This is the website of the Laboratory of Nonlinear Photonics and Theoretical Physics at the Department of Physics of the University Sapienza. Our program is applying paradigms from the science of complex systems to light propagation, and investigating the development of complexity and self-organization in nonlinear waves. We want to test and deepen ideas of fundamental physics by using optics and photonics, and developing experiments, high performance computing approaches, and theory.
OPN Special Issue: Optics in 2013
In the special issue of Optics & Photonics News about Optics in 2013, two contributions of people in our group appeared, also including one proposal for the cover by Marco Leonetti.
Control of random lasers by Marco Leonetti, Claudio Conti, and Cefe Lopez
Shock Waves in Random Media by Silvia Gentilini, Neda Ghofraniha, Eugenio Del Re, and Claudio Conti
Last Updated (Friday, 06 December 2013 07:24)
Anderson localization with a purely nonlinear origin
Anderson localization concerns the transition to a regime in which all the modes of a disordered system are exponentially localized. It also often and generically refers to wave-localizations in a disordered potential.
In general the potential that induces these states is linear; but one may argue if, in a linearly homogeneous medium, localizations may arise from a random modulation of the nonlinear response. This is what Viola Folli, Katia Gallo and Claudio Conti investigate in a paper published in Optics Letters.
It turns out that disorder-induced localized states may have a purely nonlinear origin, but this is accompanied by instability processes that amplify the Anderson states and lead to complicated nonlinear dynamics, still un-explored. An example is given in the process of parametric down-conversion in periodically poled crystals for optical second harmonic generation (picture below).
A notable property of purely nonlinear Anderson states is the fact that their localization length is determined by the input power.
Last Updated (Friday, 06 December 2013 20:44)
Random Laser in Paper!
Dynamics of Phase-Locking in Random Lasers
In a paper published in the Physical Review A, Marco Leonetti, Claudio Conti, and Cefe Lopez report on experimental investigations of the random laser emission from micron-sized clusters of TiO2 particles by using pump pulses with different pulse durations.
It is found that the spectral properties depend on the pulse duration, and this is explained in terms of phase-locking processes in random lasers that is enhanced for nano-second pump pulses and limited in the pico-second (or shorter) regime. This furnishes further evidence of the mode-locking processes in random lasers. The results also supported by numerical solutions of the coupled mode theory equations (CMT).