QSFP+ and QSFP28 Product Portfolio

C-LIGHT, a Shenzhen-based professional high-end optical transmission module supplier founded in 2011, specializes in the development and production of active optical modules, optical passive devices, and data exchange equipment. The company offers a comprehensive range of QSFP+ and QSFP28 products designed for diverse networking environments, from enterprise data centers to telecom operator networks.

C-LIGHT QSFP+ (40G) Products

C-LIGHT‘s independently developed 40G QSFP+ optical modules cover an extensive range of transmission distances to meet varied deployment requiremens.

The 40G CWDM4 QSFP+ ER4 variant utilizes 4-channel CWDM wavelength multiplexing technology to support 40 Gbps data transmission over 40 km of single-mode fiber, making it suitable for extended-reach metro applications

For specialized high-speed storage applications, C-LIGHT also offers a 128G QSFP+ optical transceiver featuring a quad-channel parallel design, with each channel supporting 32 Gbps transmission for an aggregate bandwidth of 128 Gbps-.

C-LIGHT QSFP28 (100G) Products

C-LIGHT has constructed a comprehensive portfolio of 100G long-reach optical transceivers covering distances from 10 km to 140 km, with multiple variants optimized for different network requirements:

QSFP28 100G ER4: This module is specifically designed for long-distance, high-performance data communication and has become a critical component for achieving 40 km, 100 Gbps high-speed interconnection in metropolitan area networks (MANs)-19. It complies with established technical standards specifying the optical requirements for 100 Gbps transmission over single-mode fiber at distances up to 40 kilometers-19.

QSFP28 100GE/OTU4 Dual-Rate LR4: This module supports both 100 Gigabit Ethernet (103.1 Gb/s aggregate) and OTU4 (112 Gb/s aggregate) operation, offering flexibility for both data center and telecom transport applications. It features a hot-pluggable QSFP28 form factor with power dissipation under 3.5W-.

QSFP28 100G Single Lambda BiDi: This bidirectional transceiver enables 100G transmission over a single fiber using Tx1309nm and Rx1304nm wavelengths, reducing fiber infrastructure requirements by half compared to traditional duplex solutions-20.

C-LIGHT DWDM QSFP28 Solutions

Beyond standard CWDM/LAN-WDM optics, C-LIGHT also offers independently developed 100G/40G/25G DWDM QSFP28 and QSFP+ optical modules supporting long-distance transmission at 10 km and 40 km. These products include CDR (Clock and Data Recovery) support and are designed for high-performance DWDM transport applications-.

Compatibility and Quality Assurance

C-LIGHT optical modules are designed for broad compatibility with industry-standard networking equipment. The company‘s product portfolio spans 100G CFP/CFP2/CFP4/QSFP28 series products, 40G QSFP+ optical modules, 25G SFP28, 10G SFP+, and various other transceiver types, enabling seamless integration into multi-vendor network environments-22.

All C-LIGHT transceivers are hot-pluggable and compliant with relevant MSA standards, including SFF-8436, SFF-8636, and QSFP28 MSA specifications, ensuring reliable operation across a wide range of switches and routers-.

Future Outlook: Beyond QSFP28

The QSFP form factor continues to evolve to meet ever-increasing bandwidth demands. QSFP56 represents the next step, using PAM4 modulation to achieve 50 Gbps per lane for a total of 200 Gbps, doubling the speed of QSFP28 while maintaining physical compatibility. QSFP-DD (Double Density) further expands capacity to 400 Gbps by doubling the number of electrical lanes to eight while preserving backward compatibility with QSFP28 modules in QSFP-DD cages.

Importantly, both QSFP56 and QSFP-DD maintain backward compatibility with QSFP28, meaning that organizations investing in QSFP28 infrastructure today can seamlessly transition to higher speeds in the future without wholesale equipment replacement. The QSFP-DD form factor supports 400G network transmission via 8×50G PAM4 lanes, making it the standard for hyperscale data center interconnections and AI/ML clusters

Conclusion

QSFP+ and QSFP28 represent two important milestones in the evolution of high-density optical transceivers. QSFP+ provides a proven, cost-effective solution for 40G connectivity in enterprise aggregation layers and moderate-bandwidth data center applications. QSFP28 delivers 100G performance in the same compact form factor, making it the industry standard for spine-leaf data center architectures, DCI, and high-performance computing environments.

The choice between QSFP+ and QSFP28 should be guided by bandwidth requirements, existing infrastructure, power and thermal constraints, and future growth projections. With QSFP28 ports being backward-compatible with QSFP+ modules, organizations can adopt a phased migration strategy that maximizes return on existing investments while preparing for higher-speed networking.

C-LIGHT offers a comprehensive portfolio of both QSFP+ and QSFP28 optical modules, spanning transmission distances from 100 meters to 140 kilometers and supporting a wide range of network protocols and fiber types. With products designed for enterprise data centers, telecom operators, and specialized high-speed applications, C-LIGHT provides flexible, standards-compliant optical connectivity solutions that address the evolving needs of modern networks.