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An optics-free method is proposed to generate x-ray radiation with spatially variant states of polarization via an afterburner extension to a free electron laser. Control of the polarization in the transverse plane is obtained through the overlap of different coherent transverse light distributions radiated from a bunched electron beam in two consecutive orthogonally polarised undulators. Different transverse profiles are obtained by emitting at a higher harmonic in one or both of the undulators. This method enables the generation of beams structured in their intensity, phase, and polarization—so-called Poincaré beams—at high powers with tunable wavelengths. Simulations are used to demonstrate the generation of two different classes of light with spatially inhomogeneous polarization—cylindrical vector beams and full Poincaré beams. [ABSTRACT FROM AUTHOR]

With intensities 108-1010 times greater than other laboratory sources, X-ray free-electron lasers are currently opening up new frontiers across many areas of science. In this Review we describe how these unconventional lasers work, discuss the range of new sources being developed worldwide, and consider how such X-ray sources may develop over the coming years. [ABSTRACT FROM AUTHOR]

The article reports that the scientists of SLAC National Accelerator Laboratory in Menlo Park, California, have successfully completed a free-electron laser (FEL) facility which can achieve lasing at a wavelength of 1.5 Å. Experts believe that this FEL, the first to operate in the hard X-ray regime, will open up vast new areas for scientific exploration in the field of light-source science. They state that this source will help in study of atomic and molecular science.

The article discusses on the free-electron lasers (FELs) operating at X-ray wavelengths to gather detailed information on how matter interacts and arranges itself at atomic and molecular scales. It states that the output from the FEL is around 108 brighter than current synchrotron sources. The information gathered by the X-ray FELs about molecules, atoms and their electronic states are more efficient than current synchrotron X-ray sources.

In this paper, we propose for first time practical parameters to construct a compact sub-Angstrom Free Electron Laser (FEL) based on Compton backscattering. Our recipe is based on using picocoulomb electron bunch, enabling very low emittance and ultracold electron beam. We assume the FEL is operating in a quantum regime of Self Amplified Spontaneous Emission (SASE). The fundamental quantum feature is a significantly narrower spectrum of the emitted radiation relative to classical SASE. The quantum regime of the SASE FEL is reached when the momentum spread of the electron beam is smaller than the photon recoil momentum. Following the formulae describing SASE FEL operation, realistic designs for quantum FEL experiments are proposed. We discuss the practical constraints that influence the experimental parameters. Numerical simulations of power spectra and intensities are presented and attractive radiation characteristics such as high flux, narrow linewidth, and short pulse structure are demonstrated. [ABSTRACT FROM AUTHOR]