The theory of the lateral current injection (LCI) laser is developed for the first time. LCI laser fabrication technologies are studied, improved, and deployed in experimental trials. The first LCI laser at 1.5 [mu]m formed by ion implantation is reported. The first LCI laser at 1.5 [mu]m formed by epitaxial regrowth and dopant diffusion is reported. Full characterization and analysis of these structures in the light of the new theory yield further insight into laser operation.

The limitations and constraints imposed by vertical injection of carriers in semiconductor lasers motivate this work. The vertical injection paradigm is set aside, and a new degree of freedom—the lateral dimension—is explored. The release of the lateral direction is seen to enable monolithic optoelectronic integration and novel functional optoelectronic devices.

Previous LCI laser attempts were empirical and, as such, provided little insight into the nature and potential of the lateral injection paradigm. In this work, a first-principles approach is used to shed light on the essential physical mechanisms which underlie LCI laser operation. The physical model developed systematically herein is used to explain observed device performance and inspire new design methodologies.

Experimental explorations are undertaken with a view to probing further the operation and fabrication of the LCI laser. Process technologies are studied and assessed critically, and are then developed and deployed in experimental trials. The resulting devices are characterized electrically, optically, and thermally. The theoretical model which underpins this work provides a new basis for explaining observed behaviour and evaluating new device concepts.

In addition to developing from first principles and validating experimentally the first physical model of the LCI laser, a number of specific original contributions are made:​ the self-consistent evolution of carrier density and lasing modes is explained;​ the role of lateral heterobarriers in confining carriers is quantified;​ and the central role of active region differential resistance in governing LCI laser performance is revealed.

The field of photonics is seen to abound with promising new directions which may be opened up by the release of the lateral dimension. The transformation wrought in electronics by the emergence of the planar transistor points to an auspicious outlook for lateral injection. This work paves the way.