Complex sentence: To create Raman gain, pump lasers are coupled into the fiber by wavelength-division multiplexers, with wavelengths of pump lasers chosen to create a broadband and flat gain profile that covers the spectrum of the broadband optical pulse.
Split into simpler sentences: To create Raman gain, pump lasers are coupled into the fiber by wavelength-division multiplexers. The wavelength of pump lasers is chose to create a broadband and flat gain profile that covers the spectrum of the broadband optical pulse.