[PhD Subject] "Light confinement in photonic moiré"


In the field of Nanophotonics, we exploit technological advances to structure matter at the nanoscale to control different parameters of photons in wavelength-scale objects. This approach has been very popular over the last twenty years and has led to major advances in many fields of application such as information technology, sensors for health and the environment or energy production.

Moiré patterns are superlattice structures that appear when two gratings (with a different orientation or period) are superimposed. This phenomenon, well known in classical optics, has been recently exploited in the field of condensed matter. In particular, fascinating effects are expected when the moiré effect is obtained from two superposed and twisted graphene sheets: depending on the angle formed by the sheets, studies show that the electron transport can be completely modified and lead to a superconductivity phenomenon for "magic" angles. In the field of nanophotonics, equally amazing effects are expected from moirés formed by the superposition of photonic crystals membrane.

Emblematic objects of nanophotonics, photonic crystal-based structures are now a well-known platform to control the properties of light such as the ultimate confinement of electromagnetic energy, the propagation speed of photons, and non-linearity.

The i-Lum team at INL has a well-established expertise in this field. In particular, INL researchers have recently demonstrated that, in photonic crystals, the exploitation of symmetry breaking, also present in moiré crystals, enables shaping at will the dispersion relation of photons, thus opening the way to an unequalled control of optical densities of states.

Thesis Objectives

The main objective of this thesis is to develop and implement the concepts of photonic moirés to fabricate superlattices of micro-resonators in which photons can be efficiently "stored". These super-arrays can be used to form resonant cavities for new light sources (large area single mode lasers for example).

This objective will be achieved through the realization of periodic or aperiodic structures, of the "moirés" type, composed of two coupled photonic crystals, shifted, "tilted" or with slightly different periods.

Research program and proposed scientific approach

The PhD student will be hosted in the i-Lum team of the INL. A first part of the thesis will be devoted to the bibliographic study, the comprehension of the photonic concepts, as well as the training on various experimental tools crucial for the project. Then the PhD student will specifically be in charge of optimizing the various technological stages necessary to the fabrication of the moiré structures. He/she will test and evaluate the different 3D fabrication methods in order to select the one(s) that will allow to obtain functional photonic structures. This evaluation will involve optical characterization of the structures, both in the far and near field, on various optical setups available in the laboratory. The PhD student will be able to rely on the recognized expertise of the i-Lum team in the field of photonic crystal-based structures, as well as on the Nanolyon technology platform.

The candidate

The candidate must have a strong background in material science and/or electromagnetism, with a strong motivation for technological and experimental work.

Download the full presentation of the proposed thesis and the application procedure

The deadline for applications is 18 May 2021