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Reference : UMR9001-ERIAKM-001
Workplace : PALAISEAU
Date of publication : Tuesday, November 17, 2020
Scientific Responsible name : Eric Akmansoy
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 15 December 2020
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
All-Dielectric Metamaterials for Zero-Index-Photonic :
Negative Index and Near-Zero Index Materials at Terahertz
Metamaterials have opened a new field in physics and engineering. Indeed, these artificial struc- tured materials give rise to unnatural fascinating phenomena such as negative index, sub-wavelength focusing and cloaking. Metamaterials also exhibit near-zero refractive index . 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 .
We consider All-Dielectric Metamaterials (ADM) which are the promising alternative to me- tallic metamaterials, because they undergo no ohmic losses and consequently benefit of low energy dissipation and because they are of simple geometry . They consist of high permittivity dielec- tric resonators involving Mie resonances. We have experimentally demonstrated negative effective permeability and/or permittivity by the means of all-dielectric metamaterials . Previously, we have also demonstrated a negative index all-dielectric metamaterial .
Metamaterials that exhibit Near-Zero Index metamaterials (NZI) have a large number of ap- plications including wavefront engineering, directivity and gain enhancement of antennas, electro- magnetic cloaking, phase matching for nonlinear applications, unidirectional transmission, defect waveguides, Zero-index Materials (ZIM) cavities, . . . 
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)”.  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. . 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 (see fig. 1) .
During this PhD thesis, All-Dielectric Metamaterials will be numerically designed; Negative Index and Near-Zero Index will be addressed. The All-Dielectric Metamaterials will also be charac- terized 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.
1. via a PhD scholarship
This work takes place within the framework of a group of scientists of different disciplines (che- mists, material scientists and physicists)  which deals with All-Dielectric Metamaterials design, hight dielectric material fabrication, structuration and characterization .
 I. Liberal and N. Engheta, “Near-zero refractive index photonics,” Nature Photonics, vol. 11, pp. 149 EP –, 03 2017.
 N. I. Zheludev and Y. S. Kivshar, “From metamaterials to metadevices,” Nat Mater, vol. 11, pp. 917–924, 11 2012.
 S. Jahani and Z. Jacob, “All-dielectric metamaterials,” Nature Nanotechnology, vol. 11, pp. 23 EP –, 01 2016.
 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.
 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.
 N. Shankhwar, Y. Kalra, Q. Li, and R. K. Sinha, “Zero-index metamaterial based all-dielectric nanoan- tenna,” AIP Advances, vol. 9, no. 3, p. 035115, 2019.
 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.
 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.
 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 me- tamaterials applications at terahertz frequencies,” Scientific Reports, vol. 8, no. 1, p. 15275, 2018.
The C2N (Center for Nanosciences and Nanotechnologies) is a joint research unit of the University of Paris Saclay and the CNRS located in Palaiseau (91). Made up of around 410 people, C2N's research themes are photonics, nanoelectronics, nanobiofluidic microsystems and materials. The agent will join the scientific photonics department.
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