Transmission of M-QAM signals using an unisolated DFB laser

We examine the transmission of M-ary quadrature-amplitude modulated (M-QAM) signals using an unisolated distributed-feedback (DFB) laser. Since forward-error-correction is readily available, it is employed in the experiments. We demonstrate that unisolated DFB's can transmit over 80 64-QAM channels; these could carry 500 compressed video channels.