and 1550nm. Among these, the 1310nm region is known as the zero-dispersion window. At this wavelength, chromatic dispersion—the spreading of optical pulses over distance—is minimal. This characteristic is extremely important for high-speed transmission such as 100G, where signal integrity must be carefully maintained.
Lower dispersion means that signals can travel longer distances without requiring complex compensation mechanisms. For 100G LR4 transceivers, which transmit four parallel optical lanes at 25Gbps each, maintaining signal clarity is essential. The use of the 1310nm wavelength significantly reduces the risk of signal distortion and ensures stable performance across the full 10km transmission range.
1310nm and the Design of 100GBASE-LR4 Technology
How 1310nm Enables WDM Transmission
The 100G LR4 transceiver does not rely on a single optical channel. Instead, it uses wavelength division multiplexing (WDM) technology to combine four separate 25Gbps optical signals into one fiber pair. These four channels operate at closely spaced wavelengths around the 1310nm region, typically 1295nm, 1300nm, 1305nm, and 1310nm. This design allows a total aggregated bandwidth of 100Gbps to be transmitted over standard duplex single-mode fiber.
The 1310nm band is particularly suitable for this WDM architecture because it supports tight channel spacing while maintaining low interference between wavelengths. In addition, optical components such as lasers, multiplexers, and photodetectors are mature and highly optimized for this wavelength range, further improving the overall reliability and efficiency of LR4 modules.
Compatibility with Single-Mode Fiber Infrastructure
Another major advantage of the 1310nm wavelength is its excellent compatibility with existing single-mode fiber networks. Most enterprise campuses, metropolitan area networks, and data center interconnects already rely on OS2 single-mode fiber, which is designed to operate efficiently at 1310nm. By using this wavelength, 100G LR4 modules can be deployed without requiring any changes to cabling infrastructure.
This backward compatibility greatly simplifies network upgrades from 10G or 40G to 100G. Organizations can reuse their current fiber links while achieving significantly higher bandwidth. As a result, the 1310nm-based 100G LR4 solution provides a cost-effective and practical migration path for growing network demands.
Performance and Reliability Benefits of 1310nm
Lower Attenuation for Stable Long-Distance Transmission
Optical signal attenuation is another critical factor in transceiver design. Although the 1550nm wavelength offers slightly lower attenuation in theory, the 1310nm band provides a better overall balance when considering dispersion and system complexity. For distances up to 10km, which is the target range of 100G LR4 modules, 1310nm delivers more than sufficient performance with minimal signal loss.
The combination of low attenuation and low dispersion allows 100G LR4 transceivers to achieve stable and predictable link performance. This stability is especially important in data center interconnect applications, where even minor transmission errors can lead to packet loss or network downtime.
Support for Digital Diagnostic Monitoring
Modern 100G QSFP28 LR4 modules include Digital Diagnostic Monitoring (DDM) functions that allow real-time tracking of parameters such as temperature, optical power, and voltage. The stable optical characteristics of the 1310nm wavelength make these monitoring features more accurate and reliable. Network operators can easily evaluate link health and detect potential issues before they impact performance.
Conclusion
The 1310nm wavelength is a fundamental element behind the success of 100GBASE-LR4 QSFP28 optical transceivers. Its low dispersion, strong compatibility with single-mode fiber, and suitability for WDM technology make it the ideal choice for 10km high-speed transmission. By leveraging the advantages of this wavelength, 100G LR4 modules are able to deliver high bandwidth, excellent signal integrity, and cost-effective deployment.
As networks continue to evolve toward higher speeds and longer distances, the importance of selecting the right wavelength will remain critical. The widespread adoption of 1310nm in 100G LR4 transceivers clearly demonstrates its long-term value and relevance in modern optical communication systems. For organizations planning reliable and scalable 100G networks, understanding the role of the 1310nm wavelength is key to making informed deployment decisions.