Blazed high-efficiency x-ray diffraction via transmission through arrays of nanometer-scale mirrors

Ralf K Heilmann,Minseung Ahn,Eric M Gullikson,Mark L Schattenburg

doi:10.1364/oe.16.008658

Abstract

Diffraction gratings are ubiquitous wavelength dispersive elements for photons as well as for subatomic particles, atoms, and large molecules. They serve as enabling devices for spectroscopy, microscopy, and interferometry in numerous applications across the physical sciences. Transmission gratings are required in applications that demand high alignment and figure error tolerances, low weight and size, or a straight-through zero-order beam. However, photons or particles are often strongly absorbed upon transmission, e.g., in the increasingly important extreme ultraviolet (EUV) and soft x-ray band, leading to low diffraction efficiency. We demonstrate the performance of a critical-angle transmission (CAT) grating in the EUV and soft x-ray band that for the first time combines the advantages of transmission gratings with the superior broadband efficiency of blazed reflection gratings via reflection from nanofabricated periodic arrays of atomically smooth nanometer-thin silicon mirrors at angles below the critical angle for total external reflection. The efficiency of the CAT grating design is not limited to photons, but also opens the door to new, sensitive, and compact experiments and applications in atom and neutron optics, as well as for the efficient diffraction of electrons, ions, or molecules.

Highlights

The soft x-ray to extreme ultraviolet (EUV) region of the electromagnetic spectrum, extending roughly from 0.5 to 50 nm in wavelength, contains many resonances for low to intermediate atomic number elements, and the so-called water window, rendering it a rich region for elemental identification and for the high-resolution imaging of carbon-containing objects [1]
The device layer contains the critical-angle transmission (CAT) grating bars that are carefully aligned to the {111} planes of the surface, and integrated supporting structures that consist of a coarse support mesh and a 10 mm × 12 mm release frame (see Fig. 2(a))
We have introduced and demonstrated a nearly absorption-free transmission grating design based on sub critical-angle reflection off of nanometer-scale mirrors that enables blazing and highly efficient broadband diffraction for EUV and soft x-ray photons

Summary

Introduction

The soft x-ray to EUV region of the electromagnetic spectrum, extending roughly from 0.5 to 50 nm in wavelength, contains many resonances for low to intermediate atomic number elements, and the so-called water window, rendering it a rich region for elemental identification and for the high-resolution imaging of carbon-containing objects [1]. Experiments in atom interferometry [4] are often limited by low flux, and efficient diffractive elements could drastically improve contrast and signal-to-noise ratios and sensitivity, independent of strong laseraccessible transitions Progress in this area could lead to advances in many fields, ranging from astronomy [5, 6], plasma [7, 8, 9] and atom [4] physics to the life and environmental sciences [10, 11], as well as in the areas of synchrotron and neutron [12, 13] optics and EUV lithography [14, 15]

Objectives

Results

Conclusion