Organic random lasers

Random Lasers (RLs) are realized in disordered media with gain; the feedback for stimulated emission of light is given by the scattering and no external cavity is needed. The cavity is given by multiple scattering. Therefore, when light rays penetrate these materials they interfere with each other because of scattering and, by different material-dependent mechanisms, they establish standing modes.
In a RL the multiple scattering process defines optical modes with a certain central frequency and bandwidth, lifetime and a rich spatial profile. Recently promising methods for the fabrication of planar lasers are referred to RLs and are based on active molecular layers in which defects, aggregates or external beads behave as scattering centers. To build a RL it is important to create strong enough scattering for the material to become optically thick. However, due to the intrinsically randomness of the scattering centers, conventional methods for the fabrication of RLs do not allow for a careful control of the device geometrical parameters, and in turn of the lasing properties. We describe the use of semiconductor organic materials for RL devices in term of physical-chemical properties, characteristics and advantages. Non-conventional self-organization and lithographic processes have been used for the realization of nanoscale organic random lasers. For the first time, the glassy nature of RL spectral intensity fluctuations  was experimentally demonstrated in a solid disordered system.

Highlights:

We demonstrate the random laser emission RandomLaserfrom scattering nano-aggregates of an organic thiophene-based molecule, obtained in a controlled way by a simple soft lithography technique. The use of surface-tension driven (STD) lithographic processes allows to obtain organic RLs with desired shapes and in which the scattering centers are thiophene aggregates formed by spontaneous molecular self-assembly.

The optimization of the deposition procedure and process kinetics lead to tailor the coherent emission properties by controlling the distribution and the size of the random scatterers.

We reported on the first realization of lasing devices from flexible sheets of common and biodegradable paper, without the presence of any optical cavity and by creating on the cellulose fibres microfluidic porous channels in which a lasing dye can flow by capillarity.Fiber

Such a paper-based RL device attests a geometry induced transition in RLs: from a non-resonant RL where the feedback mechanism is solely given by the scattering effect of paper to a resonant RL where the same material, constrained in micro-channels with defined walls and acting as cavity, shows a laser-like behaviour.

We investigate pulse-to-pulse fluctuations in random lasers, we introduce and measure the intensity fluctuation overlap (IFO), the analogue of the Parisi overlap in independent experimental realizations of the same disordered sample, i.e., the experimental realization of  mathematical replicas.OrganicLaser

We find that the IFO distribution function yields evidence of a transition to a glassy light phase compatible with a replica symmetry breaking. In an amorphous crystal of thiophene-based oligomer, whose optical behavior under external pumping can be properly represented by a spin-glass theory,  we measure the IFO parameter distribution function and we find a behaviour akin to the one theoretically representing the spin-glass phase (at high pumping) and the paramagnetic/fluorescence phase (at low pumping), and we clearly identify the transition between them, i.e., the lasing threshold.

Facilities & Labs

Nanotec @ Lecce

S.Li.M. Lab @ Roma

People

Ilenia_ViolaIenia

Viola

CNR Researcher

leuzziLuca

Leuzzi

CNR Researcher

Valentina_ArimaValentina

Arima

CNR Researcher

Antonella_ZacheoAntonella

Zacheo

Associate PostDoc

Publications

  1. Ghofraniha, I. Viola, F. Di Maria, G. Barbarella, G. Gigli, L. Leuzzi, C. Conti, Experimental evidence of replica symmetry breaking in random lasers, Nat. Comm. 6, 6058 (2015), doi:10.1038/ncomms7058.
  2. Ghofraniha, I. Viola, F. Di Maria, G. Barbarella, G. Gigli, C. Conti,  Random laser from engineered nanostructures obtained by surface tension driven lithography, Laser & Photonics Rev. 7, 432-438, (2013), doi: 10.1002/lpor.201200105.
  3. Viola, N. Ghofraniha, A. Zacheo, V. Arima, C. Conti, G. Gigli, Random laser emission from paper-based device, J. Mater. Chem. C 8, 8128-8133,  (2013), doi: 10.1039/C3TC31860E.
  4. Ghofraniha, I. Viola, A. Zacheo, V. Arima, G. Gigli, C. Conti, Transition from  non-resonant to resonant random lasers by the  geometrical confinement of  disorder, Opt. Lett. 38, 5043-5046 (2013), doi: 10.1364/OL.38.005043.

