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 programmable circuits, LIDARs or spatial light modulators (SLMs), which allow, among other things, optical computing, remote sensing and beam shaping. Most of these devices rely on thermo-optical effects, mechanically operated mirrors or liquid crystals, which fundamentally limits their operating speeds, sizes and integrability. As these components become crucial for self-driving cars, neuromorphic computing 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 position, we propose to use the potential of phase change materials (PCMs) to dynamically control the optoelectronic response of photonic devices. More specifically, we will use chalcogenide-type materials such as GeSbTe, Sb2S3 and Sb2Se3, 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.
Our overall goal is to develop the selective electrical addressing of individual pixel elements of a nanophotonic device 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 optical computing, beam shaping and holographic display.
This PhD project therefore aims to unlock the following scientific roadblocks: (i) Investigate the -- currently poorly understood -- thermal properties of PCMs; (ii) design efficient integrated micro-heaters on-chip using multiphysics modelling; (iii) Fabricate and characterize PCM-based devices whose phase is electrically-controlled via integrated micro-heaters, towards beam-shaping and optical computing metasurfaces.
Expected original contributions:
Controlling the individual state of each PCM-based pixels will enable real-time programmable photonic circuits or on-demand writing of metasurfaces for applications ranging from holographic displays to optical computing. 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. Integrated reconfiguration techniques based on the selective control of PCM-based elements via electrical pulses 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 new reconfigurable photonic neural networks.
The candidate will take advantage of the stimulating scientific environment of INL, as well as of the scientific and technological facilities available in the lab, hosted in particular by the Nanolyon technology platform.

The candidate must have a strong background in Materials science, electrical engineering and photonics, with a strong motivation for Multiphysics designs, technological and experimental work as well as good social skills to carry out her/his researches in a dense collaborative context. The candidate 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.

Work Context

The Institut des Nanotechnologies de Lyon (INL) aims to develop multidisciplinary technological research in the field of micro and nanotechnologies and their applications. The research carried out ranges from materials to systems. The laboratory is supported by Lyon's NanoLyon technology platform.
The areas of application cover major economic sectors: the semiconductor industry, information technologies, life and health technologies, energy and the environment.
The laboratory is multi-site, with locations on the Ecully and Lyon-Tech La Doua campuses. It employs around 200 people, including 121 permanent staff. The INL is a major player in the Research and Teaching Cluster.
This position is located in an innovative environment, at the cutting edge of future technologies, in strategic application sectors.

The position is located in a sector under the protection of scientific and technical potential (PPST), and therefore requires, in accordance with the regulations, that your arrival is authorized by the competent authority of the MESR.