PUBLICATION: OPTICA

AUTHORS: Huang, NS; Deng, HX

Light with orbital angular momentum (OAM) provides new insights into a wide range of physical phenomena and has engendered advanced applications in various fields. Additionally, interest in X-ray OAM has been rapidly rising. We present a straightforward method to generate intense OAM beams from an X-ray free-electron laser oscillator (XFELO). The method leverages Bragg mirrors and longitudinal-transverse mode coupling to enable mode selection in a conventional XFELO configuration, thereby natively producing the fully coherent hard X-ray beams carrying OAM. Furthermore, simulation results demonstrate that fully coherent hard X-ray OAM beams at 1 MHz with a pulse energy of about 120 mu J can be generated without the optical mode converters. This simple approach could significantly advance the creation of X-ray OAM while stimulating the development of experimental methods. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.

LINKS: http://dx.doi.org/10.1364/OPTICA.428341