Multilayer Grating Optics for X-Ray Applications

Multilayer grating optics integrate periodic surface relief structures with Bragg-reflective thin-film stacks to disperse and tailor X-ray radiation with high resolution and efficiency. By combining the angular selectivity of multilayer coatings with the wavelength discrimination of diffraction gratings, this class of optics enables compact monochromators, spectrometers and beam-conditioning elements across the soft, tender and hard X-ray regimes. Fabrication approaches range from vacancy-controlled epitaxial growth of sub-50 nm period gratings to nanoimprint and ion-etch replication of blazed profiles. The interplay of grating blaze angle, groove density and multilayer d-spacing allows fine control of spectral bandwidth, higher-order suppression and peak reflectivity. Such devices are pivotal for synchrotron and free-electron laser beamlines, resonant inelastic X-ray scattering, space-borne telescopes and advanced laboratory instruments, offering global impact in materials science, chemistry, astrophysics and nanotechnology.

Research from Nature Portfolio

Researchers have demonstrated a maskless, wafer-scale fabrication route to produce multilayer gratings with sub-50 nm periods via vacancy epitaxy. The process yields uniform anisotropic surface patterns that are subsequently coated with alternating high- and low-Z layers, achieving ultra-large angular dispersion at soft X-ray energies near 90 eV and 270 eV. This scalable technique overcomes limitations of conventional lithography, paving the way for ultrahigh-resolution X-ray spectroscopy and compact, high-line-density dispersive optics for advanced light sources.

Multilayer Grating Optics for X-Ray Applications publication trend

The graph below shows the total number of articles in multilayer grating optics for x-ray applications across all publications each year (not limited to Nature Index journals).

Technical terms

Grating: An optical element with a periodic array of grooves that diffracts incident X-rays into discrete orders according to wavelength.

Blaze angle: The angle between individual groove facets and the grating surface, optimised to direct maximal diffracted intensity into a chosen order.

Multilayer coating: A stack of alternating thin films of contrasting refractive index that enhances reflectivity at specific X-ray energies via constructive Bragg interference.

Vacancy epitaxy: A fabrication technique where controlled vacancy diffusion during epitaxial growth induces periodic surface patterns without lithographic masks.

References

1. Realization of wafer-scale nanogratings with sub-50 nm period through vacancy epitaxy. Nature Communications (2019).
2. Spectral tailoring of nanoscale EUV and soft x-ray multilayer optics. Applied Physics Reviews (2017).
3. Advanced low blaze angle x-ray gratings via nanoimprint replication and plasma etch.. Optics Express (2023).
4. Optimized highly efficient multilayer-coated blazed gratings for the tender X-ray region.. Optics Express (2019).