(See attached .pdf file)

Centre de Nanosciences et Nanotechnologies

 UMR 9001 du CNRS – Université Paris-Saclay

10 bd Thomas Gobert – 91 120 Palaiseau – France      

M2 internship research proposal

 All-Dielectric Metamaterials for Zero-Index-Photonic  : Negative Index and Near-Zero Index Materials at Terahertz

 Éric Akmansoy

Département Photonique

________________

Scientific framework

Metamaterials have opened a new field in physics and engineering. Indeed, these artificial structured materials give rise to unnatural fascinating phenomena such as negative index, sub-wavelength focusing and cloaking. Metamaterials also exhibit near-zero refractive index. [1, 2] These open a broad range of applications, from the microwave to the optical frequency domain. Metamaterials have now evolved towards the implementation of optical components. [3]

We consider All-Dielectric Metamaterials (ADM), which are the promising alternative to metallic metamaterials, because they undergo no ohmic losses and consequently benefit of low energy dissipation, and because they are of simple geometry. [4] They consist of high permittivity dielectric resonators involving Mie resonances. We have experimentally demonstrated negative effective permeability and/or permittivity by the means of all-dielectric metamaterials. [5] Previously, we have also demonstrated a negative index all-dielectric metamaterial. [6]

Metamaterials that exhibit Near-Zero Index metamaterials (NZI) have a large number of applications including wavefront engineering, directivity and gain enhancement of antennas, electromagnetic cloaking, phase matching for nonlinear applications, unidirectional transmission, defect waveguides, Zero-index Materials (ZIM) cavities. [7]

The main feature of Zero Index Materials is that the phase distribution of the EM field is nearly constant, because of the decoupling of the electric and the magnetic fields, that results in the “decoupling of the “spatial” (wavelength) and the “temporal” (frequency)”. [2] Zero Index Photonics has consequently fundamental and technological implications on different subfields of optics and nanophotonics. Optical components and antennas systems operating in the terahertz range are the targeted devices.

Recently, we have numerically demonstrated a metadevice, namely, a metalens that focuses an incident plane wave and is less than one and a half wavelength thick. Its focal length is only a few wavelengths and the spot in the focal plane is diffraction-limited. [8] We have also addressed the role of the coupling of the modes of Mie resonances in an all-dielectric metamaterial so as to achieve negative index and Near-Zero Index at terahertz frequencies. [9]

General framework and work Plan

This work takes place within the framework of the DisPoNT ANR ASTRID project. It gathers a group of scientists of different disciplines (chemists, material scientists and physicists), who deal with All-Dielectric Metamaterials design, hight dielectric material fabrication, structuration and characterization [10-12] 

During this research project, All-Dielectric Metamaterials and Metadevices will be numerically designed ; Negative Index and Near-Zero Index will be addressed. In the first instance, our aim is to demonstrate near-zero index and negative index. The role of the coupling between the modes will be investigated. Then “metadevices” (e.g., Graded Index Lens based on a metasurface 2D metamaterial) could be considered

(see attached .pdf file)

Fig. 1: (left) Negative index from an ADM (shaded area)[9], (center) Mode coupling : frequency of the first two modes of Mie resonances as a function of the distance  between the two resonators ; frequency degeneracy is observed [9] ; (right) PMMA mould fabricated by the LIGA process (Lab. Albert Fert) 

________________________

Bibliography

[1]  Iñigo Liberal and Nader Engheta, "Zero-Index Platforms : Where Light Defies Geometry", https://www.optica-opn.org/home/articles/volume_27/july_august_2016/features/zero-index_platforms_where_light_defies_geometry/

[2]  I. Liberal and N. Engheta, “Near-zero refractive index photonics,” Nature Photonics, vol. 11, pp. 149 EP –, 03 2017.

[3]  N. I. Zheludev and Y. S. Kivshar, “From metamaterials to metadevices,” Nat Mater, vol. 11, pp. 917–924, 11 2012.

[4]  S. Jahani and Z. Jacob, “All-dielectric metamaterials,” Nature Nanotechnology, vol. 11, pp. 23 EP –, 01 2016.

[5]  T. Lepetit, E. Akmansoy, and J.-P. Ganne, “Experimental evidence of resonant effective permittivity in a dielectric metamaterial,” Journal of Applied Physics, vol. 109, no. 2, p. 023115, 2011.

