抄録
The growing need for increases in the transmission capacity of optical communications has driven research efforts of broadband fiber amplifiers that can fully exploit the low-loss region of silica fibers (1450-1650 nm, <0.25dB/km). The so-called S-band (1480-1530nm) is becoming more promising as a candidate for the next-generation transmission band. By using 1.05- and 1.56-?Em dual-wavelength pumping, we first demonstrated a gain-shifted thulium-doped fiber amplifier (GS-TDFA) operating at the S-band. We have then demonstrated a highly-efficient (29%) and high-power (+21.5dBm) GS-TDFA by use of practical laser-diode pumping of 1.4 and 1.56?Em. With the GS-TDFA, a record 10.92-Tb/s capacity WDM transmission has recently been demonstrated. In this paper, we review these recent results by starting from thebasic operational concept of gain shifting. Amplification and transmission characteristics confirm the applicability of GS-TDFAs to large-capacity field-use WDM networks.
