Isolator-free transmission at 2.5 Gbits/s over 100 km of single-mode fiber by a 1.55-/spl mu/m, AlGaInAs strained-multi-quantum-well, directly modulated distributed-feedback laser diode

The performance of 1550 nm, distributed feedback laser diode modules without an optical isolator is presented. The laser has a complex coupled grating formed by current injection with a strong coupling coefficient of /spl kappa/ = 45 + 30i cm/sup -1/. The spectrum, relative intensity noise, and bit-error rate were characterized with up to 20% back reflection into the module. Through error rates of 10/sup -10/, no error floor was found and the dispersion penalty remained less than 2.0 dB for a data rate of 2.5 Gbits/s over 100 km of SMF-28.