What does wavelength division multiplexing (WDM) do?

Wavelength Division Multiplexing (WDM) is a technology that allows multiple optical signals to be transmitted simultaneously over a single optical fiber. This is achieved by using different wavelengths (or colors) of light for each signal. By separating the data into different wavelengths, WDM effectively increases the capacity of a fiber optic cable, enabling it to carry more information without requiring additional physical fibers.

This method is crucial in telecommunications as it maximizes the use of existing fiber infrastructure, reducing costs and improving efficiency. Each wavelength can be modulated with its own data stream, enabling communication from various sources to be merged into one fiber cable, which can then be demultiplexed at the receiving end into individual signals, restoring them to their original state.

In contrast to the correct choice, other options describe unrelated functions. For example, reducing the distance light can travel contradicts the purpose of WDM, which aims to enhance transmission capabilities over long distances. Converting optical signals to electrical signals refers to a different process called optical-to-electrical conversion, which is not the primary function of WDM. Separating signals based on frequency is related to radio frequency techniques rather than optical wavelength division. Thus, the correct answer emphasizes the foundational principle of WDM in optical communications