25G SFP28 DWDM 20km optical transceiver is a high-performance optical transceiver designed for 5G fronthaul, featuring DWDM technology, supporting bidirectional transmission over a single fiber, with a maximum transmission distance of 20 kilometers.

I. Technical Decoding: Core Parameters and Design Principles

Form Factor & Data Rate: SFP28 form factor, operating at 25.78 Gbps, perfectly matching the 25G Ethernet and 5G fronthaul eCPRI interface standards.

Wavelength: 1330nm/1270nm (TX/RX), utilizing Bi-Directional (BiDi) technology over a single fiber to enable two-way communication.

Transmission Distance: Up to 20km, covering typical metro access and aggregation scenarios.

Key Optical Performance: Transmit power 0~6dBm, receiver sensitivity <-14dBm, providing a 14dB power budget to accommodate fiber loss.

Laser & Diagnostics: Employs a DFB laser to ensure signal quality and supports Digital Diagnostic Monitoring (DOM) for manageability and control.

Its design follows the core principle of Dense Wavelength Division Multiplexing (DWDM): multiplexing optical signals of different wavelengths onto a single fiber for transmission, multiplying capacity. The single-fiber BiDi technology is the masterstroke. By using paired, complementary wavelengths at each end of the fiber (e.g., End A transmits at 1330nm/receives at 1270nm, while End B transmits at 1270nm/receives at 1330nm), it achieves full-duplex communication using just one fiber strand. This directly doubles fiber resource utilization, greatly alleviating pressure on scarce urban duct resources.

II. Core Advantages of the 25G SFP28 DWDM 20km Transceiver

Exceptional Fiber Resource Efficiency: In urban areas where fiber duct deployment is costly and resources are limited, the combination of DWDM and BiDi technologies enables a single fiber to carry dozens of 25G channels. Compared to traditional dual-fiber solutions, this saves up to 50% or more in fiber resources, making it key for rapid and economical network expansion.

Future-Proof Smooth Evolution: This solution provides a standardized metro-area approach for applications like 5G fronthaul. Its architecture is typically passive, requiring no amplifiers, highly reliable, and its capacity can be scaled linearly by adding wavelengths, protecting operator investment.

Powerful Service Carrying and O&M Capabilities: The transceiver is protocol-transparent, seamlessly carrying various services like Ethernet, OTN, and CPRI/eCPRI. The built-in DOM function allows O&M personnel to monitor key parameters such as optical power, temperature, and voltage in real-time, enabling precise fault , thereby enhancing network availability.

III. Practical Application: Key Considerations for Deployment

Understanding parameters alone is insufficient for actual network deployment; engineering details are crucial for success.

Accurate Link Budget: The prerequisite for stable system operation is that the total link loss < transceiver power budget. Total loss includes fiber attenuation (~8dB for 20km @ 0.4dB/km), connector insertion loss (~0.5dB per connector), and WDM multiplexer/demultiplexer insertion loss. Precise calculation with sufficient margin is essential during design.

Strict Pairing Management: Single-fiber BiDi transceivers must be used in matched pairs with strictly corresponding wavelengths. A clear labeling management system must be established during procurement, storage, and deployment to prevent link failure due to misuse.

Environmental Adaptation Challenges: Laser wavelength drifts with temperature (~0.08nm/°C). For outdoor industrial temperature ranges (-40°C to +85°C), it is necessary to select industrial-grade transceivers with temperature control or ensure the wavelength drift remains within the DWDM channel tolerance. Otherwise, signal degradation will occur.