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Reference : UMR5270-SYLGON-024
Workplace : ECULLY
Date of publication : Thursday, June 3, 2021
Scientific Responsible name : Sébastien CUEFF
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 September 2021
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
Nanophotonics is a mature field of research enabling the control of light via the nanostructuration of matter, with industrial applications ranging from telecoms to sensors as well as clean energy. Many optical components require local control of the direction, magnitude or phase of the electromagnetic field. This is particularly the case for LIDARs or spatial light modulators (SLMs), which allow, among other things, remote sensing and beam shaping. Most of these devices rely on mechanically operated mirrors or liquid crystals, which fundamentally limits their operating speeds, sizes and integrability. As these components become crucial for self-driving cars, head-up displays or adaptive optics, it is necessary to transform them towards on-chip integration and mass production, which means finding new integrated optical modulation strategies.
In this PhD research we propose to use the potential of phase change materials (PCMs) to dynamically control the optoelectronic response of photonic devices. For this, we will use chalcogenide-type materials such as GeSbTe, whose atomic arrangement can be changed in a controlled manner by an optical or electrical signal. This reversible amorphous-crystalline transition results in a very wide modulation of the refractive index, especially at near infrared wavelengths.
By spatially arranging specifically designed nano-elements, it is possible to create flat, nanometric devices - metasurfaces - with a great potential for optical wavefront shaping. Our overall goal is to develop the selective addressing of individual pixel elements composing a metasurface to actively write, erase and reconfigure integrated nano-devices in real time. For this it is necessary to develop a functional low-loss integrated PCM platform for photonics, with potential applications for beam shaping and holographic display.
This thesis therefore aims to unlock the following scientific roadblocks: (i) precisely characterize the optical and structural properties of various emerging thin-film PCMs in their different states; (ii) Develop methods to induce phase changes in PCMs by optical and electrical means; (iii) Develop the nanofabrication of photonic components based on PCMs.
Expected original contributions:
Controlling the individual state of each PCM-based pixel will enable on-demand writing of metasurfaces for applications ranging from holographic displays to adaptive optics. Unlike existing solutions at the micrometric scale (liquid crystals, micro-mirrors, etc.), phase change materials will allow working at the nanometric scale with a much higher speed. During this project, we will develop integrated reconfiguration techniques based on the selective control of meta-atoms based on PCMs, via optical or electrical pulses. This may lead to a breakthrough in the field of reconfigurable photonics, promising innovative devices such as compact LiDARs for autonomous vehicles, components for beam shaping for biological analysis or even new types of displays for the augmented / virtual reality.
The proposed PhD is part of the French ANR project “MetaOnDemand”. The work will be carried at INL (Lyon Institute for Nanotechnologies), located on both sites: at Ecole Centrale de Lyon in Ecully, and at INSA Lyon on Lyon-Tech La Doua, Villeurbanne. INL has an internationally recognized expertise in the design, fabrication and characterization of photonic materials and devices. The PhD will take advantage of the stimulating scientific environment of INL, as well as of the scientific and technological facilities available in the lab, host in particular by the Nanolyon technology platform.
The candidate must have a strong background in Materials science and photonics, with a strong motivation for technological and experimental work as well as good social skills to carry out her/his researches in a dense collaborative context.
The doctoral student will receive a solid training in nanofabrication in a clean room environment. Likewise, he / she will develop skills in electro-optical characterizations of nanophotonic devices. These skills acquired during the thesis will allow him to pursue an academic career, or to work in industry (microelectronics, R&D, engineering and management).
- “Dynamic control of light emission faster than the lifetime limit using VO2 phase-change”,
S. Cueff, D. Li, Y. Zhou, F. J. Wong, J. A. Kurvits, S. Ramanathan, and R. Zia.
Nature communications 6 (2015)
- “Reconfigurable Flat Optics with Programmable Reflection Amplitude Using Lithography-Free Phase-Change Materials Ultra-Thin Films”,
S. Cueff, A. Taute, A. Bourgade, J. Lumeau, S. Monfray, Q. Song, P. Genevet, B. Devif, X. Letartre and L. Berguiga
Advanced Optical Materials 9, 2001291 (2021)
- “Multipolar resonances with designer tunability using VO2 phase-change materials”
J. John, Y. Gutierrez, Z. Zhang, H. Karl, S. Ramanathan, R. Orobtchouk, F. Moreno, and S. Cueff
Physical Review Applied 13, 044053 (2020)
- “Recent advances in planar optics: from plasmonic to dielectric metasurfaces”
P. Genevet, F. Capasso, F. Aieta, M. Khorasaninejad, and R. Devlin
Optica 4, 139-152 (2017)
- “VO2 Nanophotonics”,
S. Cueff, J. John, Z. Zhang, J. Parra, J. Sun, R. Orobtchouk, S. Ramanathan and P. Sanchis
APL Photonics 5, 110901 (2020)
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