Time Dependent Theory for Random Lasers

TLDR

The paper presents a model to simulate random lasing. The model couples Maxwell’s equations with electronic population rate equations in a disordered medium and uses finite‑difference time‑domain methods to compute field patterns and spectra of localized lasing modes. The study finds a critical pumping rate for lasing peaks, shows that the number of modes grows with pump power and system length, and that mode repulsion causes saturation of mode count, linking localization length ξ to average mode length L_m.

Abstract

A model to simulate the phenomenon of random lasing is presented. It couples Maxwell's equations with the rate equations of electronic population in a disordered system. Finite difference time domain methods are used to obtain the field pattern and the spectra of localized lasing modes inside the system. A critical pumping rate P(c)(r) exists for the appearance of the lasing peaks. The number of lasing modes increases with the pumping rate and the length of the system. There is a lasing mode repulsion. This property leads to a saturation of the number of modes for a given size system and a relation between the localization length xi and average mode length L(m).