Latest News

Technology Trasfer in Nanotechnology

Technology Transfer in Nanotechnology: Challenges and Opportunity

Lecce, 18/19 ottobre 2018

CNR NANOTEC c/o Campus Ecotekne

JRC in collaboration with the National Research Council (Cnr) is organising a workshop on Technology Transfer in Nanotechnology,

which will take place in CNR Nanotec (Lecce, Italy) on 18 and 19 October. This workshop is organised in the framework of the TTO-CIRCLE initiatives.   The aim of this event is to explore how technology transfer activities can be used as a mechanism to help EU industry, particularly Start-ups and SMEs, and Government in deploying and adopting Nano-technology. Practical examples will be presented to illustrate the potential of technology transfer in this area.   The workshop will gather technology providers, industry executives, technology transfer officers, policy makers and financial intermediaries to share experiences and lessons learned. One of the key objectives is to discuss policy implications at all levels that could help accelerating the adoption of Nanotechnology by the European manufacturing industry. More informations: https://ec.europa.eu/jrc/communities/community/european-tto-circle/event/technology-transfer-nanotechnology Download Locandina

Nanotechnology Transfer Day

26 Luglio 2018 - Lecce

CNR NANOTEC c/o Campus Ecotekne Siglato l’accordo lo scorso maggio tra CNR NANOTEC e Pairstech Capital Management, ha preso il via la collaborazione con PhD TT per la valutazione della ricerca

E’partita la collaborazione con PhD TT per la valorizzazione della ricerca sulla base dell’accordo siglato lo scorso Maggio tra CNR NANOTEC e Pairstech Capital Management, società di gestione patrimoniale che fornisce agli investitori istituzionali e privati un insieme di veicoli di investimento, al fine di valorizzare i risultati della ricerca svolta all'interno dell'Istituto.

Giovedì 19 Luglio dalle ore 11 alle ore 14 nella sede del CNR Nanotec di Lecce si è tenuto un incontro sul trasferimento tecnologico nel settore delle nanotecnologie applicate al settore biomedicale.

L’evento è stato organizzato dall’ufficio di Trasferimento Tecnologico del CNR Nanotec che ha inaugurato con questa giornata un ciclo di eventi mirato a presentare agli attori dell’ecosistema dell’innovazione nel settore delle nanotecnologie i vari modelli e alcune best practice di trasferimento tecnologico. In questa prima giornata il dott. Heber Verri e la dott.ssa Paola Urbani hanno presentato il nuovo modello di trasferimento tecnologico PhD TTãIndex Model.

PhD TT è una realtà italiana completamente indipendente specializzata in trasferimento tecnologico, è un acceleratore organizzato per il Go to Venture Practice, orientata al mondo delle Lifes Sciences.

PhD TT ha sviluppato un nuovo modello di trasferimento tecnologico: il PhD TT©INDEX MODEL dedicato alla generazione di valore dell'innovazione, focalizzato alla riduzione dei rischi delle opportunità di investimento a sostegno della ricerca.

I ricercatori intervengono attivamente nell'analisi iniziale di fattibilità e nella costituzione della futura società (start-up), con l'obiettivo di attrarre capitale di rischio utile a sostenere la fase del trasferimento tecnologico nella visione della "Research for go-to-market".

Il modello PhD TT nasce da un bisogno del mercato, quello di far dialogare due mondi estremamente diversi tra loro: il mondo della ricerca e il mondo degli investimenti.

PhD TT supporta tutte le attività in collaborazione con il TTO - CNR Nanotec con un team di lavoro esperto e grazie a un comitato scientifico-economico qualificato.

In occasione dell'evento del 19/7 u.s. al CNR Nanotec di Lecce, PHD TT ha presentato il proprio track record, dove si sono potuti valutare in dettaglio i casi di successo di intervento del PhD TT©INDEX MODEL.

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Disordered serendipity: a glassy path to discovery

A workshop in honour of Giorgio Parisi’s 70th birthday

September 19-21, 2018 - Roma

Sapienza University

With the occasion of celebrating Giorgio Parisi 70th birthday, the conference "Disordered serendipity: a glassy path to discovery" brings to Rome many among the world-leading experts in the field of complex systems. In order to properly represent the many fields of research where Giorgio Parisi gave a relevant contribution in his studies of disordered systems, the conference covers a broad spectrum of topics: from  fundamental and rigorous analysis of the statistical mechanics of disorder systems to applications in biology and computer science. These subjects are deeply interconnected since they are characterized by the presence of glassy behavior.

 

https://sites.google.com/site/disorderedserendipity/