Higher order harmonics suppression in extreme ultraviolet and soft x-ray

Abstract

The extreme ultraviolet and soft x-ray sources are widely used in various domains. Suppressing higher order harmonics and improving spectral purity are significant. This paper describes a novel method of higher order harmonics suppression with single order diffraction gratings in extreme ultraviolet and soft x-ray. The principle of harmonic suppression with single order diffraction grating is described, and an extreme ultraviolet and soft x-ray non-harmonics grating monochromator is designed based on the single order diffraction grating. The performance is simulated by an optical design software. The emergent beams of a monochromator with different gratings are measured by a transmission grating spectrometer. The results show that the single order diffraction grating can suppress higher order harmonics effectively, and it is expected to be widely used in synchrotron radiation, diagnostics of laser induced plasma, and astrophysics.

High-efficiency V-shaped phase gratings to suppress high order diffractions

“…Based on the basic sinusoidal amplitude grating, twodimensional binary gratings utilizing the amplitude sinusoidal transmission function along one direction have been proposed. [14][15][16][17][18][19][20][21] The idea is that the average transmission effect along one direction is obtained by integrating the transmission function along the other directions. The average sinusoidal transmission function of binary gratings arises from complexshaped holes, such as sinusoidal or trapezoidal, 14,15 or the modulation of the hole positions.…”

“…The average sinusoidal transmission function of binary gratings arises from complexshaped holes, such as sinusoidal or trapezoidal, 14,15 or the modulation of the hole positions. [14][15][16][17][18][19][20][21] The absolute efficiency AIP Advances 9, 015308 (2019); doi: 10.1063/1. of the 1 st order diffraction is limited to 6.93% of the trapezoidal grating.…”

“…15 Moreover, the complex shapes or small gaps between holes increases the fabrication difficulty when using current nanofabrication techniques. In addition, modulated gratings [14][15][16][17][18][19][20][21] introduce background noise, which decreases the signal-to-noise ratio of the 1 st order diffraction. Therefore, we desire a grating that has a high 1 st order diffraction efficiency (not lower than the traditional sinusoidal grating) and large feature sizes (comparable to the traditional binary grating).…”