Germanium and silicon-based nanohole LWIR metalens design and fabrication

Abstract. Thermal imaging, particularly LWIR imaging, has several applications in commercial and security systems. The fundamental problem with the development of metalens is the lack of appropriate materials for LWIR applications. The development of silicon metalens is hampered by the material’s own LWIR spectral band absorption, although silicon is the ideal material for lithography due to its widespread use in CMOS applications. In this study, metalens working on LWIR spectral band has been designed and fabricated using the highly suitable material germanium and low-cost silicon. The focusing and imaging capacity of two types of metasurfaces has been investigated, and a comparison of the results has been presented in the paper.