Extreme-Ultraviolet Shaping and Imaging by High-Harmonic Generation from Nanostructured Silica

Coherent extreme-ultraviolet pulses from high-harmonic generation have ample applications in attosecond science, lensless imaging, and industrial metrology. However, tailoring complex spatial amplitude, phase, and polarization properties of extreme-ultraviolet pulses is made nontrivial by the lack of efficient optical elements. Here, we have overcome this limitation through nanoengineered solid samples, which enable direct control over amplitude and phase patterns of nonlinearly generated extreme-ultraviolet pulses. We demonstrate experimental configurations and emitting structures that yield spatially patterned beam profiles, increased conversion efficiencies, and tailored polarization states. Furthermore, we use the emitted patterns to reconstruct height profiles, probe the near-field confinement in nanostructures below the diffraction limit of the fundamental radiation, and to image complex structures through coherent diffractive emission from these structures. Our results pave the way for introducing sub-fundamental-wavelength resolution imaging, direct manipulation of beams through nanoengineered samples, and metrology of nanostructures into the extreme-ultraviolet spectral range.

Figure 1

(a) Experimental setup. (b),(c) Diffracted high harmonics generated inside the grating-structured rear surface. (d) Simulation of HHG diffraction from a near-field phase grating. (e) Height reconstruction, using the data from panel (c). (f),(g) Diffracted high harmonics generated by a phase-grating imprinted infrared pulse. (h) Simulation of HHG diffraction from a near-field amplitude grating. (i) Enhancement of HHG, total diffraction signal (red) compared to emission of a flat sample (black).

Figure 2

(a) AFM image of the structure. (b) Schematic of setup, for detecting zeroth and first-order diffraction. (c) Polarization-dependent HHG. (d) Polarization-dependent zeroth-order diffraction. (e) Polarization-dependent first-order diffraction. (f),(g) Simulation of the near-field of 800 nm, when polarized perpendicular and parallel to the grooves, respectively. (h),(i) Simulated polarization-dependent zeroth and first-order diffraction signals.

Figure 3

(a) Schematic of experimental setup. (b) Measured diffraction pattern of target in (a). (c) Simulated diffraction pattern of target in (a). (d) Measured diffraction pattern of an array of micron-sized pillars. (e) Reconstructed surface. (f) Microscope image of the array of micron-sized pillars.