Suppression of Relaxation Oscillations in DFB Lasers through Shaping Injection Current Waveforms

The application of direct modulation, the simplest modulation mode for optical communication, is limited in a few specific fields due to delay time (DT) and relaxation oscillations (ROs). We present a method of shaping injection current waveforms for the direct modulation of distributed feedback (DFB) lasers. By means of the phase space technique, we find that the injection of shaped current into the circuit model of DFB lasers allows for the suppression of ROs without increasing DT. Hence, the optical information can be transmitted over much longer distances at a high data rate.