EventDetails

Speaker:
Luca Leuzzi, PhD

Ultrafast Random lasers are di-verse compounds in which multiple scatter-ing provides the feedback mechanism for light amplification under stimulated emission.
A large collection of random lasers have been investigated in the recent literature, varying in the microscopic structure, in the mechanisms establishing standing modes, and in the optical properties. In particular, the spectral behaviour of optically active ran-dom media above the laser pumping thresh-old turns out to be either deterministic or glassy.
By deterministic optical randomness we mean that a given random molecular struc-ture yields equal random optical spectra in different experiments.
Whereas, glassy randomness appears when a given piece of random medium yields sub-stantially different spectral patterns under different pumping shots.
We quantitatively characterize what 'different' and 'equal' stay for, in terms of shot-to-shot spectral fluctuations. Inspired by spin-glass replica theory, a method is introduced to dis-criminate deterministic and glassy random-ness by means of breaking of the so-called replica symmetry in the overlap between in-tensity fluctuations in different shots.