M2 internship research proposal

All-Dielectric Metamaterials for Zero-Index-Photonic  :

Negative Index and Near-Zero Index Materials at Terahertz

Éric Akmansoy

Département Photonique - C2N

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General 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]. 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 [2].

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 [3]. 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 [4]. Previously, we have also demonstrated a negative index all-dielectric metamaterial [5].

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, . . . [6]

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)”. [1] Zero Index Photonics has consequently fundamental and technological implications on different subfields of optics and nanophotonics. Antennas systems and optical components 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. [7]. 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 [8].

Work Plan

During this M2 interbship, All-Dielectric Metamaterials will be numerically designed ; Negative Index and Near-Zero Index will be addressed. The All-Dielectric Metamaterials will also be characterized in the THz frequency range. In the first instance, our aim is to demonstrate near-zero index and negative index. Then antennas systems and various photonics components will be considered.

This work takes place within the framework of the DisPonT ANR project. It gathers a group of scientists of different disciplines (chemists, material scientists and physicists) [9] which deals with All-Dielectric Metamaterials design, hight dielectric material fabrication, structuration and characterization [9, 10].

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Bibliography

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

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

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

[4]  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.

[5]  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.

[6]  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.

[7]  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.

[8]  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.

[9]  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

[10] 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

poursuite en thèse envisageable

consult the offer in attached file

Neuromorphic photonics is an expanding field of research at the heart of recent progresses in analog computation and machine learning. Its goal is to investigate new ways to process optical information or to compute using brain-inspired physical concepts.

We propose to investigate the physics and applications of coupled spiking photonic nodes implementing artificial spiking neural networks. Each node (optical neuron) is materialized by a micropillar laser with integrated saturable absorber, whose neuromimetic properties have already been explored in the team. In neurons, information is coded with spikes (electrical pulses) which are excited in an all-or-none fashion provided input stimuli to the neuron soma exceed a given threshold. This generic property is called excitability and has been demonstrated in micropillar lasers with optical spikes [1]. Though, the optical spikes emitted by these latter are more than one millions times shorter in duration than biological action potentials. Hence, photonic neurons could in principle be interesting to build ultrafast artificial neural networks with low power consumption.

The objective of the internship will be to take part to the projects developed in the group to fabricate and study neuromorphic architectures, understand the physics involved in the dynamics of these coupled microlasers and demonstrate ultrafast analog computation. The work will mainly involve experimental and modeling activities, with nanofabrication aspects. The internship will take place at the C2N (Palaiseau) which hosts a first-class nanofabrication facility.

The applicant should have a background in physics, optics, laser physics, semiconductor physics. Background in semiconductor lasers and/or nonlinear dynamics and/or machine learning is appreciated but not compulsory.

Website: https://toniq.c2n.universite-paris-saclay.fr/fr/activites/smila/

Reference

[1] Micro-lasers for neuromorphic computing V. A. Pammi, S. Barbay, Photoniques 104, 26-29 (2020) https://doi.org/10.1051/photon/202010426

poursuite en thèse envisageable