Suppression of higher diffraction orders in the extreme ultraviolet with a trapezoidal nano-mirror array

ABSTRACT

Higher diffraction orders from a grating introduce harmonic contamination in ‘monochromatic’ output beams processed by grating monochromators at synchrotron radiation facilities, resulting in imprecise calibration of optical elements and detectors. Suppressing these orders can be achieved with a quasi-random nano-hole array, but its fabrication can be a significant limiting factor for implementation. Here, an advanced type of grating is demonstrated that contains a periodic array of several hundred million trapezoidal nano-mirrors with a grazing-incidence reflection geometry that suppresses higher diffraction orders. Moreover, it reduces the difficulty of fabrication to the level of a traditional grating. It has great potential for harmonic suppression in synchrotron radiation, spectral diagnostics of plasmas, and astrophysics.