Which sources of light are commonly used in fiber optic transmission?

Laser diodes and LEDs are the primary sources of light used in fiber optic transmission due to their ability to emit light in narrow wavelengths and their efficiency in coupling light into fiber optic cables.

Laser diodes are particularly advantageous because they produce coherent light, which means the light waves they emit maintain a constant phase relationship and can be focused into a tight beam. This property allows for minimal loss of signal strength over long distances, which is vital for effective data transmission in fiber optics.

LEDs (Light Emitting Diodes), while less focused than laser diodes, also play a significant role, especially in short-range applications. They are robust, have a longer operational lifespan, and are generally less expensive, making them suitable for many fiber optic systems that do not require extremely high data rates or long transmission distances.

The other options typically do not provide the necessary characteristics for efficient fiber optic transmission. Thermal emitters and incandescent bulbs produce broad-spectrum light, which is unsuitable for the precision needed in fiber optics, while fluorescent tubes and halogen lights vary widely in output and do not offer the necessary coherence. Standard light bulbs and gas discharge lamps also lack the specific properties required for efficient coupling into fiber optics, making them less practical for this application.