Optical power meter measures light at a certain frequency

The light source for an optical power meter should operate at the same wavelength as the fiber optic system being tested, commonly 850 nm, 980 nm, 1270 nm, 1300 nm, 1310 nm, 1490 nm, 1550 nm, 1577 nm, 1625 nm, or 1650 nm.

Recommended Wavelengths

For accurate fiber optic testing, the optical power meter must match the wavelength of the light source. Standard wavelengths include: Multimode fibers: 850 nm and 1300 nmSingle-mode fibers: 1310 nm, 1490 nm, 1550 nm, 1577 nm, 1625 nm, 1650 nmSpecial applications: 980 nm and 1270 nm for certain telecom or PON systems Using the same wavelength ensures that the measured optical power accurately reflects the fiber's attenuation and insertion loss, as fiber loss varies with wavelength.

Practical Considerations

Calibration: Ensure the optical power meter is calibrated for the selected wavelength to maintain measurement accuracy. Dual or triple wavelength sources: Some light sources provide multiple wavelengths simultaneously, allowing testing of different fiber types without changing equipment. Single jumper method: For end-to-end loss testing, the light source sends light through the fiber, and the power meter reads the received power at the same wavelength.

Summary

Always set the optical power meter to the same wavelength as the light source used for testing. For multimode fibers, use 850 nm or 1300 nm; for single-mode fibers, use 1310 nm, 1490 nm, 1550 nm, or other telecom-specific wavelengths. Matching wavelengths ensures accurate measurement of optical power and fiber loss.