Background

The terahertz (Thz) and mid infra red (MIR) ranges of the electromagnetic spectrum are under used in comparison with others, but the potential for application is huge. In particular such frequencies could be used for medical or security scanning and short range high volume wireless data transmission.

The main blockages to development of such applications are the technical difficulties and high costs involved in generating high intensity THz and MIR radiation. Quantum cascade lasers (QCLs) are one possible solution to this. The main challenge with QCLs are the high complexity of the structure, which results in very high development costs for new QCL wafers, and the need to cryo-cool them for operation, using liquid nitrogen.

The technology

The QCL expertise at Sheffield Hallam University involves theoretical modelling. There are three aspects to the intellectual property (IP), firstly, a QCL simulator has been developed, which accurately predicts the behaviour of QCL designs. Secondly, a method of producing lasing at room temperatures has been designed (optical pumping). And thirdly, a method of producing lasing without polar inversion (LWPI) has been created.

The simulator package involves highly complex mathematics, algorithms and software, and the IP is effectively protected by this. The optical pumping and LWPI techniques are the subject of UK patent applications.

Benefits

The QCL simulator produces accurate predictions of current for new configurations of QCL wafers and errors of between 5 per cent and 10 per cent are seen. This will allow multiple variations of structures to be simulated without the high expense of using repeated molecular beam epitaxy (MBE) growth. Potential savings in the development of a new QCL wafer structure could be up to six figures.

The optical pumping technique will potentially allow QCLs to produce high intensity lasing output at room temperature, removing the need to use liquid nitrogen and cryo-cooling systems, thereby reducing product costs significantly.

Development stage

Development and project partners are required for the pending patents. The QCL simulator is used as a consulting tool, simulation runs and packages of simulations are available on request.

Lead researcher(s)

Professor Mauro Pereira