A theoretical and experimental investigation of catastrophic amplification
of broadband noise in optical fibers near the zero-dispersion frequency (v(
0)) pumped by two lasers with frequencies that are symmetrically tuned rela
tive to v(0) is presented. The effect is due to a four-wave mixing (FWM) pr
ocess, phase matched up to third-order dispersion, between the spectral com
ponents of noise and the lasers. We observed a FWM gain of 16 dB (10-dB net
gain) over a 22-nm bandwidth (limited by fourth-order dispersion) for 18-d
Bm power lasers at +/-1 THz (8 nm) from v(0) in a 25-km-long dispersion-shi
fted fiber. A simple analytical model is proposed that will permit us to in
vestigate this effect numerically in amplified links with concatenated ampl
ifiers and consider random fluctuations of v(0) along the fiber. (C) 2001 O
ptical Society of America.