25G CWDM 20km Optical Module Empowers 5G Fronthaul and Data Center Interconnection

With the continuous large-scale deployment of 5G networks and the explosive growth of AI computing power demand, the high-speed optical module market is facing unprecedented opportunities. Against the backdrop of increasingly strained transmission links and fiber optic resources on the base station side, Coarse Wavelength Division Multiplexing (CWDM) technology, with its significant wavelength multiplexing capability, is becoming the mainstream choice for 25G Ethernet and 5G fronthaul networks.

I. Product Overview: Ideal Solution for High-Speed, Long-Distance Transmission

The C-LIGHT 25G CWDM SFP28 20km optical transceiver module is a high-performance, industrial-grade transmission solution. It adopts a standard SFP28 hot-pluggable form factor and is designed for applications such as 25G Ethernet, 5G fronthaul (CPRI/eCPRI), and data center interconnection. Using a pair of single-mode fibers, this module achieves a maximum transmission rate of 25.78Gbps over distances up to 20km, making it an ideal choice for metro aggregation and medium-distance DCI interconnection.

The C-LIGHT CWDM product line covers multiple wavelength channel combinations. The first six wavelengths (1270nm–1370nm) employ a cost-effective configuration using uncooled DML lasers and PIN detectors, supported by a mature industrial chain to meet the needs of six-wavelength base stations. The latter six wavelengths (1470nm–1610nm) use EML laser solutions to meet the requirements of longer transmission distances and stricter dispersion compensation. This flexible product matrix allows C-LIGHT to provide differentiated options for various link budgets and application needs.

II. Technical Highlights: Core Advantages of the CWDM Solution

The core advantage of CWDM technology lies in its wide channel spacing of 20nm. Compared with DWDM solutions, CWDM lasers do not require expensive active temperature control devices (TECs), significantly reducing the overall power consumption and cost of the optical module while simplifying system design. The C-LIGHT 25G CWDM 20km module embodies the strengths of this technical approach.

Key technical specifications demonstrate excellent performance:

- Low Power Design: Maximum power consumption is controlled within 1.5W, with typical power consumption around 1.2W, powered by a single +3.3V supply, effectively reducing the energy load and cooling requirements of network equipment.

- Wide Operating Temperature Range: Supports commercial grade (0°C to +70°C) and industrial grade (-40°C to +85°C) operating temperatures, adapting to various complex environments from indoor data centers to outdoor base stations.

- Full Protocol Compatibility: Compliant with mainstream industry standards such as SFP28 MSA, SFF-8402, SFF-8432, and IEEE 802.3cc, ensuring good interoperability with switches and transmission equipment from different brands.

- Digital Diagnostic Monitoring (DDM/DOM): Built-in digital diagnostic monitoring function allows real-time reading of key parameters such as module temperature, voltage, bias current, transmitted and received optical power via the host device’s I2C interface, greatly improving network management convenience and fault diagnosis efficiency.

- Superior Optical Link Budget: Select models offer up to 15dB power budget and are equipped with APD high-sensitivity receivers, ensuring low bit error rates and high signal integrity over 20km long-distance transmission.

Additionally, the C-LIGHT 25G CWDM module features a hot-pluggable design, supporting installation and replacement without shutting down system power, greatly simplifying network equipment maintenance and upgrades.

III. Application Scenarios: Multi-Dimensional Fulfillment of Network Requirements

1. 5G Fronthaul Networks

The rapid deployment of 5G networks imposes stringent requirements on fronthaul links, including high speed, low latency, and high capacity. 25G CWDM optical modules, with their mature industrial chain and cost advantages, have become one of the most widely adopted solutions in 5G fronthaul. In 5G fronthaul scenarios, operators deploy CWDM multiplexers and optical modules between the DU (Distributed Unit) and AAU/RRU (Active Antenna Unit/Remote Radio Unit), using a single fiber to carry six or twelve 25G services, effectively conserving valuable fiber optic resources.

2. Data Center Interconnection

With the widespread adoption of leaf-spine architectures in data centers, demand for uplink connections at 25G and even 100G rates continues to rise. The C-LIGHT 25G CWDM optical module provides a highly cost-effective solution for intra-data-center and inter-data-center connectivity. By multiplexing fiber resources within the metro area, this module significantly reduces data center construction costs and operational expenses.

3. Metro Aggregation Networks

In metropolitan Ethernet and access network aggregation layers, the C-LIGHT 25G CWDM optical module can be flexibly deployed between aggregation switches, efficiently aggregating and forwarding traffic within 20km distances, providing high-performance, high-reliability transmission connections for telecom operators and enterprise customers.

4. Enterprise and Campus Backbones

For large enterprise campus networks spanning multiple buildings or campuses, the C-LIGHT 25G CWDM optical module can be used in conjunction with CWDM multiplexers/de-multiplexers to carry multiple 25G Ethernet services over a single fiber, greatly improving fiber utilization and ensuring sufficient bandwidth for scenarios such as video conferencing and big data transmission.

IV. C-LIGHT: Technical Expertise from a Professional Optical Module Manufacturer

Founded in 2011, C-LIGHT has over 15 years of industry experience. Its product portfolio covers full-series high-speed optical modules including 800G, 400G, 200G, 100G, 50G, and 25G, as well as AOC/DAC active optical cables and CWDM/DWDM passive components. The company has over 50 professional R&D engineers and a daily production capacity exceeding 8,000 optical modules, with products exported to more than 100 countries and regions, establishing a strong brand reputation and customer trust in the industry.

C-LIGHT places special emphasis on customized service capabilities, offering one-stop solutions from chip selection, circuit design, and firmware development to customized host software, meeting diverse customer needs for consistent quality, fast delivery, and private customization.

V. Market Outlook and Future Prospects

According to industry forecasts, the global coarse wavelength division multiplexing module market was valued at approximately $3.04 billion in 2025 and is expected to grow at a compound annual growth rate of about 8.07%. With the deepening of 5G coverage, the advancement of 6G pre-research, and the continued surge in demand for high-speed optical interconnection driven by AI computing networks, 25G CWDM products will maintain strong vitality in the medium-to-long-distance transmission field.

C-LIGHT will continue to leverage its strong R&D capabilities and mature supply chain, constantly optimizing product performance and expanding its product portfolio to deliver higher-quality, more cost-effective optical module products and solutions to customers worldwide.