Fabrication of Nanostructures for Diffractive Optical Elements on Fused Silica Glass*

Diffractive optical lenses offer breakthrough features such as high-resolution, lightweight design, high-efficient performance and high-contrast focusing capabilities. These lenses can be employed in diverse fields including astronomy, free-space optical communications, spectroscopy, defense, and remote sensing. Traditionally, diffractive optics have exhibited a low transmission efficiency. In response, we have employed recent developments of photolithography techniques to fabricate diffractive nanostructures. In this study, we have fabricated multilevel Fresnel zone plates (FZP) and multilevel photon sieves (PS) on fused silica glass. Fused silica glass lenses offer large transparency range, low thermal expansion, and high resistance to optical damage, leading to great performance of these diffractive structures. As predicted from simulation data, the experimental results have exhibited 39% and 15.5% focusing efficiency for the 2-level FZP and 2-level PS, respectively, when compared with the amplitude-type FZP and PS of 10% and 5% focusing efficiencies, respectively. The outcome marks a significant advancement in the realm of high-resolution diffractive optics, enhancing the focusing efficiency that holds promise for various photonic applications.