Tunable Lasers Handbook

9

Tunable Free-Electron Lasers

Stephen Vincent Benson,     Accelerator Division Continuous Electron Beam Accelerator Facility Newport News, Virginia

1. INTRODUCTION

1.1 Description of FEL Physics

The free-electron laser (FEL) uses a relativistic beam of electrons passing through an undulating magnetic field (a wiggler) to produce stimulated emission of electromagnetic radiation (Fig. 1). The quantum-mechanical description for this device is based on stimulated emission of Bremsstrahlung [1]. The initial and final states of the electron are continuum states so the emission wavelength is not fixed by a transition between bound states. Although the initial description by Madey was quantum mechanical, there was no dependence of the gain on Planck’s ...