[6]  T. Lepetit, É. Akmansoy, and J.-P. Ganne, “Experimental measurement of negative index in an all-dielectric metamaterial,” Applied Physics Letters, vol. 95, no. 12, p. 121101, 2009.

[7]  N. Shankhwar, Y. Kalra, Q. Li, and R. K. Sinha, “Zero-index metamaterial based all-dielectric nanoantenna,” AIP Advances, vol. 9, no. 3, p. 035115, 2019.

[8]  F. Gaufillet, S. Marcellin, and E. Akmansoy, “Dielectric metamaterial-based gradient index lens in the terahertz frequency range,” IEEE J Sel Top Quant, vol. 10. 1109/JSTQE. 2016. 2633825, 2017.

[9]  Akmansoy, Eric and Marcellin, Simon, “Negative index and mode coupling in all-dielectric metamaterials at terahertz frequencies,” EPJ Appl. Metamat., vol. 5, p. 10, 2018.

[10]  C. Dupas, S. Guillemet-Fritsch, P.-M. Geffroy, T. Chartier, M. Baillergeau, J. Mangeney, J.-F. Roux, J.-P. Ganne, S. Marcellin, A. Degiron, and É. Akmansoy, “High permittivity processed SrTiO3 for metamaterials applications at terahertz frequencies,” Scientific Reports, vol. 8, no. 1, p. 15275, 2018

[11] Djemmah, Djihad Amina and Geffroy, Pierre-Marie and Chartier, Thierry and Roux, Jean-François and Bouamrane, Fayçal and Akmansoy, Éric. "Processing High Permittivity TiO2 for All-Dielectric Metamaterials Applications at Terahertz Frequencies" , Proceedings of the Sixth International Symposium on Dielectric Materials and Applications (ISyDMA’6), pp. 177–183, 2022

[12] Djihad Amina Djemmah, Delphine Gourdonnaud, Pierre-Marie Geffroy, JeanFrançois Roux, Fayçal Bouamrane, Éric Akmansoy, "From bulk toward micro-structured TiO2 ceramics for All-Dielectric Metamaterials at terahertz frequencies", 18th European Conference on Antennas and Propagation (EUCAP2024), 17-22 March 2024 Glasgow, Scotland  

poursuite en thèse envisageable

Scientific project:

The photovoltaic technology is largely dominated by silicon devices (≈ 90% of the market), which present very limited progress margins today, with an efficiency intrinsically limited below 30%. It is largely agreed that the next device generation will combine several materials, beyond silicon alone. We are developing an innovating technology, to produce solar cells based on III-V materials, already presenting high efficiencies (up to 46% under concentration), with significant cost reductions.

Our strategy is to recycle the III-V substrates, which represent the largest device cost share, for several epitaxial growths. To do so, we are developing innovative processes to modify the substrate surface, so that the fabricated layers can be easily detached, leaving a surface compatible with subsequent growths. A promising route recently suggested consist in transferring a graphene layer before performing the epitaxy, as displayed in the attached file. I was shown that the graphene permits the fabrication of a monocrystalline material, while allowing its exfoliation. Developing this method requires exploring fundamental physical phenomena as well as defining practical methodologies.

The intern will work on the development of the process as well as on the characterization of the obtained structures and intermediate products. He / she will propose further developments of the techniques already existing at the laboratory, as well as suggest the exploration of new methods. He / she will propose models to explain the observed phenomena, and design experiments for their validation. To complete those tasks, the intern will use his own knowledge as well as the scientific literature. The intern will take advantage of a unique collection of fabrication and characterization methods (XPS, TEM, SEM, luminescence) available in partner laboratories. This environment will provide various opportunities to tackle this project challenge and gain experience.

Profile:

The candidate must possess solid knowledges in material physics, characterization, and fabrication processes in a clean room environment. He / she must show good project management skills, for the development of technological procedures involving numerous parameters. He / she will be able to work independently and suggest innovative solutions to reach the project objectives. Collaborative work being at the core of the program, communication skills are required for team working as well as regular presentation of work progress in internal meetings.

Starting date: from 01/02/2025 (adjustable)

Duration: 6 months

This internship can be followed by a PhD.

Websites: https://sunlit-team.eu

poursuite en thèse envisageable