Precision fabrication of diamond micro-optic elements with hybrid SiO2/Cr etching masks

Abstract

Diamond is opted for high-power optical systems due to excellent optical transparency, radiation, and thermal resistance, while the fabrication of micro-structures on diamond falls behind. Here we report a reliable fabrication method of diamond and fabricate a laminar grating with 2.90 μm period and 3.08 μm groove depth by directly laser writing(DLW) and reactive ions etching (RIE). We presented a micro-masks-less and high-temperature hybrid masks of diamond etching with dielectric SiO2 mask and Cr adhesive layer. We developed a statistical analysis method using Hough transform on SEM images, which could provide the quantitative results and monitor the variation of structures during fabrication process. The grating presents 28% diffraction efficiency in the 0th order and 9% in the ±1st order at 405 nm wavelength. The results of diffraction experiment are in close agreement with the rigorous coupled wave (RCWA) simulation.