A Closer Look at 100G QSFP28 Single Lambda Modules for Modern Data Centers

100G QSFP28 optical module, as a mainstream solution for high-speed data center interconnects, has been widely adopted in various high-performance network environments. Compared to the traditional 4×25G solution, the 100G QSFP28 Single Lambda module offers a simpler design by transmitting 100Gbps over a single wavelength.This helps reduce deployment complexity and lower overall costs. At the same time, it meets the demands of high-speed interconnects, making it an ideal solution for next-generation data centers.

Overview of 100G QSFP28 Single Lambda optical modules

The 100G QSFP28 Single Lambda is an optical transceiver designed for data centers and high-speed networks, capable of delivering 100Gbps of data over a single wavelength. Based on PAM4 (4-level Pulse Amplitude Modulation) technology, it enables high-bandwidth transmission in a compact form factor and is typically used for short- to medium-distance connections.

Single Lambda technology refers to optical communication that achieves data rates of up to 100Gbps over a single optical channel (or wavelength). As an emerging optical module solution, it is widely adopted in high-speed Ethernet links such as 100G, 200G, and 400G, playing a crucial role in modern data centers and cloud computing environments.

In simple terms, traditional 100G optical modules—such as 100G QSFP28 SR4 or LR4—typically use a 4×25Gbps multi-channel design, achieving a total bandwidth of 100Gbps through four wavelengths or four fibers. In contrast, Single Lambda technology delivers the same 100Gbps data rate using just one wavelength (lambda), greatly simplifying the module architecture.

Core Technologies

PAM4 Modulation

PAM4 (Four-Level Pulse Amplitude Modulation) replaces traditional NRZ (Non-Return-to-Zero) binary modulation by encoding 2 bits per symbol instead of 1. This allows more data to be transmitted within the same bandwidth.

PAM4 is the key enabling technology for Single Lambda high-speed transmission. Compared to NRZ, which transmits one bit per symbol, PAM4 doubles the data rate, making it possible to achieve 100Gbps over a single wavelength. It is also the core modulation scheme used in next-generation 400G and 800G optical modules, forming the foundation of high-speed optical networks.

High-Speed Electro-Optical Components

Single Lambda modules require high-performance components such as lasers, modulators, and receivers that support 50Gbps or higher per lane. These components are critical for maintaining signal integrity at high data rates.

Advanced DSP (Digital Signal Processing)

Modern modules integrate advanced DSP technology to handle tasks like equalization, Forward Error Correction (FEC), and clock recovery. This ensures reliable performance and low bit error rates even under challenging high-speed transmission conditions.

100G QSFP28 Single Lambda Key Specifications

Types of 100G Single Lambda Module

According to relevant standards set by IEEE and MSA organizations, 100G QSFP28 Single Lambda optical modules are categorized into several subtypes, primarily distinguished by transmission distance, application scenarios, and technical implementation methods. Key products include: 100G QSFP28 DR, 100G QSFP28 FR,100G QSFP28 LR,100G QSFP28 ER，100G QSFP28 FR CWDM， 100G QSFP28 LR CWDM, 100G QSFP28 LR BIDI 10km/20km,100G QSFP28 ER Lite BIDI 30km, 100G QSFP28 ER BIDI 40km, and 100G DWDM QSFP28 ZR.

100G QSFP28 DR

The 100G QSFP28 DR transceiver uses single-wavelength PAM4 modulation to deliver up to 500 m transmission over single-mode fiber (SMF).The module incorporates one channel optical signal on 1310nm center wavelength, operating at 50Gbaud data rate. The module has a maximum power consumption of 3.5W. Featuring QSFP28 form factor and 100 GbE compliance, it offers low power consumption and stable performance, making it ideal for short- to medium-distance data center interconnects and cloud network upgrades.

100G QSFP28 FR

The 100G QSFP28 FR optical transceiver adopts the standard QSFP28 form factor and delivers 100Gbps Ethernet connectivity. Designed based on the IEEE 802.3cu 100GBASE-FR1 standard, it uses single-channel 1310nm technology to achieve reliable transmission up to 2 km over single-mode fiber. Compared with traditional multi-wavelength solutions, the FR1 single-channel design simplifies link architecture, reduces cost and power consumption, making it an ideal choice for data center interconnects (DCI), enterprise core networks, and other medium-distance, cost-effective 100G applications. It supports hot-pluggable operation for easy, plug-and-play deployment.

