Photonics, plasmonics, metasurfaces

We study the interaction of light with nanostructured metallic and dielectric metasurfaces. These surfaces enable arbitrary manipulation of the light wavefront and polarization, and have different functionalities like nanometer flat lenses, polarization filters etc.

Surfaces for strong diffraction

Near field interaction of electromagnetic multipoles excited by impinging light on submicrometer Si particles can lead to light wavefront manipulation. Light passing from designed sphere metagratings with thickness around half the wavelength can experience strong diffraction to large angles up to 70 deg with close to 70% efficiency. 

Large angle diffraction, tailored light emission, or strong light absorption can be designed.

Large angle diffraction from Si sphere metagratings. (a) Structure, (b) Transmission of different diffraction orders, (c) Electric field close to 735 nm.

Nanopaterned surfaces for total absorption

By means of full electrodynamic calculations we investigate structures that can totally absorb light, minimizing all reflections. Such efficient absorbers of visible and infrared light are useful in photovoltaic and sensor applications. Perfect absorption is predicted in metallic sphere arrays, but also for silicon spheres on a reflecting substrate.

(a) Periodic array of spheres on a metallic substrate separated by a thin dielectric spacer. (b) Periodic array of spheres on top of a multilayer dielectric (Bragg) mirror. (c) profile of the electric field intensity at the total absorbing resonance of structure (a).

Designing photonic structures of nanosphere arrays on reflectors for total absorption, E. Almpanis and N. Papanikolaou, Journal of Applied Physics 114(8), 083106 (2013).

Comparison of Ag and Si nanoparticle arrays: mimicking subwavelength plasmonic field concentrations with dielectric components, E. Almpanis and N Papanikolaou, Journal of the Optical Society of America B 33 (1), 99-104 (2016).
Dielectric nanopatterned surfaces for subwavelength light localization and sensing applications, E. Almpanis and N Papanikolaou, Microelectronics Engineering, 159, 60-63 (2016).

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