A5045102280- Photonic Crystals and Applications
- Photonic and Optical Devices
- Plasmonic and Surface Plasmon Research
- Silicon Nanostructures and Photoluminescence
- Optical Coatings and Gratings
- Strong Light-Matter Interactions
- Quantum and electron transport phenomena
- Semiconductor Quantum Structures and Devices
- Thin-Film Transistor Technologies
- Silicon and Solar Cell Technologies
- Thermal Radiation and Cooling Technologies
- Quantum Dots Synthesis And Properties
- Physics of Superconductivity and Magnetism
- Rare-earth and actinide compounds
- Mechanical and Optical Resonators
- solar cell performance optimization
- Metamaterials and Metasurfaces Applications
- Gold and Silver Nanoparticles Synthesis and Applications
- Nanowire Synthesis and Applications
- Semiconductor Lasers and Optical Devices
- Photorefractive and Nonlinear Optics
- Chalcogenide Semiconductor Thin Films
- Quantum Information and Cryptography
- Advanced Chemical Physics Studies
- Spectroscopy and Quantum Chemical Studies
University of Pavia
2016-2025
Center for Biomolecular Nanotechnologies
2021
Istituto di Fotonica e Nanotecnologie
2018-2019
National Interuniversity Consortium for the Physical Sciences of Matter
2009-2018
Institute for Microelectronics and Microsystems
2013
Istituto Nazionale di Fisica Nucleare, Sezione di Pavia
2003-2012
Polytechnic University of Turin
2008
Karlsruhe Institute of Technology
2008
Magna Graecia University
2008
Centre National de la Recherche Scientifique
2007
We demonstrate that very few (2--4) quantum dots as a gain medium are sufficient to realize photonic-crystal laser based on high-quality nanocavity. Photon correlation measurements show transition from thermal coherent light state proving lasing action occurs at ultralow thresholds. Observation of is unexpected since the cavity mode in general not resonant with discrete dot states and emission those frequencies suppressed. In this situation, quasicontinuous become crucial they provide an...
A study of quantum box transitions coupled to three-dimensionally confined photonic modes in pillar microcavities is presented, focusing on the conditions for achieving a vacuum-field Rabi splitting. For single InAs oscillator strength factor ten too small being strong coupling. calculation exciton states localized monolayer fluctuations wells leads much larger values strengths. Single excitons embedded state-of-the-art micropillars can be strong-coupling regime with
Photovoltaic (PV) conversion of solar energy starts to give an appreciable contribution power generation in many countries, with more than 90% the global PV market relying on cells based crystalline silicon (c-Si). The current efficiency record c-Si is 26.7%, against intrinsic limit ~29%. Current research and production trends aim at increasing efficiency, reducing cost, industrial modules. In this paper, we review main concepts theoretical approaches that allow calculating limits as a...
Binding energies of excitons in quantum wells are calculated including valence-band mixing and also other important effects, namely Coulomb coupling between belonging to different subbands (which is predominantly with the exciton continuum), nonparabolicity bulk conduction band, difference dielectric constants well barrier materials. All these effects found be a comparable size, tend increase binding energies, taken together result very high particularly narrow GaAs/AlAs wells. can even...
A novel electro-optic silicon-based modulator with a bandwidth of 78GHz, drive voltage amplitude 1V and length only 80 microm is proposed. Such record data allow 100Gbit/s transmission can be achieved by exploiting combination several physical effects. First, we rely on the fast strong nonlinearities polymers infiltrated into silicon, rather than slower free-carrier effect in silicon. Second, use Mach-Zehnder interferometer slotted slow-light waveguides for minimizing length, but nonetheless...
The authors show that light scattering from high-Q planar photonic crystal nanocavities can display Fano-like resonances corresponding to the excitation of localized cavity modes. By changing conditions, we are able tune observed lineshapes strongly asymmetric and dispersivelike symmetric Lorentzians. Results interpreted according Fano model quantum interference between two coupled channels. Combined measurements line shape analysis on a series silicon L3 as function nearby hole displacement...
Gradient-based inverse design in photonics has already achieved remarkable results designing small-footprint, high-performance optical devices. The adjoint variable method, which allows for the efficient computation of gradients, played a major role this success. However, gradient-based optimization not yet been applied to mode-expansion methods that are most common approaches studying periodic structures such as photonic crystals. This is because, simulations, method cannot be defined...
A comprehensive theoretical and experimental study of linear exciton-light coupling in single coupled semiconductor microcavities is presented: emphasis given to angular dispersion polarization effects the strong-coupling regime. The phase delay dielectric mirrors carries a nontrivial angle dependence. splitting cavity modes increases with internal as ${\mathrm{sin}}^{2}{\ensuremath{\theta}}_{\mathrm{eff}}.$ Comparison results on GaAs-based...
Noble metal nanowaveguides supporting plasmon polariton modes are able to localize the optical fields at nanometer level for high sensitivity biochemical sensing devices. Here we report on design and fabrication of a novel photonic−plasmonic device which demonstrates label-free detection capabilities single inorganic nanoparticles monolayers organic compounds. In any case, determine Raman scattering signal enhancement limits that reach number molecules between 10 250. The can be...
