Dynamical properties of bistable systems under the influence of noise & feedback

The dynamical properties of semiconductor lasers under the influence of optical feedback have been the subject of numerous studies. It is now well know that feedback can be use to narrow the laser linewidth but can also induce self-pulsation and coherence collapse.

Dynamics of Semiconductor Lasers

Semiconductor lasers have many interesting dynamical features. For example, these devices have a strong phase amplitude compling and the modulation of the injection current leads to frequency modulation. We analyse the dynamical properties of semiconductor lasers for applications such as directly modulated semiconductor lasers but we also study non-linear dynamics using these lasers

Broad Area Semiconductor Lasers

The extension of the transverse section is a possible solution to increase the output power of semiconductor lasers. However, the strong phase-amplitude coupling, characteristic of semiconductor materials, leads to the appearance of multimode behaviour and optical filaments. The aim of our research is to design devices that can achieve high power and high brightness.

Quantum Dot Devices

Quantum dots are man made nano structures that typically vary in size from 10's to 100's of nanometers, that are fabricated in semiconductor heterostructure wafers. Since these dimensions are on the order of the De Broglie wavelength of the electron, the electron momentum is quantised as in an atomic system. As a consequence, the optical emission spectrum displays features characteristic of atomic or molecular media. In our group, we analyse the properties of GaAs substrate based quantum dot semiconductor lasers. These devices are extremely interesting as they will provide a low cost alternative to InP lasers that are cureently used for fibre telecommunications at 1310 nm and 1550 nm.