What type of light source is commonly used for multi-mode fiber testing?

The use of a Light Emitting Diode (LED) as a light source for multi-mode fiber testing is prevalent due to its ability to effectively emit a broad spectrum of light and fill the core of multi-mode fibers. Multi-mode fibers have a larger core diameter compared to single-mode fibers, allowing multiple light modes to propagate simultaneously. LEDs are well-suited for this application because they can generate a wide range of wavelengths, typically in the near-infrared region, which aligns with the optimal transmission characteristics of multi-mode fiber.

Additionally, LEDs provide advantages such as lower cost, ease of use, and less stringent requirements for coupling light into the fiber, making them ideal for testing and troubleshooting multi-mode fiber optic cables. Their emission characteristics allow for effective testing over the various modes present in multi-mode transmission, thereby ensuring accurate performance measurements.

While other light sources like Helium-Neon lasers, Halogen lamps, or Laser Diodes can be used in specific scenarios (like single-mode testing or specialized applications), they do not match the practicality and suitability of LEDs for routine multi-mode fiber testing.