What is the significance of the 'cut-off wavelength' in fiber optics?

The significance of the 'cut-off wavelength' in fiber optics lies in its role in determining the operational characteristics of optical fibers, especially in distinguishing between multi-mode and single-mode fibers. The cut-off wavelength is the specific wavelength at which a multi-mode fiber begins to support only a single mode of light propagation. When the operating wavelength is higher than this cut-off point, the fiber will exhibit single-mode behavior, allowing for lower signal loss and higher transmission distances.

This phenomenon is crucial for applications requiring high performance in long-distance communication, where single-mode fibers are preferred due to their reduced modal dispersion. Consequently, understanding the cut-off wavelength is essential for design and deployment considerations in fiber optic networks, ensuring optimal performance based on the desired application.

In contrast, the other options focus on different aspects that do not accurately represent the role of the cut-off wavelength in fiber optics, such as maximum fiber length, signal transmission minimums, or measurements of light intensity, which are not directly related to the definition and significance of the cut-off wavelength in fiber optics.