Tm-doped fiber amplifiers for 1470-nm-band WDM signals

We describe the gain characteristics of thulium-doped fiber amplifiers (TDFA) for wavelength division multiplexing (WDM) signals. We optimized the TDF length and the ratio between the forward and backward pump power to realize efficient amplification. The TDFA achieved a gain of over 20 dB and a noise figure of less than 6 dB in the 1353-1483 nm wavelength region at a total pump power of 300 mW for WDM signals input at a total power of -7 dBm.