Introduction to the Physics of Free Electron Laser and Comparison with Conventional Laser Sources

TL;DR

This paper introduces free electron lasers (FELs), comparing their coherent radiation mechanisms with conventional lasers, highlighting their similarities and differences in operation and underlying physics.

Contribution

It provides a foundational overview of FEL physics, contrasting it with conventional laser mechanisms, and discusses key operational parameters.

Findings

FELs generate coherent radiation via stimulated emission from relativistic electron beams.

FEL operation can be described using parameters similar to conventional lasers.

Despite different mechanisms, FELs can be considered analogous to lasers in many effects.

Abstract

This report is a primer introduction on the sources of coherent syncrotron radiation from FELs compared to conventional lasers. Even though the underlying mechanisms are different, FELs can be considered a laser source to all effects. In fact FEL is based on the stimulated emission of virtual photons by a relativistic electron beam, passing through an undulator/wiggler, much like conventional lasers exploit the stimulated emission by an atomic/molecular system on which a population inversion has been realized. FEL operation is illustrated by means of the usual set of parameters (gain, saturation intensity...) used to describe the functioning of conventional lasers.