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.


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




CNR Researcher



CNR Researcher



CNR Researcher



Associate PostDoc


  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

La settimana del rosa digitale - 4^ed

La settimana del rosa digitale - 4^ed


Percorso di condivisione della carriera di scienziato-donna fatto attraverso esperimenti di estrazione di sostanze chimiche partendo dal cibo.

11 e 15 marzo 2019

Via Marconi,39 - Casamassima Bari 70010

Che “cavolo" di arcobaleno-mamme e scienza un viaggio alla scoperta di cio’ che Madre Natura ci insegna.

con Eloisa Sardella (CNR Nanotec) e Laura Rosso (PSP)

maggiori info:

TERAMETANANO - International Conference on Terahertz Emission, Metamaterials and Nanophotonics


Castello Carlo V, Lecce 27 -31 Maggio 2019

The IV edition of TERAMETANANO, the International Conference on Terahertz Emission, Metamaterials and Nanophotonics, will take place in Lecce (Italy) from 27 to 31 of May 2019 in the 16th-century Castle of Charles V   with two special nights that will be held in an original Theatre of Roman period.


TERAMETANANO is an annual conference that gather physicists studying a wide variety of phenomena in the areas of nano-structuresnano-photonics and meta-materials, with special attention to the coupling between light and matter and in a broad range of wavelengths, going from the visible up to the terahertz.


Al via la fase 2 del Tecnopolo per la medicina di precisione

Firmata convenzione tra Regione, Università e Cnr per avvio seconda fase del Tecnopolo

Bari, 27 novembre 2018 

Sottoscritto stamane l’accordo tra Regione PugliaCnr Consiglio nazionale delle ricerche, Irccs Giovanni Paolo II di Bari e Università di Bari per l’avvio della seconda fase del Tecnopolo per la Medicina di Precisione. Sede del tecnopolo, il CnrNanotec.

“La sfida della medicina moderna è tradurre nella pratica clinica gli enormi progressi compiuti dalla scienza e dalla tecnologia. In questo contesto le nanotecnologie, focalizzate sull’indagine e sulla manipolazione della materia a livello nanometrico-molecolare, si presentano come uno strumento potentissimo al servizio della medicina di precisione, la nuova frontiera che punta allo sviluppo di trattamenti personalizzati per il singolo paziente”, afferma  Giuseppe Gigli, direttore di Cnr Nanotec e coordinatore del Tecnopolo.

Link video dichiarazione Massimo Inguscio:

Link video di presentazione Tecnomed:

Link video dichiarazione Michele Emiliano: