Photonics & Optoelectronics

Contact Persons: Daniele Sanvitto

Keywords: Condensates, Polaritons, Non-Linear Optics
One of the main areas of investigation on the frontiers of physics is the interaction and coupling of light and matter, both from a macroscopic point of view, and on the single particle level. Coherent and collective phenomena such as Bose-Einstein condensation are studied in semiconductor materials and devices, exploiting polaritons: quasi-particles generated by the strong coupling between photons and excited states of matter. Polaritons exhibit very strong nonlinearities, allowing the observation of superfluid dynamics, among the most striking manifestations of macroscopic quantum physics. In particular, we are interested in the dynamics of quantized vortices, optically guided non-equilibrium condensates and the expansion or entrapment of quantum gases. Other fields of interest are the correlation of quantum states and the development of polariton systems based on new materials. In general, inorganic semiconductors and organic or hybrid materials are studied from a fundamental point of view as well as for new application concepts, such as optical transistors, photonic logic gates, machine learning and reservoir computing, up to the most futuristic lines of quantum information processing.

The research lines of the Photonics & Optoelectronics area are listed below:

  1. Attosecond Optoelectronics
  2. Organic Random Lasers
  3. Plasmonics
  4. Polaritons and Quantum Fluid Dynamics
  5. Quantum Polaritons
  6. Photonics Nanostructure Engineering

Attosecond Optoelectronics
Contact Persons: Nicholas Karpowicz, Giovanni Lerario

Keywords: Nonlinear Optics, Optoelectronics, Microscopy, Plasmonics

People: Nicholas Karpowicz, Giovanni Lerario

The waveform of light contains the history of its interaction with matter. With the advent of attosecond science, time-domain access to the sub-cycle structure of visible electromagnetic fields became possible. As a result, it is now known that subtle changes in the waveform of a light pulse can contain a detailed account of the exchange of energy between it and a system of interest, but this presents the significant challenge of obtaining temporal resolution on the order of 1 femtosecond or below. One method of acquiring this resolution is the creation of attosecond pulses of extreme ultraviolet radiation through the high harmonic generation process in gases. An alternative approach, with significant advantages in terms of both flexibility of integration with various experimental systems and overall simplicity is to use optoelectronic methods such as electro-optic sampling. A surprising result of this speeding up of all-optical approaches to electromagnetic field measurement is that it can be extended to spatiotemporal imaging and microscopy with sub-wavelength resolution. Nonlinear plasmonic devices designed to further enhance the sensitivity and spatial resolution of optoelectronic field measurements will allow access to the exact temporal evolution of fields within nanostructures with resolution below the diffraction limit, without raster scanning. Fourier transformation of these fields provides hyperspectral images with complete spectral phase information at each pixel, with a number of applications in physics and biology.

Figure: Near infrared waveform microscopy allows for hyperspectral microscopy with subwavelength resolution (a) while providing the full electric field waveform at each pixel of the image for studies of dynamics with attosecond temporal resolution (b).

Organic Random Lasers
Contact Persons: Ilenia Viola, Valentina Arima

Keywords: Lithographed Devices, Microfluidics, Non-linear Optics, Random Lasers, Supramolecular Organization

People: Valentina Arima, Monica Bianco, Angela Capocefalo, Eleonora Quintiero, Ilenia Viola, Alessandra Zizzari

Random laser emission from scattering nano-aggregates within micrometer smart devices was exploited for the creation of flexible innovative anti-counterfeiting labels for high quality goods and products and / or sensitive documents (ELITE- Progetti di Gruppi di Ricerca – Conoscenza e Cooperazione per un nuovo modello di sviluppo"- Lazio Innova, Regione Lazio – collaboration with N. Ghofraniha, CNR-ISC, Rome).
The smart labels made directly on paper, fabric or polymer, with a total size of a few centimeters, are characterized inside by a nanometric chip, invisible and non-counterfeit, capable of emitting a laser signal uniquely associated with the structure of the device, exclusive digital fingerprint of the valuable good associated.

Figure: a) Photographs of smart lasing labels, printed directly on several substrates, such as paper or polymeric layers. b-d) Confocal z-stack images of different devices realized. The lasing properties of supramolecular assemblies of suitable emitting molecules within smart labels have been investigated.

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Plasmonics
Contact Persons: Milena De Giorgi, Francesco Todisco

Keywords: Polaritons, Plasmons, Plexictons, Plasmon Polariton Condensate

People: Milena De Giorgi, Fabrizio Riminucci, Francesco Todisco

Plasmons are electromagnetic modes associated with the coherent excitation by photons of the free electrons at the interface between a metal and a dielectric material. Their extremely high sensitivity to the geometry of the metallic nanostructures allows an extensive tuning of both the spectral properties and the associated electromagnetic field distribution. Although plasmons have shown unique optical properties, such as extreme light concentration in the near-field, high sensitivity to the surrounding environment and sub-wavelength mode volume, their extremely weak nonlinearities put an important limitation to their integration as active components in nano-optical circuits. This limitation can be overcome by combining metallic nanoparticles with organic or inorganic active materials, exploiting both the sub-wavelength plasmonic mode volume and the high excitonic nonlinearities. The precise control of such hybrid systems, can open the way for a new generation of ultrafast and ultrasmall optical devices. For this reason, our group study the interactions between localized plasmons and nanoscale active components in the strong coupling regime, which leads to the formation of quasiparticles known as plasmon-exciton-polaritons, also called plexcitons. With respect to other polariton systems, the very small effective mode volume of localized plasmon is expected to push the coupling strength towards the THz regime with the added possibility of room temperature operation. The strong-coupling regime is investigated on different platforms, involving different metallic and active materials, type of nanostructures, e.g. nanoparticles of different shapes and sizes, and structures spanning from 1D gratings to 2D arrays of nanostructures and waveguides. The different experimental techniques used for this study range from dark field to bright field optical spectroscopy, up to near-field techniques for the detection of the electromagnetic field at the surface and with spatial resolution below the diffraction limit.

