High-gain bidirectional Er3+-doped fiber amplifier for conventional- and long-wavelength bands

High average gains of greater than 31 dB have been obtained between 1530-15 60 nm (conventional-wavelength band, C-band) and 1570-1600 nm (long-wavelen gth band, L-band) using a saturating tone technique that represents 64 chan nels of a wavelength division multiplexed system. A bidirectional amplifyin g stage is utilized as high-power C-band and low-noise L-band stages. Noise figures of less than 3.6 and 5.4 dB are measured for the C- and L-bands, r espectively.