How to read the markings on an optical module

Optical module markings indicate key parameters, manufacturer information, and operational specifications, helping users identify module type, performance, and compatibility.

Key Markings and Their Meanings

1. Module Type and Form Factor Optical modules are labeled with their form factor, such as SFP, SFP+, SFP28, QSFP+, QSFP28, XFP, or CFP. This indicates the physical size, connector type, and supported data rate. For example, XFP modules support 10 Gbit/s, while SFP28 supports 25 Gbit/s, and QSFP28 can support 100 Gbit/s . 2. Manufacturer and Part Number The label typically includes the manufacturer name, logo, and part number, which helps identify the module for ordering, warranty, and compatibility purposes . 3. Optical Power Ratings

• Average Optical Power (Tx Power): Indicates the light intensity emitted by the transmitter under normal conditions, measured in mW, W, or dBm. It reflects the module's ability to transmit signals over a given distance .
• Receiver Sensitivity (Rx Power): Shows the minimum optical power required for the receiver to correctly interpret signals. 4. Extinction Ratio The extinction ratio is the ratio of optical power when transmitting a logical “1” to the power when transmitting a “0,” measured in dB. It indicates the laser's ability to distinguish between high and low signals, affecting signal quality . 5. Wavelength Modules are marked with their operating wavelength, such as 850 nm, 1310 nm, or 1550 nm, which must match the fiber type and network design . 6. Digital Diagnostic Monitoring (DDM/eSFP) Some modules, especially eSFP, include markings indicating support for voltage, temperature, bias current, transmit and receive optical power monitoring. This allows real-time diagnostics via the I²C interface . 7. Connector and Orientation Indicators Labels may include connector type (LC, MPO) and orientation marks, such as an L-shaped notch on QSFP+ modules, to ensure correct insertion . 8. Compliance and Standards Modules often display standards compliance, such as SFF-8472, RoHS, or CE, indicating adherence to industry specifications and environmental regulations .

Practical Tips for Reading Markings

• Always check the data rate and wavelength to ensure compatibility with your network.
• Observe orientation marks to avoid incorrect insertion, which can damage the module or port.
• Use DDM readings to monitor module health and prevent network issues.
• Compare Tx and Rx power ratings with link budget calculations to ensure reliable transmission. Understanding these markings ensures proper selection, installation, and maintenance of optical modules, optimizing network performance and reliability .