In what spectrum of light do the fiber optic wavelengths take place?

In what spectrum of light do the fiber optic wavelengths take place?

• A. Infrared
• B. Visible
• C. Ultraviolet
• D. Microwave

Answer: (A)

Infrared light is used because glass fibers have their lowest signal loss in that region, especially at the telecom wavelengths around 1300–1550 nm. This near-infrared range combines efficient transmission through silica with practical light sources and detectors (like laser diodes and LEDs) that operate well there, and it minimizes dispersion for long-distance communication. The fiber remains highly transparent in this band, so the light can stay confined by total internal reflection in the core. Visible light would experience higher attenuation and scattering in silica, making long-distance links inefficient. Ultraviolet light is strongly absorbed and can damage the fiber, while microwaves are too long to be confined effectively by a conventional optical fiber.

Infrared light is used because glass fibers have their lowest signal loss in that region, especially at the telecom wavelengths around 1300–1550 nm. This near-infrared range combines efficient transmission through silica with practical light sources and detectors (like laser diodes and LEDs) that operate well there, and it minimizes dispersion for long-distance communication. The fiber remains highly transparent in this band, so the light can stay confined by total internal reflection in the core.

Visible light would experience higher attenuation and scattering in silica, making long-distance links inefficient. Ultraviolet light is strongly absorbed and can damage the fiber, while microwaves are too long to be confined effectively by a conventional optical fiber.