Développement d’un émetteur-récepteur térahertz (THz) ultra-compact pour des applications d’imagerie en réflexion

Abstract

The frequency band between 0.1 THz and 10 THz named terahertz (THz) is an electromagnetic frequency band between the microwaves and infrared bands. Those waves became an important research and development field for twenty years because of its unique properties for imaging, spectroscopy and communication. To push the development of those waves for industrial applications, the development of more intense sources, sensitive detectors and compact systems allowing the integration of this technology is required. This work aims at the development of a new compact system for reflective imaging of the surface of a sample. The developed system proposes a setup made of an ultra-thin emitter on a previously developed detector for THz microscopy applications. The proposed compact emitter/detector system allows to reduce the complexity of the setup required for amorphous samples. The document begins with a literature review of the THz research field. A review of the common generation and detection methods are presented and compared in terms of efficiency and applications. The review then covers the necessary setups and tools used for the detection of those waves. Finally, this section presents the state of the art of THz imaging using the different emitters and detectors presented previously. The second section of the document presents the manufacturing methods and the different optical setups of the new emitter/detector system. The different conception steps are presented as well as different generations and detection tests compared with known methods of the literature. A supplementary section was added to present the development of an electromagnet for the modulation of the THz emitter of the system. The results of the different experiments and a discussion of those results are presented in the third section of the document. This section covers the same steps as the previous section to develop and evaluate the behaviour of the new system. A fourth section was added to present an article submitted for publication after the development of the emitter/detector system. This article presents two new methods to optimize the generation of a spintronic THz emitter. Those presented methods rely on the thermal relaxation of the emitter in order to increase its saturation limit. Finally, the memoir ends with a conclusion chapter of the different results and experiments conducted. Some recommendations of improvement of the system and perspectives of continuity of the project are also presented.

Date	15 Aug 2024
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	François Blanchard (Supervisor)