The Group of Semiconductor Optics headed by Prof. Dr. Wolfgang Elsäßer within the Institute for Applied Physics of Darmstadt University of Technology deals with investigations of the physics and related phenomena of semiconductor emitters and semiconductor waveguides.
The research motto of the department can be very well characterized by "Semiconductor Device Photonics and Applications". The basic idea is to have the semiconductor laser as the relevant research subject and to group around various experimental techniques in order to understand the basic physics and the interaction of the device, the photons and the carrier system with the goal to achieve better, more appropriate and new functionalities, structures and concepts for applications in photonics and metrology.
The actual research topics of the department in Darmstadt are
- Nonlinear Dynamics, i.e. investigations of instabilities and structure formation in semiconductor lasers ("Optical Chaos", coherence collapse, spatio-temporal dynamics in broad area lasers), their understanding on a very fundamental basis, and their controls
- Nonlinear Optics in passive semiconductor waveguides (surface enhanced second harmonic generation), including phase conjugation and applications
- Generation of nonclassical light with semiconductor devices and applications in photonics and metrology
- Mode locking of multisegment semiconductor lasers and research towards 100 GBits/s transmission, including modelling of pulse emission and propagation in complex semiconductor structures
- Ultrashort sub-picosecond time dynamics in active (lasers and amplifiers) and passive semiconductor waveguides (pump-probe experiments using a mode-locked 100 fs Ti:Sapphire laser as spectroscopic tool
- Investigations of Quantum Cascade Lasers (QCLs) emitting in the Mid-Infrared spectral domain
- Generation of continuous wave (CW) Terahertz radiation by photomixing of two-wavelength semiconductor based sources and by nonlinear frequency mixing processes
The broad aspects of the research activities enable an ideal training atmosphere by unifying different and highly sophisticated experimental techniques, also well supported by the research activities of the other members of the Institute of Applied Physics. The size and the organisation of the department allow an effective and stimulating discussion and group atmosphere, meetings and workshops.
A large variety of collaborations with laser and structure fabrication facilities, on either industrial, university or research institute scale exists, as well as under various funding aspects. This is due to the interdisciplinary character of the research subject in between semiconductor physics, electronic engineering and materials research, photonics application and very fundamental quantum aspects.
The department has a long tradition in international collaborations, in general (e.g. NATO collaboration) and in particular in European collaboration programs of Twinning, RACE (AQUA and WELCOME), HCM (Pico-Giga). It is well linked to national research programs from the Deutsche Forschungsgemeinschaft (DFG) and the ministry for research and technology (BMBF). Last, but not least, the technical university requires and allows at the same time, profound and excellent teaching activities, once more again, for physics as well as for engineering students.