Effects of signal seeding on long-wavelength-band Er3+-doped fiber amplifiers

A study of gain improvement in the long-wavelength band (L-band) by a seedi ng signal from the conventional-wavelength band (C-band) is presented. The seeding signal reduces losses through amplified spontaneous emission and su pplies energy for L-band amplification in the underpumped region. Gain impr ovement is observed for a copumped configuration, where the L-band and seed ing signal are colaunched together with minimal noise figure penalty when a n optimized seeding signal is used. The seeding signal boosts the L-band ga in profile in the underpumped region to the flat-gain profile with gain fla tness of less than 1 dB. High flat-gain values of 24 dB with gain variation of less than 0.9 dB when a seeding signal at 1555 nm is applied to the L-b and amplifier pumped by only 105 mW from a 980 nm pump laser, A gain improv ement of 52 dB is obtained at 1580 nm with this architecture. (C) 2001 Soci ety of Photo-Optical Instrumentation Engineers.