Seminars Archive

Unipolar injection semiconductor lasers. A new GaAs based technology for the generation of mid-infrared radiation

Abstract
The quantum cascade (QC) laser is an excellent example of how quantum engineering can be used to design and develop new laser materials in the mid-IR. By controlling the quantum well width and the tunnelling barrier thickness it is possible to create artificial potentials where level separations, dipole matrix elements, lifetimes and scattering times are mainly dependent on the potential design. This allows one to conceive new materials (materials by design) in which the electronic and optical properties can be tailored not only to demonstrate new physical effects, but also to optimise device performance. Recently we demonstrated for the first time laser action in QC structures made of GaAs/Al(x)Ga(1-x)As. The use of this material gives additional technological value to QC lasers since GaAs technology - based on the most widespread and lowest-cost of all III-V compound semiconductors - currently represents more than 90% of the world-wide market for semiconductor lasers in terms of units produced. We will review the major points in the design of QC lasers and finally give an overview on present laser performance.