Searched for: author:"Alpeggiani, F."
(1 - 16 of 16)
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Parappurath, Nikhil (author), Alpeggiani, F. (author), Kuipers, L. (author), Verhagen, Ewold (author)
Topological protection in photonics offers new prospects for guiding and manipulating classical and quantum information. The mechanism of spin-orbit coupling promises the emergence of edge states that are helical, exhibiting unidirectional propagation that is topologically protected against back scattering. We directly observe the topological...
journal article 2020
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Gong, S. (author), Komen, I. (author), Alpeggiani, F. (author), Kuipers, L. (author)
Valley pseudospin has emerged as a good quantum number to encode information, analogous to spin in spintronics. Two-dimensional transition metal dichalcogenides (2D TMDCs) recently attracted enormous attention for their easy access to the valley pseudospin through valley-dependent optical transitions. Different ways have been reported to read...
journal article 2020
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Alpeggiani, F. (author), Kuipers, L. (author)
Bichromatic photonic crystal structures are based on the coexistence of two different periodicities in the dielectric constant profile. They are realized starting from a photonic crystal waveguide and modifying the lattice constant only in the waveguide region. In this work, we numerically investigate the spectral and topological properties...
journal article 2019
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de Angelis, L. (author), Bauer, T.A. (author), Alpeggiani, F. (author), Kuipers, L. (author)
When the positions of two generic singularities of equally signed topological index coincide, a higher-order singularity with twice the index is created. In general, singularities tend to repel each other when sharing the same topological index, preventing the creation of such higher-order singularities in 3D generic electromagnetic fields....
journal article 2019
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Alpeggiani, F. (author), Bliokh, K. Y. (author), Nori, F. (author), Kuipers, L. (author)
Optical helicity density is usually discussed for monochromatic electromagnetic fields in free space. It plays an important role in the interaction with chiral molecules or nanoparticles. Here we introduce the optical helicity density in a dispersive isotropic medium. Our definition is consistent with biorthogonal Maxwell electromagnetism in...
journal article 2018
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Picardi, M. F. (author), Bliokh, K. Y. (author), Rodríguez-Fortuño, J. F. (author), Alpeggiani, F. (author), Nori, F. (author)
Spin and orbital angular momenta (AM) of light are well studied for free-space electromagnetic fields, even nonparaxial. One of the important applications of these concepts is the information transfer using AM modes, often via optical fibers and other guiding systems. However, the self-consistent description of the spin and orbital AM of...
journal article 2018
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Gong, S. (author), Alpeggiani, F. (author), Sciacca, Beniamino (author), Garnett, Erik C. (author), Kuipers, L. (author)
The emergence of two-dimensional transition metal dichalcogenide materials has sparked intense activity in valleytronics, as their valley information can be encoded and detected with the spin angular momentum of light. We demonstrate the valley-dependent directional coupling of light using a plasmonic nanowire-tungsten disulfide (WS<sub>2<...
journal article 2018
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Alpeggiani, F. (author), Gong, Su Hyun (author), Kuipers, L. (author)
The two-dimensional excitons of transition metal dichalcogenide (TMDC) monolayers make these materials extremely promising for optical and optoelectronic applications. When the excitons interact with the electromagnetic field, they will give rise to exciton-polaritons, i.e., modes that propagate in the material plane while being confined in...
journal article 2018
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de Angelis, L. (author), Alpeggiani, F. (author), Di Falco, Andrea (author), Kuipers, L. (author)
Phase singularities are locations where light is twisted like a corkscrew, with positive or negative topological charge depending on the twisting direction. Among the multitude of singularities arising in random wave fields, some can be found at the same location, but only when they exhibit opposite topological charge, which results in their...
journal article 2017
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Alpeggiani, F. (author), Parappurath, N. (author), Verhagen, Ewold (author), Kuipers, L. (author)
The scattering matrix is a fundamental tool to quantitatively describe the properties of resonant systems. In particular, it enables the understanding of many photonic devices of current interest, such as photonic metasurfaces and nanostructured optical scatterers. In this contribution, we show that the scattering matrix of a photonic system...
conference paper 2017
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Parappurath, N. (author), Alpeggiani, F. (author), Kuipers, L. (author), Verhagen, Ewold (author)
We observe that the asymmetric transmission (AT) through photonic systems with a resonant chiral response is strongly related to the far-field properties of eigenmodes of the system. This understanding can be used to predict the AT for any resonant system from its complex eigenmodes. We find that the resonant chiral phenomenon of AT is...
journal article 2017
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Simbula, A. (author), Schatzl, M. (author), Alpeggiani, F. (author), Andreani, L.C. (author), Schäffler, F. (author), Fromherz, T. (author), Galli, M. (author), Gerace, D. (author)
We report on the realization of high-Q/V photonic crystal cavities in thin silicon membranes, with resonances around 1.55 μm wavelength. The cavity designs are based on a recently proposed photonic crystal implementation of the Aubry-André-Harper bichromatic potential, defined from the superposition of two one-dimensional lattices with a non...
journal article 2017
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Alpeggiani, F. (author), Parappurath, N. (author), Verhagen, E. (author), Kuipers, L. (author)
It is well known that the quasinormal modes (or resonant states) of photonic structures can be associated with the poles of the scattering matrix of the system in the complex-frequency plane. In this work, the inverse problem, i.e., the reconstruction of the scattering matrix from the knowledge of the quasinormal modes, is addressed. We develop...
journal article 2017
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de Angelis, L. (author), Alpeggiani, F. (author), Di Falco, Andrea (author), Kuipers, L. (author)
Phase singularities can be created and annihilated, but always in pairs. With optical near-field measurements, we track singularities in random waves as a function of wavelength, and discover correlations between creation and annihilation events.
conference paper 2017
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Parappurath, N. (author), Alpeggiani, F. (author), Kuipers, L. (author), Verhagen, E. (author)
We develop a theoretical formalism which explains asymmetric transmission (AT) in chiral resonators from their eigenmodes. We derive a fundamental limit for AT and propose the design of a chiral photonic crystal offering 84% AT.
conference paper 2017
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de Angelis, L. (author), Alpeggiani, F. (author), Di Falco, Andrea (author), Kuipers, L. (author)
Phase singularities arise in scalar random waves, with spatial distribution reminiscent of particles in liquids. Supporting near-field experiment with analytical theory we show how such spatial distribution changes when considering vector waves.
conference paper 2016
Searched for: author:"Alpeggiani, F."
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