Design and manufacturing of mid-infrared ultra-wide-angle antireflective composite micro-nano structure film

Traditional homogeneous optical thin films encounter difficulties in minimizing reflected energy at steep angles due to polarization separation. We drew inspiration from the natural 'moth-eye' structure and devised an innovative antireflective micro-nano interface, which provides a solution for the limitations faced by traditional optical films. This study designed an ultra-wide-angle antireflective composite micro-nano structure film by combining interference cancellation principles with the sub-wavelength effects of the 'moth-eye' micro-nano structure surface. Through meticulous analysis employing rigorous coupled-wave analysis, we elucidated the functionality of the micro-nano structure in ensuring effective antireflection at large angles. The simulation results demonstrate the superior performance of the composite micro-nano structure film, showcasing a remarkable 35% enhancement in antireflection efficiency compared to traditional films for oblique incidence angles (70-80 degrees). Moreover, it outperformed traditional film technologies for smaller incident angles (0-60 degrees). Furthermore, we experimentally fabricated a double-sided composite SiO2 micro-nano structure film layer on a sapphire substrate using displacement Talbot lithography and inductively coupled plasma technology. Our experimental results aligned with the simulation results, holding significant implications for advancing optical windows in mid-infrared devices.