What is the consequence of using a mismatched wavelength setting on an optical power meter when measuring optical power?

The consequence of using a mismatched wavelength setting on an optical power meter when measuring optical power is an inaccurate power reading. Optical power meters are calibrated to measure power accurately at specific wavelengths. The detector within the power meter has a wavelength-dependent responsivity, meaning it responds differently to light of different wavelengths. The responsivity is a measure of how efficiently the detector converts optical power into an electrical signal. If the wavelength setting on the power meter does not match the wavelength of the optical signal being measured, the power meter will not accurately convert the optical power into an electrical signal, resulting in a measurement error. The magnitude of the error depends on the difference between the actual wavelength and the wavelength setting, as well as the characteristics of the power meter's detector. Some power meters have a relatively flat responsivity curve over a wide range of wavelengths, while others have a more peaked responsivity curve. In either case, using the correct wavelength setting is essential for accurate measurements. For example, if you are measuring the power of a 1550 nm signal but the power meter is set to 1310 nm, the power meter will likely underestimate the actual power level. This could lead to incorrect conclusions about the performance of the fiber optic link and could hinder troubleshooting efforts. Therefore, it is crucial to always verify that the wavelength setting on the optical power meter matches the wavelength of the optical signal being measured to ensure accurate and reliable power measurements.