1480-1510 nm-band Tm doped fiber amplifier (TDFA) with a high power conversion efficiency of 42 %

The highest reported power conversion efficiency of 42 % has been achieved using a high Tm/sup 3+/ concentration doped fluoride fiber amplifier with one color 1.4 /spl mu/m pumping and a double pass configuration for S-band amplification. We achieved gains exceeding 26 dB and NFs of less than 7 dB in the 1480 to 1510 nm wavelength region (30 nm bandwidth). Furthermore, an 8 /spl times/ 10 Gb/s transmission experiment clarified that there was no excess noise generated in our proposed gain-shifted GS-TDFAs.