A junior engineer is implementing one of your optical designs and asks about CWDM (Coarse Wavelength Division Multiplexing). Which two features describe CWDM? (Choose two.)

CWDM is designed for shorter distances (typically up to 80 km) and cannot use erbium-doped fiber amplifiers (EDFAs) for optical amplification because its wide channel spacing extends outside the EDFA gain band.

CWDM supports up to 18 wavelength channels (1270-1610 nm at 20 nm spacing), not 32; it is DWDM that supports 32 or more channels using much tighter 0.8 nm or narrower spacing.

CWDM uses wavelengths from 1270 nm to 1610 nm with 20 nm channel spacing, a range that overlaps with DWDM's C-band (1530-1565 nm) and L-band (1565-1625 nm). Because of this shared spectral region, both technologies operate within the same low-loss transmission window of standard single-mode fiber.

The 850 nm band is used for short-reach multimode fiber applications such as 10GBase-SR; CWDM operates in the 1270-1610 nm range on single-mode fiber.

CWDM mux/demux devices use passive thin-film filters or prisms to split and combine wavelengths without any active electronics. Because no powered components are required, these passive CWDM devices operate without electrical power, simplifying installation and reducing operating costs.