Comparative analysis estimates for two-relief microstructure diffraction efficiency in the visible and dual-infrared ranges in the framework of scalar and rigorous diffraction theories

摘要

Subject of study. The diffraction efficiency of two-layer diffractive microstructures with two sawtooth internal reliefs is studied. Aim of study. The reliability of the results obtained using the scalar approximation is evaluated while considering the actual depths of two sawtooth reliefs (through the effective area method) when designing and calculating microstructures intended for operation in the dual-infrared range, including the mid- and farinfrared radiation subranges (3.4-11.4 mu;m). This is applicable to the selection of optimal pairs of optical materials, estimation of optimal relief depths, and assessment of achievable diffraction efficiency within a given range of angles of incidence of radiation on the microstructure for a chosen relative spatial period of the microstructure. Method. Combined mathematical modeling within the framework of scalar and rigorous diffraction theories is used. Main results. It is demonstrated that, in the dual-infrared range, additional electromagnetic optimization can yield results that significantly differ from those obtained by the effective area method only if the total depth of the reliefs exceeds the average wavelength of the working spectral range by more than an order of magnitude. Practical significance. The presented results offer the potential for a significant reduction in labor costs associated with the design of refractive-diffractive dual-infrared lenses. COPY; 2023 Optica Publishing Group