Amplification of broadband noise pumped by two lasers in optical fibers

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.