Figure: Metallic bowtie structures trap light in deep sub-diffraction volumes, enabling extremely localized quantum effects. SEM image of a gold plasmonic nanostructure.

Polaritons and Quantum Fluid Dynamics
Contact Persons: Dario Ballarini and Lorenzo Dominici

Keywords: Polariton Fluids and Condensates, Nonlinear Effects, Quantum Vortices, Topology, Hybrid and Organics

People: Dario Ballarini, Luisa De Marco, Lorenzo Dominici, Antonio Gianfrate, Riccardo Panico, Laura Polimeno

Recently, exciton-polaritons in microcavities have attracted particular interest due to their ability to make a phase transition to a state of collective coherence, similar to the Bose-Einstein condensation demonstrated in ultra-cold atoms. In the past years we have observed an incredibly rich phenomenology of quantum effects in fluids of polariton condensates, spanning superfluid flow and persistent currents to the observation of a complex and important dynamics of vortex formation, stability and movement. More recently, thanks to the high degree of control and manipulation that can be exerted upon polariton states, we demonstrated that polaritons can be used as the perfect test-bed for the study of quantum phenomena which are difficult to observe in other systems. Polaritonic structures based on inorganic semiconductors are characterized by high quality factors and nonlinearities, however they work at cryogenic temperatures. These structures are particularly suited to control the formation of quantized vortices and their motion, which is of fundamental importance for the understanding of quantum turbulence and phase transitions, but also for the possibility to implement localized packets, sub-picosecond clocks, pulse structuring, and all-optical logic gates and elaborations based on these phenomena. Alongside these structures there is a whole line of research based on the study of polaritonic systems based on new organic and hybrid materials, which support excitons with high binding energies and strong nonlinearities, making them excellent candidates for future implementations of all-optical or electro-optical devices operating at room temperature. These include polaritonic lasers, fast switches and polaritonic logic circuits, and active Bloch surface waves and waveguides for both sensors and signal manipulation.

Figure: Polariton flow at room temperature hitting an artificial defect in the supersonic and superfluid regimes (top and bottom image, respectively). SEM image of polariton waveguides.

Quantum Polaritons
Contact Persons: Vincenzo Ardizzone, Daniele Sanvitto

Keywords: Single Particle, Quantum Optics, Quantum Information

People: Vincenzo Ardizzone, Milena De Giorgi, Eugenio Maggiolini, Daniele Sanvitto, Daniel Suarez

In an era in which quantum computers promise to offer a new computing paradigm, with a potential increase in the speed of solving many computational problems, significant research is focused on the implementation of quantum algorithms that raise the standard of security in telecommunications, creating new, virtually inviolable, encryption protocols. Today there are still some fundamental difficulties that must be overcome before quantum computers can find real applications. In particular, the encoding, transmission and manipulation of information in quantum form requires the development and use of new technologies based on physical systems with appropriate properties. The main objective of this line of research is to study a new generation of polaritonic devices able to process signals in a way similar to the current generation of processors but without the high dissipation and decoherence of purely electronic components. In particular, we are focusing on the realization of single particle logic gates by using different polaritonic platforms that allow the manipulation and control of polariton fluids through fundamental nonlinear interactions. These systems will be based both on semiconductor microcavities, operating at low temperature (T = 4K), and on materials with very strong nonlinearities and operating at room temperature, with the appropriate nanophotonics structure able to guide the single coupled photons and to enhance the interactions among particles.

Figure: Single polariton inside a planar microcavity structure (left), and concurrence of the photon - polariton entanglement (right).

Photonics Nanostructure Engineering
Contact Persons: Vittorianna Tasco

Keywords: Chiral Metamaterials, Surface Lattice Plasmonic Resonance, Nanofabrication

People: Marco Esposito, Adriana Passaseo, Vittorianna Tasco, Massimo Cuscunà, Iolena Tarantini, Mariachiara Manoccio

Our activities aim at designing and realizing structured nanoscale materials with novel optical properties.
Our study focuses on:

  1. materials: noble and not-noble metals, dielectrics and semiconductors;
  2. new architectures of single, clustered and periodically assembled nanostructures;
  3. different dimensionality like 3D chiral objects.

To get engineered light-matter interactions we develop novel nanofabrication solutions, combining top-down and bottom-up approaches, such as electron beam lithography, focused ion/electron beam nanopatterning and material deposition through atomic layer deposition or chemical vapor deposition techniques.

Figures:

  1. Intertwined nanohelices realized by focused ion beam induced deposition capable to rotate the transmitted light linear polarization axis.
  2. Filtered far field map from aluminum plasmonic oligomers organized in periodic arrays.
  3. Extrinsic chirality in diffractive metasurfaces.
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