For testing FTTx installations, optical power meters should be calibrated for which wavelengths?

The correct answer identifies the wavelengths most commonly associated with FTTx (Fiber to the x) installations, which typically use optical fibers for data transmission. The wavelengths of 1,490 nm, 1,550 nm, and 1,577 nm are specifically significant for the operation of passive optical networks (PONs) that are widely deployed in FTTx architectures.

1,490 nm is often used for downstream transmission, while 1,550 nm is a standard wavelength for long-distance optical communication due to its low attenuation in optical fiber. The wavelength 1,577 nm is also critical as it is used for upstream signals in some PON applications, making it essential for ensuring accurate testing and performance verification in these systems.

The other options include wavelengths that are either not commonly used in current FTTx standards or are not optimal for effective testing of the setups involved in this type of installation. For example, while the 1,310 nm and 1,550 nm wavelengths are important for different applications, the inclusion of 980 nm without the standard context for FTTx may not represent the full certainty in terms of testing parameters for optical power meters used in these networks.