Umberto Celano
Visiting Scholar
IMEC (Leuven, Belgium)
Recent news
Publications
Yifei Wang; Patrick Landreman; David Schoen; Kye Okabe; Ann Marshall; Umberto Celano; H.-S. Philip Wong; Junghyun Park; Mark L. Brongersma
Electrical tuning of phase-change antennas and metasurfaces Journal Article
In: Nature Nanotechnology, vol. 16, pp. 667–672, 2021.
@article{wang2021electrical,
title = {Electrical tuning of phase-change antennas and metasurfaces},
author = {Yifei Wang and Patrick Landreman and David Schoen and Kye Okabe and Ann Marshall and Umberto Celano and H.-S. Philip Wong and Junghyun Park and Mark L. Brongersma},
doi = {10.1038/s41565-021-00882-8},
year = {2021},
date = {2021-04-19},
journal = {Nature Nanotechnology},
volume = {16},
pages = {667\textendash672},
abstract = {The success of semiconductor electronics is built on the creation of compact, low-power switching elements that offer routing, logic and memory functions. The availability of nanoscale optical switches could have a similarly transformative impact on the development of dynamic and programmable metasurfaces, optical neural networks and quantum information processing. Phase-change materials are uniquely suited to enable their creation as they offer high-speed electrical switching between amorphous and crystalline states with notably different optical properties. Their high refractive index has already been harnessed to fashion them into compact optical antennas. Here, we take the next important step, by showing electrically-switchable phase-change antennas and metasurfaces that offer strong, reversible, non-volatile, multi-phase switching and spectral tuning of light scattering in the visible and near-infrared spectral ranges. Their successful implementation relies on a careful joint thermal and optical optimization of the antenna elements that comprise a silver strip that simultaneously serves as a plasmonic resonator and a miniature heating stage. Our metasurface affords electrical modulation of the reflectance by more than fourfold at 755 nm.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The success of semiconductor electronics is built on the creation of compact, low-power switching elements that offer routing, logic and memory functions. The availability of nanoscale optical switches could have a similarly transformative impact on the development of dynamic and programmable metasurfaces, optical neural networks and quantum information processing. Phase-change materials are uniquely suited to enable their creation as they offer high-speed electrical switching between amorphous and crystalline states with notably different optical properties. Their high refractive index has already been harnessed to fashion them into compact optical antennas. Here, we take the next important step, by showing electrically-switchable phase-change antennas and metasurfaces that offer strong, reversible, non-volatile, multi-phase switching and spectral tuning of light scattering in the visible and near-infrared spectral ranges. Their successful implementation relies on a careful joint thermal and optical optimization of the antenna elements that comprise a silver strip that simultaneously serves as a plasmonic resonator and a miniature heating stage. Our metasurface affords electrical modulation of the reflectance by more than fourfold at 755 nm.
Jorik van de Groep; Jung-Hwan Song; Umberto Celano; Qitong Li; Pieter G. Kik; Mark L. Brongersma
Exciton resonance tuning of an atomically thin lens Journal Article
In: Nature Photonics, vol. 14, pp. 426-430, 2020.
@article{van2020exciton,
title = {Exciton resonance tuning of an atomically thin lens},
author = {Jorik van de Groep and Jung-Hwan Song and Umberto Celano and Qitong Li and Pieter G. Kik and Mark L. Brongersma },
doi = {10.1038/s41566-020-0624-y},
year = {2020},
date = {2020-04-27},
journal = {Nature Photonics},
volume = {14},
pages = {426-430},
abstract = {The highly engineerable scattering properties of resonant optical antennas underpin the operation of metasurface-based flat optics. Thus far, the choice of antenna has been limited to shaped metallic and high-index semiconductor nanostructures that support geometrical plasmonic or Mie resonances. Whereas these resonant elements offer strong light\textendashmatter interaction and excellent control over the scattering phase and amplitude, their electrical tunability has proven to be quite limited. Here, we demonstrate how excitonic resonances in atomically thin semiconductors can be harnessed as a different, third type of resonance to create mutable, flat optics. These strong materials-based resonances are unmatched in their tunability with various external stimuli. To illustrate the concept, we first demonstrate how excitons can enhance the focusing efficiency of a millimetre-scale, patterned WS2 zone plate lens. We also show how electrical gating can completely turn on and off the exciton resonance and thereby modulate the focusing efficiency by 33%.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The highly engineerable scattering properties of resonant optical antennas underpin the operation of metasurface-based flat optics. Thus far, the choice of antenna has been limited to shaped metallic and high-index semiconductor nanostructures that support geometrical plasmonic or Mie resonances. Whereas these resonant elements offer strong light–matter interaction and excellent control over the scattering phase and amplitude, their electrical tunability has proven to be quite limited. Here, we demonstrate how excitonic resonances in atomically thin semiconductors can be harnessed as a different, third type of resonance to create mutable, flat optics. These strong materials-based resonances are unmatched in their tunability with various external stimuli. To illustrate the concept, we first demonstrate how excitons can enhance the focusing efficiency of a millimetre-scale, patterned WS2 zone plate lens. We also show how electrical gating can completely turn on and off the exciton resonance and thereby modulate the focusing efficiency by 33%.
