Ultrawide-Angle Optical Elements With Enhanced Transmittance Obtained by a Half-Etched Moth-Eye Structure Coating on Infrared Substrates

With the traditional multilayers coating, it is difficult to achieve broadband and wide-angle antireflection optical properties simultaneously. As one of the most promising candidates for omnidirectional and broadband antireflection coating, the moth-eye structure has gained considerable attention in the past several decades because of its excellent optical performance and self-cleaning function. The challenges in the use of this technology, namely, its manufacturing cost and mechanical structural stability, limit its popularization. In this paper, a moth-eye structure surface combined with a residual layer of an identical material is proposed; the proposed composite structure can be formed by a one-step process of half-etched technology. For the design and optimization of the composite moth-eye structure, composite structures were compared by performing effective medium approximation (EMA) and rigorous coupled- wave analysis (RCWA). The structural parameters of the micro-nano surface were optimized to increase the mechanical stability considerably. The results showed that the optimized composite moth-eye structure has high transmittance for incident angles from 0 degrees to 80 degrees in the infrared spectrum. Furthermore, the transmission diffraction at high orders was suppressed efficiently at super-wide incident angles.