Between 1966 and 1973 : Studies of Physics at the Universities of Marburg, Bochum, Frankfurt, München (Germany)
Master’s degree at the University of Marburg in 1970
Ph.D. degree at the University of Frankfurt / Main in 1973
Degrees in theoretical solid state physics
“Habilitation à diriger des Recherches” at the University of Strasbourg (France) in 1985
Speciality: Nonlinear optics, experimental and theoretical semiconductor physics
Non-linear optics of semiconductors. Time resolved spectroscopy of bulk semiconductor material or confined in 1 or 3 dimensions.
Activités de recherche
Study of spin relaxation processes in semiconductors
We have developed a new non-degenerate pump and probe techniques in order to access the individual spin dynamics of electrons, holes and excitons. We use the fact that optical transitions between states may be allowed or for co- or contra circularly polarized pulses. We have thus studied the exciton spin relaxation in CuCl single crystals, piezoelectric CdTe/CdMnTe quantum wells, and GaAs quantum wells.
Temporal and spectral characterization of CdZnTe quantum boxes by optical transmission and photoluminescence studies
By time resolved transmission and photoluminescence studies we investigate relaxation processes of electron-hole pairs in self-assembled CdZnTe quantum boxes, rich in cadmium, which are included in a quantum well rich in zinc. We find three different regions: First a sub-picosecond region that corresponds to the relaxation of carriers in the quantum well by emission of a phonon cascade. This region has to be described in the frame of quantum kinetics theory. During the following several tenths of picoseconds we observe the trapping of the carriers in the quantum boxes. In the end, over several hundreds of picoseconds, we measure the radiative recombination of the trapped carriers.
Optical Gain of silicon nanocrystals imbedded in a sol-gel de SiO2matrix
Silicon based nanostructures present an important interest in opto-electronics: Their luminescence is situated in the visible while the band gap of bulk silicon is indirect in the infrared spectral region. In the frame of a collaboration with the Czech Academy of Sciences we have studied the optical amplification of samples, which consist of inclusions of silicon nanocrystals in a SiO2 sol-gel matrix. Their dispersion in a transparent matrix has the advantage to increase the luminescence intensity and to stabilize the nanocrystals.
After my thesis in solid-state physics (1973), in which I have studied theoretically the interaction between phonons and magnons in Van Vleck paramagnets, I have accepted a position as assistant professor at the University of Regensburg in Germany. I have worked as a theoretical physicist on properties of excitons in semiconductors under high optical excitation conditions. After 1977, as a grant holder of the « Deutsche Forschungs Gemeinschaft » and the CNRS, I have worked in the same research field with a group of experimentalists at the « Laboratoire de Spectroscopie et d’Optique du Corps Solide » at Strasbourg. During 1980 and 1981, I was assistant professor at the University of Essen, and I have joined the CNRS on a permanent position in 1982 as a « Charge de Recherche » before I was promoted « Directeur de Recherche » in 1988. In 1993, I applied for a professorship and I became affected at the “UFR de Physique” of the “Université Louis Pasteur, Strasbourg I”.
My definite installation at Strasbourg has also changed my research activities: Being in charge of the theoretical aspects of our research before 1982, it was also necessary to have a good knowledge of its experimental aspects. I was very interested by this implication and I began to participate actively in the experimental work. In this context, I have studied the dynamics of the renormalisation of the dielectric function under high resonant optical excitation and non-linear optics of semiconductors in general.