POISE (Physics of Intersubband Semiconductor Emitters) is a Marie Curie Research Training Network supported by the European Community's Sixth Framework Programme. The network contract (MRTN-CT-2004-51240) was agreed between the European Commission and the consortium on 1st October 2004, with a duration of 48 months.

The aim of the POISE network is to investigate the fundamental aspects of materials and device physics that will underpin the next generation of III-V semiconductor quantum cascade lasers and other intersubband devices. The research programme will provide the focus for over 400 months of Early Stage and Experienced Researcher training. A more detailed summary is given below, and full details can be found in Annex I of the contract.

The following Institutes are members of the Consortium:

Recent years have seen spectacular advances in the performance and functionality of quantum cascade lasers based on intersubband transitions in III-V semiconductor quantum wells.

There remain, however, a large number of relatively unexplored areas in quantum cascade laser research which offer the potential to raise performance to still higher levels, as well as shedding light on new areas of semiconductor device physics. For example, rapid non-radiative intersubband scattering by longitudinal optical (LO) phonon emission places fundamental limits on optical gain in current quantum cascade laser designs, which could potentially be overcome by reducing dimensionality by application of high magnetic fields or by novel structures exploiting semiconductor quantum dots.

Similarly, there is considerable need for a full understanding of the processes that lead to optical gain in THz quantum cascade lasers, where the intersubband separation is below the LO phonon energy. The potential for short wavelength operation would be greatly enhanced by improved knowledge of the electronic parameters of Sb-based heterostructure systems which could lead to the development of intersubband sources and modulators at telecoms wavelengths. Another exciting prospect arises from exploiting the non-linear optical properties of quantum cascade laser structures to produce a wide range of operating wavelengths by second harmonic and sum/difference frequency generation. Related studies of structures incorporating photonic crystal waveguides and/or exploiting surface plasmon effects also promise to lead to key advances in quantum cascade laser functionality.

This research training network brings together 9 European leaders in the fields of quantum cascade lasers and non-linear optics to form a coherent body of expertise which is strongly placed to investigate these fundamental areas which promise to underpin the next generation of quantum cascade lasers and other intersubband devices.

This research programme will provide the focus for over 400 months of Early Stage and Experienced Researcher training. This will provide a significant new cohort of highly skilled young scientists, equipped with the expertise to help ensure that European research continues to flourish in this highly topical and technologically significant area of semiconductor physics.