Design and fabrication of subwavelength antireflective microstructures on diamond surfaces

In this study, subwavelength microstructures on diamond have been investigated numerically and experimentally to attain high transmittance over a broad bandwidth in the mid-infrared(MIR) wavelength range of 8∼14 μm.A simulation model was established using FDTD software to theoretically investigate the influence of changes in microstructure parameters on the transmittance enhancement performance, and the relationship between microstructure parameters and transmittance was macroscopically demonstrated based on infrared spectral value distribution diagrams. Fabrication of square frustum microstructure arrays on diamond surfaces by airflow-assisted femtosecond laser in an air environment. The structure was created on a single work surface. The fabricated samples achieved full-wavelength transmittance enhancement in the MIR band from 8 μm to 14 μm, and the average transmittance was increased from 70.0% to 77.5%, of which the transmittance at 9 μm wavelength was increased by 8.3%. The experimental results illustrate that the fabricated microstructures have good transmittance enhancement performance.