Attosecond Inner-Shell Lasing at Angstrom Wavelengths

• DOI: 10.48550/arxiv.2409.06914
• Publication Date: 2024-01-01
• Authors: Linker, Thomas M.; Halavanau, Aliaksei; Kroll, Thomas; Benediktovitch, A...; Zhang, Yu; Michine, Yurina; Chuchurka, Stasis; Abhari, Zain; Ronchetti, Daniele; Fransson, Thomas; Weninger, Clemens; Fuller, Franklin D.; Aquila, Andy; Alonso-Mori, Roberto; Boutet, Sebastien; Guetg, Marc W.; Marinelli, Agostino; Lutman, Alberto A.; Yabashi, Makina; Inoue, Ichiro; Osaka, Taito; Yamada, Jumpei; Inubushi, Yuichi; Yamaguchi, Gota; Hara, Toru; Babu, Ganguli; Salpekar, Devashish; Sayed, Farheen N.; Ajayan, Pulickel M.; Kern, Jan; Yano, Junko; Yachandra, Vittal K.; Kling, Matthias F.; Pellegrini, Claudio; Yoneda, Hitoki; Rohringer, Nina; Bergmann, Uwe
• Keywords: Atomic Physics (physics.atom-ph); FOS: Physical sciences; Physics - Optics; Physics - Atomic Physics; Optics (physics.optics)

Since the invention of the laser nonlinear effects such as filamentation, Rabi-cycling and collective emission have been explored in the optical regime leading to a wide range of scientific and industrial applications. X-ray free electron lasers (XFELs) have led to the extension of many optical techniques to X-rays for their advantages of angstrom scale spatial resolution and elemental specificity. One such example is XFEL driven population inversion of 1s core hole states resulting in inner-shell K$α$ (2p to 1s) X-ray lasing in elements ranging from neon to copper, which has been utilized for nonlinear spectroscopy and development of next generation X-ray laser sources. Here we show that strong lasing effects, similar to those observed in the optical regime, can occur at 1.5 to 2.1 angstrom wavelengths during high intensity (> ${10^{19}}$ W/cm${^{2}}$) XFEL driven inner-shell lasing and superfluorescence of copper and manganese. Depending on the temporal substructure of the XFEL pump pulses(containing ${~10^{6}}$ - ${10^{8}}$ photons) i, the resulting inner-shell X-ray laser pulses can exhibit strong spatial inhomogeneities as well as spectral splitting, inhomogeneities and broadening. Through 3D Maxwell Bloch theory we show that the observed spatial inhomogeneities result from X-ray filamentation, and that the spectral splitting and broadening is driven by Rabi cycling with sub-femtosecond periods. Our simulations indicate that these X-ray pulses can have pulse lengths of less than 100 attoseconds and coherence properties that open the door for quantum X-ray optics applications.