What type of light source is typically used in multi-mode fiber optics?

In multi-mode fiber optics, light-emitting diodes (LEDs) are commonly used as the light source. This is due to their ability to emit light over a range of wavelengths, which can be effectively launched into the core of multi-mode fiber. LEDs produce a broad spectrum of light, making them well-suited for multi-mode applications where multiple light modes can propagate through the fiber simultaneously.

The nature of multi-mode fiber, which has a larger core diameter than single-mode fiber, allows for the utilization of LEDs, which provide a cost-effective and practical lighting solution. LEDs are also advantageous in terms of lower power consumption and simpler circuitry compared to laser sources.

By contrast, laser diodes, while they can be used in multi-mode systems, are primarily associated with single-mode fiber optics due to their focused and coherent light output, which is ideal for long-distance transmission. Incandescent bulbs and halogen lamps are not typically used in fiber optics applications due to their inefficiency and the nature of their light output, which does not match the requirements for coupling effectively into fiber optics.