In which type of fiber does light travel straight through the core at a single angle?

Light travels straight through the core at a single angle in single-mode fiber. This type of fiber has a small core diameter, typically around 8 to 10 microns, which allows only one mode of light to propagate. Because of this single mode of propagation, light travels in a straight line, reducing modal dispersion, which can negatively impact signal quality over long distances.

In contrast, multimode fiber has a larger core diameter, usually around 50 to 62.5 microns, allowing multiple modes of light to travel simultaneously. This results in light traveling at various angles, which can lead to modal dispersion and affect signal clarity over longer distances. Coaxial and hybrid cables do not fall under the category of fiber optics; coaxial cable is typically used for electrical signals, and hybrid cables combine different technologies rather than focusing on light transmission through a fiber core.