CWDM uses lasers too, the reduced wavelength tolerance simply means that the lasers can be uncooled (reducing the power draw) and that chirp (frequency shift du

CWDM uses lasers too, the reduced wavelength tolerance simply means that the lasers can be uncooled (reducing the power draw) and that chirp (frequency shift during modulation) does not cause interference with neighbouring channels, making them easier to modulate directly. The 'loose' CWDM banding is actually smaller than the bandwidth of typical LEDs.