100G QSFP28 LR

100G QSFP28 LR Optical Transceiver delivers 100Gbps Ethernet connectivity compliant with the IEEE 802.3cu 100GBASE-LR1 standard. It adopts advanced single-lambda 1310nm technology to achieve reliable transmission over up to 10km on single-mode fiber. The LR1 single-wavelength design significantly simplifies network architecture, reducing system complexity and power consumption compared to traditional multi-channel solutions. Ideal for metro access, data center interconnect (DCI), and other medium-to-long-distance applications requiring a cost-effective 100G solution. Supports hot-pluggable design for easy deployment.

100G QSFP28 ER

The 100G QSFP28 ER optical transceiver adopts the QSFP28 form factor and supports 100Gbps Ethernet transmission. Based on PAM4 modulation technology and the IEEE 802.3cn 100GBASE-ER1 standard, it uses a single 1310nm wavelength channel over single-mode fiber to achieve ultra-long-distance transmission (ER1-30: 30km / ER1-40: 40km). This design significantly simplifies network architecture and provides a high-bandwidth-density solution, making it ideal for metropolitan backbone networks, long-haul data center interconnects (DCI), and 100G applications requiring distances beyond the 10km limit. It also supports Digital Diagnostics Monitoring (DDM) and hot-swappable operation.

Why Choose Single Lambda?

Compared with the traditional 4×25G approach, the 100G QSFP28 Single Lambda offers significant advantages:

Simplified architecture with fewer lasers

The 4×25G solution requires four parallel lasers and receiver channels, whereas Single Lambda achieves 100G transmission using only one laser and one receiver. This reduces component complexity, eases optical alignment, and enhances manufacturing consistency and reliability.

Lower power consumption and higher integration

Fewer components mean less driving circuitry and lower cooling requirements, resulting in reduced power consumption at the same data rate. The high level of integration also supports more compact module designs, ideal for high-density data center deployments.

Lower cost per bit

With fewer lasers, driver chips, and optical components, manufacturing costs are reduced. The simplified optical architecture also improves yield rates, further lowering the cost per transmitted bit.

Excellent compatibility with existing equipment

Single Lambda modules typically use standard QSFP28 form factors and interfaces, enabling seamless interoperability with existing switches and routers without major network redesign, minimizing upgrade complexity and cost.

Future Trends

As data centers and communication networks demand higher speeds, lower power consumption, and greater integration, 100G Single Lambda technology is evolving toward higher performance. Key trends include:

Evolution toward 400G and 800G

Single Lambda technology serves as the foundation for 400G and 800G optical modules. For example, 400G-FR4 uses a 4×100G PAM4 channel design, aggregating four 100G single-lambda channels to meet growing bandwidth needs. Higher-speed modules like 800G-LR also leverage single-wavelength high-speed transmission to support data center and backbone network upgrades.

Silicon Photonics (SiPh) Integration

Silicon photonics integrates optical components onto silicon chips, significantly reducing power consumption and cost while improving reliability and manufacturability. Leading vendors such as Intel and Cisco have introduced 100G and higher-speed modules based on SiPh technology, signaling a future of smaller, lower-power, and smarter optical modules.

Linear Pluggable Optics (LPO)

LPO technology eliminates complex digital signal processors (DSPs) to achieve ultra-low power consumption (<3W) in 100G Single Lambda modules. This approach is ideal for power-sensitive, high-density data center deployments, reducing cooling demands and energy costs.

Selection Recommendations

Choosing the right 100G QSFP28 Single Lambda module depends on specific application scenarios and requirements:

1.Short-Distance High-Density Interconnects

For high-speed interconnects within or between racks in data centers, 100G-DR modules (up to 500 meters, LC interface) are recommended. These modules offer low power consumption and compact size, perfect for large-scale high-density deployments.

2.5G Front-Haul and Medium-Distance Transmission

For 5G base station front-haul and campus networks, 100G-LR BiDi modules are preferred. Supporting single-fiber bidirectional transmission, these modules save fiber resources and reduce network deployment costs.

3.Future-Proof Upgrade Path

Given the rapid growth in network bandwidth and evolving technology, it is advisable to prioritize modules supporting PAM4 modulation and silicon photonics. Such modules offer higher data rate potential, better energy efficiency, and scalability for smooth upgrades to 400G and beyond.

As network bandwidth demands continue to rise, 100G QSFP28 Single Lambda technology stands out as an ideal choice for data centers and high-speed networks due to its simplified architecture, low power consumption, and cost-effectiveness. Moving forward, with the evolution toward 400G and higher speeds, Single Lambda will continue to play a crucial role in building more efficient and flexible network infrastructures.