What wavelength is used for optical cable testing

The standard test wavelengths for optical cables are 850 nm and 1300 nm for multimode fibers, and 1310 nm and 1550 nm for singlemode fibers.

Standard Wavelengths by Fiber Type

• Multimode Fiber (MMF): Typically tested at 850 nm and 1300 nm. These wavelengths correspond to the operating wavelengths of LEDs or VCSELs used in multimode networks and are chosen because multimode fibers are optimized for these ranges, balancing attenuation and modal dispersion .
• Singlemode Fiber (SMF): Typically tested at 1310 nm and 1550 nm. These wavelengths are selected because singlemode fibers have minimal attenuation and dispersion at these points, ensuring accurate measurement of insertion loss and overall fiber performance .

Testing Considerations

• Power Meter Calibration: Optical power meters and light sources are calibrated at these standard wavelengths to ensure accurate loss measurements .
• Network Operation: Testing should be performed at the same wavelength(s) that the network will operate on, as recommended by Corning and other industry standards .
• Plastic Optical Fiber (POF): For POF, shorter wavelengths like 650 nm are commonly used due to lower absorption in plastic materials .

Advanced Systems

• Wavelength-Division Multiplexing (WDM): In systems using DWDM or CWDM, testing may involve additional precise wavelengths within the 1260–1670 nm range to match the operational channels .

Standards and Guidelines

• IEC 60793-1-44: Provides guidance for measuring cut-off wavelengths and other fiber properties, ensuring consistent testing for singlemode fibers .
• TIA-568.3-D and FOA Guidelines: Recommend using optical loss test sets (OLTS) or light source and power meter (LSPM) at the network's operating wavelengths for Tier 1 testing, with bidirectional testing preferred for accuracy . In summary, 850 nm and 1300 nm for multimode fibers, and 1310 nm and 1550 nm for singlemode fibers are the standard test wavelengths, chosen to match fiber characteristics and ensure reliable measurement of insertion loss and overall network performance. Testing at these wavelengths is essential for compliance with industry standards and accurate verification of fiber optic installations.