Some fundamental considerations on the dynamics of class B laser threshold crossing

TL;DR

This paper uses a simple rate equation model to analyze the intrinsic dynamics of threshold crossing in Class B lasers, providing approximate solutions, numerical verification, and discussing implications for this common laser class.

Contribution

It offers a detailed analysis of threshold dynamics in Class B lasers using a simple model, including approximate solutions and validation methods.

Findings

Approximate solutions for population inversion and field intensity are derived.

Numerical verifications confirm the accuracy of the solutions.

Implications for threshold dynamics in Class B lasers are discussed.

Abstract

With the help of a simple rate equation model, we analyze the intrinsic dynamics of threshold crossing for Class B lasers. A thorough discussion of the characteristics and the limitations of this very commonly employed model, which provides excellent qualitative predictions on the laser behaviour, is offered. Approximate solutions for the population inversion and for the field intensity, up to the point where the latter reaches macroscopic levels, are found and discussed, together with the associated characteristic times. Numerical verifications test the accuracy of these solutions and confirm their validity. A discussion of the implications on threshold dynamics is presented, together with the motivation for focussing on this -- nowadays most common -- class of lasers.