title: Gain-flattened fiber Raman amplifiers with nonlinearity-broadened pumps.
abstract: Gain flattening of an E-band (1360-1460-nm) fiber Raman amplifier was achieved by pump spectral broadening to a 16.3-nm linewidth by use of nonlinearity in a 6.2-km standard fiber. With the broadened pump, the characteristic Raman gain ripple was removed and the 3-dB gain bandwidth was increased by 10.6 nm relative to the nonbroadened pump case. The experimental results agreed well with a gain profile simulation. The use of a 100-m holey fiber for pump broadening was also investigated near 1.56 microm for U-band (1625-1675-nm) Raman amplifiers. Much less broadening was observed, which is believed to be a result of less four-wave mixing.
authors.affiliation: Femtosecond Optics Group, Department of Physics, Imperial College London, Prince Consort Road, London SW7 2BW, UK. david.chestnut@imperial.ac.uk
authors.forename: D A
authors.initials: DA
authors.lastname: Chestnut
authors.forename: J R
authors.initials: JR
authors.lastname: Taylor