The paradox of a free-electron laser without the laser

Phys.org  July 16, 2021 An international team of researchers (UK, the Netherlands) conducted a proof-of-principle experiment in the ultraviolet spectral range to demonstrate a new way of producing coherent light. In FELs the intensity of light is amplified by a feedback mechanism that locks the phases of individual radiators. This is achieved by passing a high energy electron beam through the undulator. As they wiggle through the undulator light emitted from the electrons bunch together causing amplification of the light and the increase in its coherence. If the electron bunch is shorter than the wavelength of the light produced by […]

Scientists propose novel self-modulation scheme in seeded free-electron lasers

Phys.org   March 11, 2021 Seeded free-electron lasers (FELs), which use the frequency up-conversion of an external seed laser to improve temporal coherence, are ideal for providing fully coherent soft x-ray pulses. However, it is difficult to operate seeded FELs at a high repetition rate due to the limitations of present state-of-the-art laser systems. Researchers in China have developed self-modulation method for enhancing laser-induced energy modulation, thereby significantly reducing the requirement of an external laser system. They have experimentally realized high harmonic generation in a seeded FEL using an unprecedentedly small external laser-induced energy modulation. The results pave a way for […]