Single-frequency MOPA Er/sup 3+/ DBR fiber laser for WDM digital telecommunication systems

The realization, the characteristics and the bit-error-rate (BER) performance of a single frequency, linear polarization Er/sup 3+/-doped distributed Bragg reflector fiber laser are reported. The device, pumped at 980 nm, gives a maximum output power of 13 mW with an overall slope efficiency /spl eta/=24%, a continuous-wave intensity ripple around 1% and a linewidth of 2.2 kHz. The BER test, performed without any polarization control system in a complete 475-km-long 2.5-Gb/s wavelength-division-multiplexed transmission line, shows only a 0.5-dB penalty is introduced.