Optical FibreHardQuestion 20309
Question
An erbium-doped fibre amplifier (EDFA) is used in optical communication because it:
- AConverts optical signal to electrical, amplifies, then reconverts
- BAmplifies light directly in the 1550 nm window without O/E/O conversionCorrect
- CActs as a modulator at 1550 nm
- DProvides signal regeneration with retiming and reshaping
Correct answer
Amplifies light directly in the 1550 nm window without O/E/O conversion
Explanation
EDFA: Er³⁺ ions in the fibre are pumped (980 nm or 1480 nm laser) to an excited state. Signal photons at 1530–1565 nm trigger stimulated emission → direct optical gain (~20–40 dB). Can amplify entire WDM comb simultaneously → key enabler of terabit/s fibre networks. Gain bandwidth ~35 nm.