Necklace-structured high-harmonic generation for low-divergence, soft x-ray harmonic combs with tunable line spacing

The extreme nonlinear optical process of high-harmonic generation (HHG) makes it possible to map the properties of a laser beam onto a radiating electron wave function and, in turn, onto the emitted x-ray light. Bright HHG beams typically emerge from a longitudinal phased distribution of atomic-scale quantum antennae. Here, we form a transverse necklace-shaped phased array of linearly polarized HHG emitters, where orbital angular momentum conservation allows us to tune the line spacing and divergence properties of extreme ultraviolet and soft x-ray high-harmonic combs. The on-axis HHG emission has extremely low divergence, well below that obtained when using Gaussian driving beams, which further decreases with harmonic order. This work provides a new degree of freedom for the design of harmonic combs—particularly in the soft x-ray regime, where very limited options are available. Such harmonic beams can enable more sensitive probes of the fastest correlated charge and spin dynamics in molecules, nanoparticles, and materials.The JILA team graciously acknowledges support from the Department of Energy BES Award No. DE-FG02-99ER14982 for the experimental implementation, a MURI grant from the Air Force Office of Scientific Research under Award No. FA9550-16-1-0121 for the mid-infrared laser soft x-ray research, and a National Science Foundation Physics Frontier Center grant PHY-1734006 for theory. N.J.B. acknowledges support from National Science FoundationGraduate Research Fellowships (grant no. DGE-1650115). Q.L.D.N. acknowledges support from National Science Foundation Graduate Research Fellowships (grant no. DGE-1144083). J.S.R., L.P., and C.H.-G. acknowledge support from Ministerio de Ciencia e Innovación (FIS2016-75652-Pand PID2019-106910GB-I00). This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement no. 851201). J.S.R., L.P., and C.H.-G. also acknowledge support from Junta de Castilla y León FEDER funds (project no. SA287P18). L.R. acknowledges support from Ministerio de Educación, Cultura y Deporte (FPU16/02591). C.H.-G. acknowledges Ministerio de Ciencia, Innovación, y Universidades for Ramón y Cajal contract (RYC-2017-22745), cofunded by the European Social Fund. L.R., J.S.R., L.P., and C.H.-G. thankfully acknowledge the computer resources at MareNostrum and the technical support provided by Barcelona Supercomputing Center (FI-2020-3-0013)

Temporal and spectral multiplexing for EUV multibeam ptychography with a high harmonic light source

We demonstrate temporally multiplexed multibeam ptychography implemented for the first time in the EUV, by using a high harmonic based light source. This allows for simultaneous imaging of different sample areas, or of the same area at different times or incidence angles. Furthermore, we show that this technique is compatible with wavelength multiplexing for multibeam spectroscopic imaging, taking full advantage of the temporal and spectral characteristics of high harmonic light sources. This technique enables increased data throughput using a simple experimental implementation and with high photon efficiency. &nbsp;</p

Supplementary document for High-fidelity ptychographic imaging of highly periodic structures enabled by vortex high harmonic beams - 6603827.pdf

supplementary documen