Which type of light source is used in laser diodes for fiber optics?

Laser diodes used in fiber optics utilize coherent light as their light source. Coherent light is characterized by its waves being in phase and having a constant phase difference, which means that the light produced is highly focused and can travel long distances without significant divergence. This property is crucial for fiber optics, as coherent light can be efficiently transmitted through the optical fibers, maintaining signal integrity over long ranges.

In contrast, incandescent lights and fluorescent lights produce incoherent light, which lacks the phase consistency necessary for optimal transmission through fiber. Incoherent light sources emit a wide range of wavelengths and are not structured in such a way that they can maintain a uniform direction. This makes them ineffective for applications where precision and long-distance transmission are required, such as in fiber optic communication. Fluorescent lights also fall into the category of incoherent sources and would similarly not be suitable for fiber optic use. Thus, coherent light is the preferred choice for laser diodes in fiber optics applications.