Fabrication of diamond transmission gratings for EUV-SXR applications using femtosecond laser

Chemical vapor deposition (CVD) diamond shows great potential as a material for optical devices such as gratings that can work effectively in extreme environments. However, traditional fabrication methods often encounter efficiency and heat management issues. Thick CVD diamond performs well in hard X-ray bands, yet its potential in the extreme ultraviolet (EUV) and soft X-ray (SXR) ranges remains underexplored. This study presents a novel method for producing large-area, substrate-free diamond transmission gratings for these bands through femtosecond laser direct writing and wet etching. We fabricated a 0.08 × 1 mm² transmission diamond grating with a 2 μm period, achieving a theoretical diffraction efficiency of 34.2 % in the EUV-SXR spectral ranges. This technique opens new possibilities for diamond optics design and production.