Design and Simulation of Metalens Arrays for Enhanced MWIR Imaging Array Performance

Emerging flat optical components based on single layers of metamaterials and metasurfaces have introduced a new approach to microlens arrays. These components hold promise for seamless integration with narrow-bandgap semiconductor-based infrared focal plane arrays, aiming to increase operating temperatures and improve imaging sensitivity. This study focuses on the design and rigorous coupled-wave analysis-based simulation of dielectric-transmissive metalens arrays, specifically tailored to optimize the performance of mid-wavelength infrared imaging arrays. Both Si and Ge metalenses are modeled and compared to spherical lenses, with Ge requiring a smaller aspect ratio than Si due to its higher refractive index, simplifying fabrication. Simulations demonstrate that pixel-registered flat metalenses achieve focusing efficiencies comparable to conventional spherical lenses by reducing the pillar pitch to 1 µm, improving phase profile accuracy and minimizing high-order diffraction losses. These findings highlight the potential of customized metalenses to advance infrared imaging technology and provide practical insights for optimizing imaging array performance through integration with microlens arrays.