Insertion Loss Tested with Optical Power Meter

An optical power meter test measures the insertion loss of a fiber optic link by comparing the light output at the far end to a calibrated reference, using a light source and power meter setup.

Equipment Required

To perform an insertion loss test, you need:

• Optical Power Meter (OPM): Measures the optical power received at the far end of the fiber link .
• Optical Light Source (OLS): Provides a stable light signal at the required test wavelength(s) (commonly 850 nm, 1300 nm for multimode, and 1310 nm, 1550 nm for single-mode), .
• Reference Cables: Short, low-loss fibers used to set the 0 dB reference .
• Connectors/Adapters: Compatible with the fiber under test to ensure accurate coupling.

Test Procedure

1. Set the Reference: Connect the light source to a reference cable and the power meter to a receive reference cable. Measure the power to establish the 0 dB reference. Depending on connector compatibility, you may use a one-, two-, or three-cable reference method .
2. Connect the Fiber Under Test: Replace the reference cable with the fiber link to be tested, keeping the light source and power meter connections intact.
3. Measure Power: Record the optical power at the far end using the power meter.
4. Calculate Insertion Loss: Subtract the measured power from the reference power to determine the insertion loss in dB. This includes connector losses, splice losses, and fiber attenuation .

Best Practices

• Ensure clean and properly seated connectors to avoid measurement errors.
• Use short reference cables (typically <2 m) to minimize their contribution to loss .
• Test at multiple wavelengths if required by standards or network specifications .
• For high-density or MPO networks, specialized testers like the VIAVI SmartClass™ MPOLx can automate insertion loss measurements across multiple fibers .
• Combine with OTDR testing for detailed characterization of individual splices and connectors, especially in long or complex links .

Standards and Certification

• Tier 1 Testing: OLTS (Optical Loss Test Set) measurements using a light source and power meter to verify total link loss .
• Tier 2 Testing: Combines OLTS and OTDR for detailed link analysis, including individual events .
• Follow TIA and ISO standards for fiber testing to ensure compliance and reliable results . By following these steps and using proper equipment, an optical power meter test provides an accurate measurement of insertion loss, ensuring the fiber link meets performance requirements.