Question

Optical communication using fibres is performed in the frequency range of:

• A. 1 GHz - 1000 GHz
• B. 1 THz - 1000 THz
• C. 1 kHz - 1000 kHz
• D. 1 MHz - 1000 MHz

Hint:

Fibre optics = visible/near-infrared light.
Use $f = c / \lambda$ to estimate frequency.
THz range corresponds to wavelengths of 300 nm – 1 mm.
Important: radio/microwave frequencies are too low for optical fibres.

Answer 1

The Correct Option is B

• Optical fibres use light as the carrier signal.
• Frequency of visible light: $f = c / \lambda$, $\lambda \sim 400 - 1500$ nm.
• Compute $f$: $c = 3 \times 10^8$ m/s, $\lambda = 1.5 \times 10^{-6}$ m → $f \sim 2 \times 10^{14}$ Hz.
• Hence optical communication range = 1 THz – 1000 THz.