Dispersion penalties for 10 Gbit/s optical transmission using external modulators and low chirp lasers

摘要

The use of external modulators without chirp (pure IM) in conjunction with a CW-laser diode leads to a two-sided optical spectrum that is limited in width by the information-bandwidth. So far chirp of directly modulated lasers has been considered as source of additional spectral broadening. Therefore external modulation has been used predominately for high bit-rate optical data transmisssion. However mixed FM and IM, procuded by a low chirp laser, can lead to the partial suppression of one of the sidebands and, as shown in this paper, to a reduced dispersion penalty.