Abstract
We show that the macropulse instability affecting storage ring free-electron laser (FEL) oscillators can be suppressed using a delayed optical feedback. The principle, known as coherent photon seeding, consists in reinjecting a very small part of the laser output in the laser cavity in order to create a new deterministic solution. The feedback is shown to be efficient over a large range of the detuning parameter of the FEL cavity, even with very small fractions of reinjected power ($<{10}^{\ensuremath{-}8}$ here from inside to inside the cavity). The experiments have been performed on the UVSOR-II storage ring free-electron laser.
Highlights
Free-electron lasers (FELs) are coherent light sources based on the interaction between relativistic electron bunches and a spatially periodic magnetic field [1,2]
We focus on a surprising side effect of this all-optical feedback
The storage ring operates with two electron bunches, and the FEL is tuned at 420 nm
Summary
Free-electron lasers (FELs) are coherent light sources based on the interaction between relativistic electron bunches and a spatially periodic magnetic field [1,2]. They emit femtosecond/picosecond laser pulses synchronized with the electron bunches. The FEL dynamics is mainly governed by the synchronism between the optical pulses and the electron bunches either circulating in a storage ring [3,4] or coming from a linear accelerator [5,6,7,8]. In storage ring FEL oscillators (SR-FELs), except near perfect synchronism, where the FEL emits stable picosecond pulses of constant amplitude, dynamical instabilities are systematically observed. The dynamics become hypersensitive to noise, in a way that
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Physical Review Special Topics - Accelerators and Beams
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