Valence subbands of uniaxially stressed GaAs-${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Al}}_{\mathrm{x}}$As quantum wells are found by solving exactly the multiband effective-mass equation for envelope function; as in particle a box problem, we first solve each bulk material, and then impose boundary conditions on linear combinations solutions. Discrete symmetries Hamiltonian used to decouple spin-degenerate subbands; energy levels obtained zeros an...
We calculate the exchange interaction (EI) of excitons in quantum wells. The EI is found to depend on in-plane wave vector k, and follows two distinct regimes: for kL\ensuremath{\gg}1, where L well width, enhanced over bulk value. For kL\ensuremath{\ll}1, splitting between longitudinal transverse linear vanishes at k=0: thus common expectation that longitudinal-transverse increases with confinement invalid k=0. Moreover, exciton polarized along growth direction split from planes. present...
According to a recent proposal [S. Takayama et al., Appl. Phys. Lett. 87, 061107 (2005)], the triangular lattice of air holes may allow us achieve complete photonic band gap in two-dimensional crystal slabs. In this work we present systematic theoretical study high-index membrane, and comparison with conventional circular holes, by means guided-mode expansion method whose detailed formulation is described here. Photonic mode dispersion below above light line, maps, intrinsic diffraction...
We theoretically investigate the light-trapping properties of one- and two-dimensional periodic patterns etched on front surface c-Si a-Si thin film solar cells with a silver back reflector an anti-reflection coating. For each active material configuration, absorbance A short-circuit current density Jsc are calculated by means rigorous coupled wave analysis (RCWA), for different materials thicknesses in range interest wide geometrical parameters. The results then compared Lambertian limits...
Different types of planar photonic crystal cavities aimed at optimizing the far-field emission pattern are designed and experimentally assessed by resonant scattering measurements. We systematically investigate interplay between achieving highest possible quality (Q) factor maximizing in- out-coupling efficiency into a narrow cone. Cavities operate telecommunications wavelengths, i.e. around approximately 1.55 microm, realized in silicon membranes. A strong modification pattern, therefore...
The influence of pure dephasing on the dynamics coupling between a two-level atom and cavity mode is systematically addressed. We have derived an effective atom-cavity rate that shown to be key parameter in physics problem, allowing generalize known expression for Purcell factor case broad emitters, define strategies optimize performances emitter-based single-photon sources. Moreover, able restore lasing presence detuning, further demonstration decoherence can seen as fundamental resource...
We present a theoretical optimisation of 1D apodized grating couplers in "pure" Silicon-On-Insulator (SOI) architecture, i.e. without any bottom reflector element, by means general mutative method.We perform comprehensive 2D Finite Difference Time Domain study chirped and 220 nm SOI, demonstrate that the global maximum coupling efficiency platform is capped to 65% (-1.9 dB).Moving designs with thicker Si-layers, we identify new record design 340 simulated 89% (-0.5 dB).Going Si layers does...
Hybrid organic-inorganic perovskites have emerged as very promising materials for photonic applications, thanks to the great synthetic versatility that allows tune their optical properties. In two-dimensional (2D) crystalline form, these behave multiple quantum-well heterostructures with stable excitonic resonances up room temperature. this work strong light-matter coupling in 2D perovskite single-crystal flakes is observed, and polarization-dependent exciton-polariton response used disclose...
Exciton-polaritons are mixed light-matter excitations that result from the strong coupling regime between an active excitonic material and photonic resonances. Harnessing these hybrid provides a rich playground to explore fascinating fundamental features, such as out-of-equilibrium Bose-Einstein condensation quantum fluids of light, well novel mechanisms be exploited in optoelectronic devices. Here, we investigate experimentally formation exciton-polaritons arising mixing inorganic-organic...
We theoretically and experimentally investigate a metasurface supporting silicon-slot quasi-bound state in the continuum (qBIC) mode resonating near-infrared spectrum. The is composed of circular slots etched silicon layer on sapphire substrate. symmetry unit cell reduced order to provide access symmetry-protected mode, whose properties are investigated by finite-element full-wave eigenfrequency analysis. measured transmittance spectra verify excitation qBIC with experimental quality factors...
Manipulating the optical landscape of single quantum dots (QDs) is essential to increase emitted photon output, enhancing their performance as chemical sensors and single-photon sources. Micro-optical structures are typically used for this task, with drawback a large size compared embedded emitters. Nanophotonic architectures hold promise modify dramatically emission properties QDs, boosting light–matter interactions at nanoscale, in ultracompact devices. Here, we investigate interplay...
We prove that reflectivity measurements as a function of angle incidence allow the measurement exciton-polariton modes in quantum wells. The resonant polaritons at ${\mathit{k}}_{\mathrm{?}}$${\mathit{k}}_{0}$=\ensuremath{\omega}/v manifest themselves peaks while surface ${\mathit{k}}_{\mathrm{?}}$>${\mathit{k}}_{0}$ dips attenuated total reflection. A comparison reflectivities with polarization perpendicular and parallel to plane allows us detect different polariton measure dispersion...
The effect of inhomogeneous broadening on exciton-light coupling in quantum wells (QW's) is studied by a semiclassical model, which the exciton resonance frequency assumed to have Gaussian distribution. presence disorder may be observed absorption, but not reflectivity spectra. integrated absorption light single and multiple QW's nonzero only finite damping increases with enhancement either homogeneous or broadening: when larger than radiative width does attain saturation value expected from...