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Soutenance de thèse

Vendredi 23 juin à 14h00,
Salle Nevill Mott, D420

Orateur : Dmitrii TUMANOV
"Actuation and motion detection of different micro- and nanostructures"

Abstract

This thesis is related to the field of opto-mechanics and the use of different techniques for the measurement and manipulation of mechanical properties of nano-structures.

First part of the work is dedicated to the photonic wires. These objects are GaAs structures with an inverted conical shape of length of the order of 10 µm and diameter of less than 1 µm, containing a layer of InAs quantum dots inside. Wide-range static stress-tuning of quantum dots photoluminescence spectrum was demonstrated using nano-manipulators to bend the wires. Additionally, owing to the spatial dependence of the spectral shift, this technique offers the possibility of QD positions mapping.

The second part of this work concerns the optical actuation of these photonic wires. A laser beam focused on the wire and modulated at the mechanical resonance frequency can set the wire in motion. The physical mechanisms responsible for these effects are presented and discussed.

In the third part is presented a method enabling the detection of mechanical oscillations of small (less than 50 nm in diameter) nanowires with the use of a Scanning Electron Microscope. This original method offers a possibility to detect the motion of many types of micro- and nanoelectromechanical devices which are too small to be detected optically owing to light diffraction limit. Moreover, this method also affects the mechanical properties of the structures via a back-action force that becomes non-negligible for such small devices. It opens up the possibility for further fundamental studies related to cooling of the mechanical motion.

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