PhD Defense of Léo HETIER

Abstract :
Several advance systems such as Next Wireless communication system, spectroscopes and Radars require high purity radio frequency signals. Using electrical devices, the generation can easily be realized for frequency lower than millimetre waves (30GHz). Nevertheless, the performances of such electronics based system degrade while increasing the frequency. Optical source for radio frequency generation is a well-known strategy to access very high frequencies, up to the THz range. Unfortunately, such optical systems usually rely on control loops that either limit the maximum frequency or require complex systems to operate. Recent works in our laboratory demonstrate the capabilities of the ion exchange technology to produce lasers on glass having state-of-the-art spectral properties suitable for frequency generation. We recently validated their use in a radio-over-fiber communication system to generate 60 GHz radio frequency carriers, in a wireless communications context. Our objectives are the improvement of the structure and the extension of their applications to reach higher frequencies (0,3-1 THz). These studies will be conducted in collaboration with research teams specialized in THz applications for spectroscopy (IMEP-LaHC-Chambéry) and/or Communication (IES-Montpellier). Expected work: - Laser conception and realization : In order to achieve excellent spectral properties, the optical sources used for heterodyning need to be co-integrated in the same glass substrate. This work will benefit from previous studies. We will focus on optimization of the design and realization of advanced co-integrated lasers. It will imply working in a clean-room environment, laser conception, realization and characterization. - Advanced characterizations : In order to understand laser behaviour and to qualify the radio frequency generated, several characterization experiments will be implemented, especially focused on phase and frequency noise analysis of both the optical and electrical signal generated. This part of the work may benefit from collaborations already initiated. - Advanced designs: The integration of additional features will be investigated in order to extend the capabilities of these systems. Apart from additional optical functions, the encapsulation of the structure and the co-development of active and passive functionalities will improve the system durability and facilitate handling required for collaborations.