Epitaxial and cavity design optimisation for the next generation of InP semiconductor laser devices

In the first part of the study, the epitaxial structure was studied, in particular, the doping concentration across the device, the effect of changing the doping concentration in each layer and how this could be optimised for high power applications.

Using simulations, the structure was designed with a new doping profile and this design was then manufactured at Sivers Photonics and the test results are presented here showing that the new design succeeds in reducing the thermal roll-off leading to better performance though this better performance is only realised for devices operating at high currents but represents worse performance for low current operation. In the course of this study, the effect of thyristor breakdown was studied and due to the fact that a lot of the devices in the first batch were not able to reach high power due to this effect, a new design was proposed and again fabricated at Sivers Photonics which reduced this effect and was overall a success at high powers. <br><br>The second main challenge studied in this thesis is that of linewidth.