Selective phase filtering of charged beams with laser-driven antiresonant hollow-core fibers

Abstract

Emerging accelerator concepts increasingly rely on the combination of high-frequency electromagnetic radiation with electron beams, enabling longitudinal phase space manipulation which supports a variety of advanced applications. The handshake between electron beams and radiation is conventionally provided by magnetic undulators which unfortunately require a balance between the electron beam energy, undulator parameters, and laser wavelength. Here we propose a scheme using laser-driven large-core antiresonant optical fibers to manipulate electron beams. We explore two general cases using ${\mathrm{TM}}_{01}$ and ${\mathrm{HE}}_{11}$ modes. In the former, we show that large energy modulations $O$(100 keV). can be achieved while maintaining the overall electron beam quality. Further, we show that by using larger field strengths $O$(100 MV/m) the resulting transverse forces can be exploited with beam-matching conditions to filter arbitrary phases from the modulated electron bunch, leading to the production of $\ensuremath{\approx}100$ attosecond FWHM microbunches. Finally, we also investigate the application of the transverse dipole ${\mathrm{HE}}_{11}$ mode and find it suitable for supporting time-resolved electron beam measurements with sub-attosecond resolution. We expect the findings to be widely appealing to high-charge pump-probe experiments, metrology, and accelerator science.