The increasing importance of infrared laser spectroscopy for gas sensing applications such as pollution monitoring or chemical process control requests the development of cheap and reliable semiconductor infrared laser sources. With the recent advent of a new class of unipolar semiconductor infrared lasers (the so-called Quantum Cascade lasers), laser devices based on III-V semiconductor quantum structures with output powers up to 200 mW operating at room temperature and covering the wavelength range between 4 5m and 11 5m, have been realized.
The purpose of the present proposal is to improve the operation of unipolar semiconductor lasers by introducing concepts for active current and wavelength control. More specifically the unipolar nature of the QC laser will be exploited by adding a third contact acting as a gate. This additional electrode will allow to actively control the size and shape of the active region. Moreover standard lithography will be used to define patterns such as gratings for surface emission or Bragg mirrors for the design of microcavities. For the applicant the project offers wide training and education in an important field of semiconductor physics as well as optoelectronics. In addition the project will greatly benefit from the advice and infrastructure at the host institution.