Which light sources are used to transmit data over fiber-optic cables?

Which light sources are used to transmit data over fiber-optic cables?

• A. LED
• B. Radio frequency
• C. Both Laser and LED
• D. Laser

Answer: (C)

Fiber-optic transmission carries data by modulating light, so the light source you choose directly affects distance, speed, and cost. Two common light sources are laser diodes and LEDs. Laser diodes produce a tight, coherent beam with a narrow spectral width, which makes them ideal for long-distance, high-bandwidth links because the signal stays well-behaved as it travels through the fiber. LEDs, by contrast, emit incoherent light with a broader spectrum and are typically cheaper and easier to drive, which suits short-reach networks where extremely high speeds aren’t needed. Since both can be used to encode data onto light for transmission, both are valid choices depending on the application. Radio frequency isn’t a light source for fiber-optic transmission; it’s a different medium of carrying signals and isn’t used to light the fiber itself.

Fiber-optic transmission carries data by modulating light, so the light source you choose directly affects distance, speed, and cost. Two common light sources are laser diodes and LEDs. Laser diodes produce a tight, coherent beam with a narrow spectral width, which makes them ideal for long-distance, high-bandwidth links because the signal stays well-behaved as it travels through the fiber. LEDs, by contrast, emit incoherent light with a broader spectrum and are typically cheaper and easier to drive, which suits short-reach networks where extremely high speeds aren’t needed. Since both can be used to encode data onto light for transmission, both are valid choices depending on the application. Radio frequency isn’t a light source for fiber-optic transmission; it’s a different medium of carrying signals and isn’t used to light the fiber itself.