Diagrammatic semiclassical laser theory

TL;DR

This paper develops a comprehensive semiclassical laser theory using diagrammatic methods, enabling exact treatment of nonlinearity and controlled inclusion of population pulsations, applicable to complex laser systems.

Contribution

It introduces a diagrammatic resummation approach for laser equations, allowing exact nonlinear analysis and inclusion of population pulsations in a unified framework.

Findings

Reproduces all-order nonlinear laser equations under constant inversion.

Incorporates third-order equations with population pulsations.

Applicable to open and irregular laser systems like random lasers.

Abstract

We derive semiclassical laser equations valid in all orders of nonlinearity. With the help of a diagrammatic representation, the perturbation series in powers of electric field can be resummed in terms of a certain class of diagrams. The resummation makes it possible to take into account a weak effect of population pulsations in a controlled way, while treating the nonlinearity exactly. The proposed laser theory reproduces the all-order nonlinear equations in the approximation of constant population inversion and the third-order equations with population-pulsation terms, as special cases. The theory can be applied to arbitrarily open and irregular lasers, such as random lasers.