Giampiero Gerini

POSITION: PROFESSOR | MATERIAL ENGINEERING FROM MICROWAVES TO OPTICS

TNO UNIT: INDUSTRY (OPTICS)

UNIVERSITY: TU EINDHOVEN (ELECTRICAL ENGINEERING)

TNO LOCATION: DELFT – STIELTJESWEG

EMAIL: [email protected]

TEL: +31888664188

Research area

Metasurfaces and Metamaterials

Metamaterials and metasurfaces are artificially engineered structures consisting of arrays of sub-wavelength scatterers embedded or deposited on a host material. While in metamaterials the scatterers alter the host material electrical parameters, realizing values not available in nature, in metasurfaces, the scatterers induce very abrupt variations of the phase, polarization and amplitude of the impinging wave, within a very thin membrane. These unconventional electromagnetic properties can lead to major breakthroughs in sensing, imaging and miniaturization.

In particular, optical metasurfaces allow all possible forms of light manipulation with unconventional, extremely thin optical devices, like: flat lenses, deflectors, polarizers, holograms, perfect absorbers, filters, beam shapers, near-to-far-field transducers. Their extraordinary electromagnetic properties and their extremely thin dimensions allow very high levels of integration with other components and sensors.

My main research goal in this field is to enable the development of novel system/instrument concepts based on metasurfaces/metamaterials. To accomplish this goal, we develop modelling/design frameworks, we build and test demonstrators and we embed these structures in the design of complex systems. TNO has a long and world recognized competence in the development of instruments/systems for space, defence and semiconductor industry. With the use of metasurfaces and metamaterials we are enabling the development of a new generation of instruments.

In this context, my research closely contributes to the TNO roadmaps ‘Semiconductor’, ‘Space’ and ‘Information & Sensor systems’.

Recent results

Spectro-polarimetric surfaces for the reconstruction of the polarization states of light in multiple spectral bands have been designed and assessed in terms of performances and manufacturing complexity. One concept has been manufactured and validated experimentally. These surfaces, integrated with a pixelated sensor, could be used for the realization of innovative spectro-polarimetric space instruments (e.g. for aerosol concentration measurements in Earth Observation).
Dielectric metasurfaces have been designed for Surface Enhanced Raman Spectroscopy. The advantages of using dielectric structures, compared to plasmonic ones have been discussed, demonstrating the possibility to achieve same values of enhancement factor, without the disadvantage of ohmic losses inherent of metallic structures. These losses reduce the system efficiency and generate also heat that can modify or damage the analyte under analysis. Furthermore a model has been developed to quantify the effect of optical trapping achieved in the structure in terms an additional increase of the enhancement factor.
An array of nano antennas located in proximity of a scattering source can act as near-to-far-field transducer achieving deep sub-wavelength accuracy in the detection of the scattering source position. Experimental measurements have validated the theoretical results. Such concept can find provide a powerful system in semiconductor metrology.

PhD supervision

Stoevelaar (TNO ERP 3D Nanomanufacturing)
Buijs (NWO HTSM)
Huang (TU/e, CSC scholarship)
P. Gao (China Scholarship Council grant)

Top publications

[1] F. Silvestri, G. Gerini, S. M.B. Bäumer, and E. J. van Zwet , “Robust design procedure for dielectric resonator metasurface lens array”, Optics Express, Vol. 24, Issue 25, Pages: 29153-29169, 2016.
A. Nagarajan, K. Vivek, M. Shah, V. Gopal Achanta, G. Gerini, “A Broadband Plasmonic Metasurface Superabsorber at Optical Frequencies: Analytical Design Framework and Demonstration”, Advanced Optical Materials, 1800253, 2018.
J.Cernigoj, F. Silvestri, L.P. Stoevelaar, J. Berzins, G. Gerini, “Lattice Resonances and Local Field Enhancement in Array of Dielectric Dimers for Surface Enhanced Raman Spectroscopy”, Nature Scientific Reports 8, Article number: 15706, October 2018.
A. Nagarajan, L. P. Stoevelaar, F. Silvestri, M. Siemons, V. Gopal Achanta, S.M. B. Bäumer, G. Gerini, “Reflection confocal nanoscopy using a super-oscillatory lens”, Optics Express, Vol. 27, Issue 14, pp. 20012-20027, 2019.