QSFP28 ER4 1310nm 100G 40km Optical Transceiver is a high-performance, long-reach solution for 100G networks. By leveraging 4x25G lanes, LAN-WDM multiplexing, and APD-based high-sensitivity receivers, it enables reliable 40-kilometer transmission over single-mode fiber. It is a critical component for building large-scale network backbones and implementing cost-effective, long-distance data center interconnects.

Key Features and Nomenclature Breakdown

●Form Factor: QSFP28

●QSFP: Quad Small Form-factor Pluggable.

●28: Indicates the maximum supported data rate per lane (here, 25.78 Gbps for carrying 100G signals). The QSFP28 is the dominant industry-standard form factor for 100G applications, offering high port density, low power consumption, and hot-pluggability.

●Data Rate: 100G

The transceiver provides an aggregate throughput of 100 Gbps. It utilizes an internal 4x25G architecture, where four independent lanes each operate at approximately 25.78 Gbps to multiplex into a single 100G stream.

●Reach: 40km (ER4)

●ER: Stands for Extended Reach.

●4: Denotes the use of four wavelength lanes (often associated with the 40km distance target).

This is a long-reach transceiver with a typical guaranteed transmission distance of 40 kilometers. It is suitable for metropolitan area networks, campus interconnects, and other scenarios requiring links beyond the reach of SR/LR modules.

●Wavelength & Technology: 1310nm LAN-WDM

It operates using four precise wavelengths in the 1310nm band (approximately 1295.56, 1300.05, 1304.58, and 1309.14 nm). This technology is called LAN-WDM (Local Area Network Wavelength Division Multiplexing).

The 1310nm window in single-mode fiber experiences relatively low chromatic dispersion, making it highly suitable for medium to long-haul transmission.

●Key Technology: To overcome signal attenuation over long distances, the receiver side of the module typically employs an APD (Avalanche Photodiode). APDs offer significantly higher sensitivity compared to standard PIN photodiodes, allowing them to detect much weaker optical signals.

●Fiber Type & Connector: Single-Mode Fiber, Dual LC Duplex

Must be used with Single-Mode Fiber (SMF).

The transceiver faceplate features two LC duplex ports. This is due to its "Bi-Directional" transmission scheme:

One port (with Tx and Rx) is used to transmit the multiplexed signal of four wavelengths.

The other port (with Tx and Rx) is used to receive the four-wavelength multiplexed signal from the far-end module.

Therefore, a total of two single-mode fiber strands are required for full-duplex 100G communication.

Primary Applications

●Data Center Interconnect (DCI): Connecting geographically separated data centers or campuses within a metropolitan area.

●Telecom Metropolitan Area Networks (MAN): For 100G links in aggregation or core network layers.

●Enterprise Network Backbone: Core connectivity for large enterprise or campus networks.

●100G Ethernet Switch Uplink Ports.

Comparison with Other Common 100G Transceivers

The QSFP28 ER4 is a high-speed optical transceiver module designed for 100 Gigabit Ethernet and data center interconnects. Its key feature is enabling transmission over single-mode fiber for distances of up to 40 kilometers.