Abstract
A new device for polarization control at the free electron laser facility FLASH1 at DESY has been commissioned for user operation. The polarizer is based on phase retardation upon reflection off metallic mirrors. Its performance is characterized in three independent measurements and confirms the theoretical predictions of efficient and broadband generation of circularly polarized radiation in the extreme ultraviolet spectral range from 35 eV to 90 eV. The degree of circular polarization reaches up to 90% while maintaining high total transmission values exceeding 30%. The simple design of the device allows straightforward alignment for user operation and rapid switching between left and right circularly polarized radiation.
Highlights
Polarized radiation in the extreme ultraviolet (XUV) spectral range is a powerful tool for element specific investigations of chirality-sensitive light-matter interaction, for example, in molecules with handedness1 or in magnetic materials
Magnetic circular dichroism spectroscopy is a unique technique for transient absorption and reflection spectroscopy,2 time resolved magnetic small-angle scattering,3 and coherent imaging experiments4 combining element selective magnetic sensitivity with nanometer spatial resolution
Before installation and commissioning at FLASH1, the performance of the four-mirror polarizer was characterized at the UE112 PGM-1 beamline of the BESSY II (HZB) synchrotron radiation facility
Summary
Polarized radiation in the extreme ultraviolet (XUV) spectral range is a powerful tool for element specific investigations of chirality-sensitive light-matter interaction, for example, in molecules with handedness or in magnetic materials. With the increasing availability and performance of laser driven high harmonic sources operating in the XUV spectral range, reflection-based polarizers have been rediscovered and applied for ultrafast multi-color magnetic absorption spectroscopy.. With the increasing availability and performance of laser driven high harmonic sources operating in the XUV spectral range, reflection-based polarizers have been rediscovered and applied for ultrafast multi-color magnetic absorption spectroscopy.2 In this context, it is worthwhile to mention that circularly polarized XUV radiation can be generated directly via bi-circular driving fields in high harmonic generation. It is worthwhile to mention that circularly polarized XUV radiation can be generated directly via bi-circular driving fields in high harmonic generation While this was already theoretically predicted and experimentally demonstrated more than 20 years ago, the maturity of laser and high harmonic technology has led to a renaissance of this technique with several very promising experimental implementations in the last few years.. While this was already theoretically predicted and experimentally demonstrated more than 20 years ago, the maturity of laser and high harmonic technology has led to a renaissance of this technique with several very promising experimental implementations in the last few years. it was recently demonstrated that the polarization from an initially unpolarized lab based XUV plasma source can be efficiently controlled with a reflection based apparatus and used for magnetic circular dichroism measurements. elliptically polarized light may be generated by transmission through magnetic foils due to resonant magnetic circular dichroism, inherently limited to the bandwidth of the core hole transition and only with moderate performance
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