Polarization control of an X-ray free electron laser oscillator

TL;DR

This paper proposes a novel tapered crossed-polarized undulator setup for X-ray free electron laser oscillators, enabling highly polarized, fully coherent hard X-ray pulses with rapid polarization switching, advancing X-ray source tunability.

Contribution

It introduces a new undulator configuration for XFELOs that achieves arbitrary polarization control and high coherence in hard X-ray emissions.

Findings

Achieves 99.9% polarization degree in simulations.

Demonstrates 20 KHz polarization switching rate.

Potential for cavity tunable XFELO applications.

Abstract

High-intensity, fully coherent X-ray radiation with a tunable polarization over a wide spectral range is of great importance to many experiments. In this paper, we propose a tapered crossed-polarized undulator configuration for X-ray free electron laser oscillator (XFELO) to produce arbitrarily polarized X-ray pulses in hard X-ray region. A numerical example utilizing the parameters of the Shanghai High-Repetition-Rate XFEL and Extreme Light Facility (SHINE) is presented to demonstrate the generation of polarization controllable, fully coherent Hard X-ray pulses with 99.9% polarization degree and 20 KHz polarization switching rate. This scheme also holds the possibility to be used in cavity tunable XFELO.