Improved direct modulation technique for faster switching of diode lasers

The direct modulation of diode laser output for optical data transmission is the oldest encoding technique and the simplest but is plagued by problems (delay time and relaxation oscillations) which limit its usefulness to a small number of niche applications. Using a phase space representation of the transient, it is shown that a simple modification of the shape of the injected current's switch may dramatically improve the performance of this old technique, both for the switch-up as well as for the switch-down of the laser. Below- and above-threshold biasing schemes are considered and a physical discussion of the realisability of the technique is offered.