Modelling and Design of Advanced High Speed Vertical Cavity Semiconductor Lasers

Vertical-cavity surface-emitting laser (VCSEL) constructions capable of direct modulation at bit rates in excess of 40 GBit/s have attracted considerable attention for future high speed long- and medium-haul networks. The two main approaches to realising this goal are, firstly, the improvement in the direct current modulation laser performance, with 40 GBit/s direct modulation having been demonstrated recently, and, secondly, using advanced modulation schemes. These, in turn, fall into two major categories: firstly, modulation of the photon lifetime in the cavity as an alternative to current modulation, and, secondly, current modulation enhanced by photon-photon resonance in a specialised laser structure (e.g. using an external cavity [1], or a laser array [2]). Theoretical models describing both of these solutions have been developed, but appear to have certain limitations which will be discussed later in the thesis, and no systematic analysis and comparison of modulation properties of advanced modulation scheme had been performed, to the best of my knowledge. This was the purpose of my PhD project.
In order to understand the performance of the photon lifetime modulation for Compound Vertical Cavity Surface Emitting Semiconductor Lasers more accurately, a model involving careful analysis of both amplitude and frequency (phase) of laser emission, as well as the spectrally selective nature of the laser cavity, is required. We have developed such a model and used it to describe the laser operation and predict the performance beyond current experimental conditions in both large and small signal modulation regimes for the first time according to our knowledge.
Finally, we studied the alternative method of ultrafast modulation of VCSELs, consisting of current modulation enhanced by photon-photon resonance. The analysis concentrates on the version of the method involving an in-plane integrated extended cavity. A new model is developed to overcome the limitations of existing models and to allow better understanding of the dynamic of the in-plane laser cavity.