Which two descriptions of CWDM are true? (Choose two)

Question

Options

• Atypically used over long distances, but requires optical amplification
• Buses the 850nm band
• Callows up to 32 optical earners to be multiplexed onto a single fiber
• Dshares the same transmission window as DWDM
• EPassive CWDM devices require no electrical power

• A
  3% (1)
• B
  3% (1)
• C
  6% (2)
• D
  89% (32)

Explanation

CWDM (Coarse Wavelength Division Multiplexing) uses 20nm channel spacing across wavelengths from 1270nm to 1610nm. Option D is correct: CWDM and DWDM share overlapping transmission windows - DWDM operates in the C-band and L-band, both of which fall within the CWDM wavelength range. Option E is correct: passive CWDM multiplexers/demultiplexers use thin-film filters or fiber Bragg gratings that operate purely on optical principles and require no electrical power. The other options are false: CWDM is designed for short-to-medium distances (≤80km) and cannot use EDFA amplification because its wide channel spacing spans wavelength regions outside the erbium amplifier gain band (eliminating A); CWDM does not use the 850nm band, which is reserved for short-range multimode fiber (eliminating B); CWDM supports up to 18 channels, not 32 - DWDM can achieve 80+ channels (eliminating C).

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