What two wavelengths do single-mode fibers most commonly use?

What two wavelengths do single-mode fibers most commonly use?

• A. 1310, 1550
• B. 850, 1300
• C. 1550, 1625
• D. 1310, 1000

Answer: (A)

Wavelengths around 1.3 and 1.55 micrometers are preferred for single‑mode fiber because silica fiber performs best there. At about 1310 nm the dispersion is near zero, so pulses travel with minimal spreading and intersymbol interference is reduced—making this window ideal for many data links. Around 1550 nm the loss is at its lowest in standard silica fiber, which allows signals to travel much longer distances between amplifiers. This window also aligns with efficient erbium-doped fiber amplifiers, enabling practical long‑haul transmission. Together, these two windows provide low dispersion and low loss, plus strong amplification options, which is why they’re the most commonly used pair.

Wavelengths around 1.3 and 1.55 micrometers are preferred for single‑mode fiber because silica fiber performs best there. At about 1310 nm the dispersion is near zero, so pulses travel with minimal spreading and intersymbol interference is reduced—making this window ideal for many data links. Around 1550 nm the loss is at its lowest in standard silica fiber, which allows signals to travel much longer distances between amplifiers. This window also aligns with efficient erbium-doped fiber amplifiers, enabling practical long‑haul transmission. Together, these two windows provide low dispersion and low loss, plus strong amplification options, which is why they’re the most commonly used pair.