Welcome on the

I continue my studies in Zurich and I pass the final exam in fall 1996. Afterward I finish my studies with a dissertation (The "Diplomarbeit" is required for the final graduation) at the Institute of Communication. The chosen topic of my work is the fractal compression of pictures.

I make a Ph.D. thesis at the École Nationale Supérieure des Télécommunications (ENST) in Paris (Paris,France). During four years I am working on the electro-optic probing of integrated circuits. I am measuring the electric field in a GaAs device with a laser beam. (See Research for details).

I do the mandatory trainee ship in a work shop of Bell Escher Wyss at Kriens (Lucerne, Switzerland). I get in touch with metal processing and the construction of water turbines.

During my second trainee ship, I am working for the Swiss Aircraft and System Company in Emmen (Lucerne, Switzerland). I am developing software for a simulator, I am setting up a data base with Microsoft-Access and I am testing some an Altera EPROM device.

With the support of IEASTE Switzerland (International Association for the Exchange of Students for Technical Experience) I get a job as a trainee or technical assistant at the physics department of the Queen's University in Kingston (Ontario,Canada). During one year I am developing data acquisition devices for the testing of concrete pressure pipes. Afterward I am analyzing the data with Wavelets.

Problem

Recently, the number of microwave applications increased with the evolution of new telecommunication techniques and hence the use of Microwave Monolithic Integrated Circuits (MMIC) made of Gallium Arsenide (GaAs). This special kind of integrated device consists of microwave guides, capacitances, resistors, inductance and transistors (see picture) on the GaAs substrate and is typically operated at frequencies between 1 and 10 GHz. For the further development of MMIC, it is important to have characterization tools at your's disposal to examine the processes inside the integrated device.

Work

The aim of my Ph.D. thesis was to develop respectively to improve an existing tool to probe the electrical signals inside the MMIC. The basic idea is to exploit the electro-optic properties of GaAs: We focus a laser beam with a wavelength of 1550 nm onto the device under test (see picture). Considering that GaAs is transparent for this wavelength, the beam will enter the device and will be reflected from the back face. The refractive index of GaAs is changing in function of the surrounding electric field and hence in function of the seeked microwave signal. So the reflected laser beam is modulated due to the Pockels effect. We can measure this modulation and by means of a calibration procedure, we can determine the absolute value of the electric field inside the IC.

Publications

• Philipp Olivier Müller, Stefan Lauffenburger, Didier Erasme and Bernard Huyart:"Système fibré de sondage électro-optique des Circuits Intégrés Hyperfréquence" JOURNÉES NATIONALES D'OPTIQUE GUIDÉE, Limoges 1999.
  

• Didier Erasme, Stefan Lauffenburger and Bernard Huyart: A all fibered measurement design for CW calibrated MMICs electro optic probing" Terahertz and Gigahertz Electronics and Photonics II, SPIE INTERNATIONAL SYMPOSIUM, 2000.
  

• Thesis Stefan Lauffenburger: Characterization of microwave Gallium Arsenide integrated circuits with electro-optic probing using a continuous laser beam, ENST 2003.