Physics Diploma (October 1997 to March 1998)
This 18-weeks practical work (9th semester) has been conducted in the Opto- and Micro-Electronic Institute of the Physics Department under the guidance of Professor Franz-Karl Reinhart. The project was included in the thesis work of Frank Filipowitz.
Title
Fabrication and Characterization of Quantum Wires Embedded in an Optical Waveguide
Abstract
The subject of this diploma work is the electro-optical characterization of quantum wires realized with III-IV semiconductor materials and placed in the middle of an optical waveguide. These samples are p-i-n diodes produced by Molecular Beam Epitaxy and by holographic lithography.
It has been possible for the first time to study the elements of the optical matrix for the first levels of the interband transitions of quantum wires along the three orthogonal directions of the optical polarization vector. We have observed the anisotropy of the optical matrix elements by photocurrent measurements. The transmission measurements of the guided modes depending on the light frequency have provided the first values of the absorption coefficient for the fundamental level of quantum wires. We have observed an atypical behaviour of the photocurrent and no confined Stark effect has been observed when an external electrical field is applied on the structure. The re-growth interface located in the middle of the waveguide core, seems to strongly modify the electrical field distribution around the quantum wires.
Several facts indicate a lower potential for optical modulators containing quantum wires instead of quantum wells : the low absorption coefficient, the difficulty to apply an effective electrical field and the fabrication complexity.
Interesting links
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Physics department of the Swiss Federal Institute of Technology : sph.epfl.ch
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Institute of Photonics and Quantum Electronics (previously the Opto- and Micro-Electronic Institute) : imowww.epfl.ch
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Short biography of Professor F.K. Reinhart : in French
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