Abstract
X-ray free electron lasers provide short, polarized, high-power pulses of x-ray radiation, where polarization properties are determined by the undulator magnetic field. We propose a cost-effective method to shape the polarization of FEL radiation on the sample both spatially, on a few-$\ensuremath{\mu}\mathrm{m}$ scale, and/or temporally on the 100-femtosecond scale. The method is based on coaxial superposition of two coherent radiation pulses with different frequencies emitted in two consequent undulators set to emit radiation with orthogonal polarization states. Its capabilities are demonstrated via numerical simulations for the SASE3 undulator line of the European X-ray Free-Electron Laser. Generation of x-ray free-electron laser pulses with shaped polarization may be interesting for studies of magnetism or ultrafast phenomena and will facilitate further developments of complex light engineering in the soft X-ray range.
Highlights
Free electron lasers (FELs) opened up the possibility of obtaining polarized x-ray pulses with unprecedented power and femtosecond-order duration [1].Generation of structured light and, in particular, radiation with structured polarization, has interesting prospects for the future, as outlined in [2] and references therein
The method is based on coaxial superposition of two coherent radiation pulses with different frequencies emitted in two consequent undulators set to emit radiation with orthogonal polarization states
In this paper we propose a simple method to shape the polarization state of the FEL radiation using only components already developed for such facilities, namely helical undulators, phase-shifters, longitudinal wakefield structures [7], and reflective x-ray mirrors
Summary
Free electron lasers (FELs) opened up the possibility of obtaining polarized x-ray pulses with unprecedented power and femtosecond-order duration [1]. Its location along the circle is determined by the phase difference Δφ between the beams This scheme was first proposed in [10] as a way of generating circularly polarized radiation at synchrotron facilities, as illustrated on Fig. 2(a). Later this approach was extended for FELs and circular polarization basis [11], as illustrated on Fig. 2(b), experimentally demonstrated for crossed planar and helical undulators [12,13,14,15] In order for this method to work, it is important that the phase difference Δφ between the two polarized pulses is kept fixed both transversely and in time. No synchronism takes place and on average the “seed” does not interact with the electron beam (see Appendix A)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
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 call
