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Directional power combining in photodiode-based photonic transmitters enabled by antenna arrays

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Français - Anglais

Date Limite Candidature : jeudi 22 décembre 2022

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General information

Reference : UMR6164-DAVGON-007
Workplace : RENNES
Date of publication : Thursday, November 10, 2022
Scientific Responsible name : David GONZALEZ
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 2 January 2023
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly

Description of the thesis topic

To cope with the colossal increase in data traffic, very high-speed wired (optical fibers) and wireless technologies must be developed. As for wireless communications, it is mandatory to use high frequency carriers to reach the data rates of around 100 Gbits/s foreseen for future beyond 5G networks or "6G". This thesis will explore frequency windows in the sub-THz range (100 GHz -1 THz) to achieve such high data rates in real time.

The development of new components (such as UTC photodiodes) is essential to increase the power generated in the “THz gap” and, hence, to compensate for the high free-space propagation losses in sub-THz radio links. However, an effective use of sub-THz carriers in field wireless applications (mmunications beyond 5G, imaging, etc) requires that the generated signals be transmitted only in directions in which they will be received.

To this end, narrow (very directional) and steerable beams must be generated over a sufficiently wide field of view. The two laboratories (IETR and IEMN) involved in this project will cooperate to study the integration of UTC photodiodes (IEMN) with wideband planar antenna arrays (IETR). The developed photo-mixing arrays will rely on a coherent combination of power and also enable beam-steering. Indeed, it will be possible to control the phase of each radiating element by “true time delay” and to radiate mainly in the desired direction.

The objective is the development of photonic antenna arrays whose level of performance will go beyond the current state of the art. Two complementary concepts will be explored:
• Photomixing antennas with photonic beam formers. We will explore scalable and compact network structures capable of providing conjugate matching over a wide frequency range. Some of these concepts have already been validated by simulation [1].
• Higher gain values will be obtained by combining these photomixing antennas with advanced focusing structures (e.g. lenses or transmitting gratings) [2].

The final goal will be to propose flat antenna architectures with high gain and controllable beam for high-speed communications (backhaul/fronthaul radio links).

[1] A. J. Pascual, L. E. García-Muñoz, R. Sauleau and D. González-Ovejero, “Unit-cell design for antenna arrays efficiently matched to uni-travelling-carrier photodiodes,” 44th Int. Conf. Infrared Millimeter THz Waves, Paris, France, 2019, pp. 1-2. doi: https://doi.org/10.1109/IRMMW-THz.2019.8874017.

[2] A. J. Pascual, M. Ali, T. Batté, F. Ferrero, L. Brochier, O. de Sagazan, F. van Dijk, L. E. García Muñoz, G. Carpintero Del Barrio, R. Sauleau, and D. González-Ovejero, “Photonic-enabled beam switching mm-wave antenna array,” J. Lightwave Technol., vol. 40, no. 3, pp. 632-639, 1 Feb.1, 2022. https://doi.org/10.1109/JLT.2021.3124092.

Work Context

This thesis is part of the electronics PEPR, which aims to structure the French community for applications spanning the next 10 years. In this context, it is almost established that the next "6G" will play a fundamental role in the near future.

This interdisciplinary project involves 2 CNRS laboratories:
1) IETR – UMR CNRS 6164, (www.ietr.fr), with experience on electromagnetics and antenna design.
2) IEMN – UMR CNRS 8520, (https://www.iemn.fr/en/), with expertise on THz photonics and THz electronics.

This thesis is a great opportunity to bring together two communities (antennas and THz photonics) which generally interact simply by exchanging the definition of interfaces or by giving each other specifications which sometimes ignore each other's needs. The PhD student (M.Sc. in Electrical/Electronics Engineering or Physics) will develop fast THz transmitters with high output power (IEMN) and exploit such devices for agile and efficient radiating elements (IETR). In addition, she/he will work on the manipulation of THz waves using beam-formers to control beams at the output of the antenna system). Finally, the doctoral student will contribute to antenna testing, transmitter measurement and global front-end characterization (IEMN-IETR).

Constraints and risks

Nothing to report.

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