Experimental demonstration of frequency pulling in single-pass free-electron lasers

E Allaria,G De Ninno,C Spezzani

doi:10.1364/oe.19.010619

Abstract

Frequency pulling is a well-known phenomenon in standard laser physics, leading to a shift of the laser frequency when the cavity and maximum gain frequencies are detuned. In this letter we present the first experimental demonstration of frequency pulling in single-pass free-electron lasers. Measurements are performed using the single-pass free-electron laser installed on the Elettra storage ring.

Highlights

Frequency pulling is a well-known phenomenon in standard laser physics, leading to a shift of the laser frequency when the cavity and maximum gain frequencies are detuned
Frequency pulling is a well-known phenomenon in standard lasers, taking place when the peak of the gain spectrum is slightly detuned with respect to the frequency of one of the modes selected by the laser cavity
In the early days of free-electron lasers (FEL)’s, the study of frequency pulling has been focused on oscillator systems [6]. For such FEL configuration, the effect of frequency pulling is similar to that taking place in standard lasers: the laser frequency is determined by the interplay between the proper frequencies of the cavity and that for which the gain is maximum [7, 8]

Summary

Introduction

Frequency pulling is a well-known phenomenon in standard laser physics, leading to a shift of the laser frequency when the cavity and maximum gain frequencies are detuned. For such FEL configuration, the effect of frequency pulling is similar to that taking place in standard lasers: the laser frequency is determined by the interplay between the proper frequencies of the cavity and that for which the gain is maximum [7, 8]. In a recent work [10], we have theoretically predicted that, in seeded FEL’s, a mismatch between the frequencies “selected” by the seed and the peak of the FEL gain curve may lead to a frequency-pulling effect.

Results

Conclusion