A mode of light is best defined as a _____.

A mode of light is best defined as a light-ray path. In the context of fiber optics, a mode refers to the specific pattern in which light travels through the fiber. Each mode represents a distinct way that light can propagate in the optical fiber, based on the fiber's refractive index profile and core structure.

In multimode fibers, for instance, multiple modes can propagate simultaneously, allowing different pathways for light to travel through the fiber. This is critical to understanding how fiber optics work, as it influences the performance parameters such as bandwidth and signal quality.

The other terms—light wavelength, light intensity, and light source—refer to different aspects of light that do not capture the concept of modes as effectively. Wavelength relates to the color or frequency of the light, intensity measures the power or brightness of the light, and a light source indicates where the light originates. However, none of these aspects directly correspond to the pathway that light takes within a fiber, making the definition centered on the light-ray path the most accurate one for defining a mode in fiber optics.