First demonstration of dispersion limit improvement at 20 Gb/s with a dual electro-absorption modulated laser

The dual electro-absorption modulated laser (D-EML) is a transmitter technology based on integrated electro-absorption modulated laser (EML) with dual independent-access modulation. The D-EML allows the adjustment of the laser and modulator chirp by controlling the amplitude modulation in order to enhance the transmission distance without increasing consumption, cost and complexity. We successfully demonstrate experimentally and by simulation an error-free 39.7-km transmission at 20 Gb/s in standard dispersion fiber without any compensation fiber using D-EML. 1. Introduction Today, new high-speed, low cost and low consumption optical sources are becoming a necessity for the deployment of extended-reach access and metropolitan networks. Binder and Kohn [1] have defined some conditions between the frequency (FM) and amplitude (AM) modulation that lead to a reduction of the spectral content of the side band for OOK signals. Indeed, this condition allows spectrum sculpting for dealing with fiber dispersion. It acts on the adiabatic chirp matching the optical frequency difference between marks and space symbols to fpp = m(B/2) where m is the intensity modulation depth and B is the signal bit rate. For a large extinction ratio this comes to inducing a -phase shift between two marks separated by a space and vice versa. This leads to a separation of space symbols producing an open eye and a low bit error rate (BER). However, Binder and Kohn conditions do not consider transient chirp known as detrimental in laser and electro-absorption modulator (EAM).