Modeling of photon density dynamics in random lasers (5 pages)

Óscar G. Calderón, E. Cabrera

Mikhail A. Noginov, J. Novak, S. N. Williams

The dynamics of stimulated emission in random lasers is studied using the system of rate equations for population inversion and density of emitted photons. In order to model the behavior of random lasers with nonresonant feedback, no coherence effects are intentionally taken into account. It has been shown that the feedback in the system is necessary for the realization of the regime of relaxation oscillations and spatial confinement of the stimulated emission to the interior regions of the pumped volume. The model also predicts the possibility of localization of stimulated emission in several spatially separated subvolumes of the random laser medium. Finally, it has been demonstrated that two adjacent random laser volumes can strongly enhance the stimulated emission in each other (the ``critical mass'' effect in random lasers).

C. W. J. Beenakker

P. P. Jauho, D.O. Riska, Stig Stenholm

Jan De Boer A, Jildou Hollander, Andrew Rolph

A bstract We show how to capture both the non-unitary Page curve and replica wormhole-like contributions that restore unitarity in a toy quantum system with random dynamics. The motivation is to find the simplest dynamical model that captures this aspect of gravitational physics. In our model, we evolve with an ensemble of Hamiltonians with GUE statistics within microcanonical windows. The entropy of the averaged state gives the non-unitary curve, the averaged entropy gives the unitary curve, and the difference comes from matrix index contractions in the Haar averaging that connect the density matrices in a replica wormhole-like manner.

A. Lukš, Vlasta Perinov

The model of a random laser is reconsidered which utilises Langevin equations as appropriate for calculations of photon statistics. A "probabilistic description" is outlined, i.e., equations governing the temporal evolution of the probabilities of photon numbers in the radiation modes and the densities of the excited atoms in the medium. The usual procedure of numerical solution is extended by monitoring numbers of the photons absorbed by a photodetector.