  L\'evy flights for light have been demonstrated in disordered systems with
and without optical gain, and remained unobserved in ordered ones. In the
present letter, we investigate, numerically and experimentally, L\'evy flights
for light in ordered systems due to an ordered (conventional) laser. The
statistical analysis was performed on the intensity fluctuations of the output
spectra upon repeated identical experimental realizations. We found out that
the optical gain and the mirrors reflectivity are critical parameters governing
the fluctuation statistics. We identified L\'evy regimes for gain around the
laser threshold, and Gaussian-L\'evy-Gaussian crossovers were unveiling when
increasing the gain from below to above the threshold. The experimental results
were corroborated by Monte Carlo simulations, and the fluctuations were
associated to a Langevin noise source that takes into account the randomness of
the spontaneous emission, which seeds the laser emission and can cause large
fluctuations of the output spectra from shot-to-shot under identical
experimental realizations.

Optics