Optical Fresnel zone plate flat lenses made entirely of colored photoresist through an i-line stepper

Light: Science & Applications volume  14, Article number: 43 (2025 ) Cite this article

Light manipulation and control are essential in various contemporary technologies, and as these technologies evolve, the demand for miniaturized optical components increases. Planar-lens technologies, such as metasurfaces and diffractive optical elements, have gained attention in recent years for their potential to dramatically reduce the thickness of traditional refractive optical systems. However, their fabrication, particularly for visible wavelengths, involves complex and costly processes, such as high-resolution lithography and dry-etching, which has limited their availability. In this study, we present a simplified method for fabricating visible Fresnel zone plate (FZP) planar lenses, a type of diffractive optical element, using an i-line stepper and a special photoresist (color resist) that only necessitates coating, exposure, and development, eliminating the need for etching or other post-processing steps. We fabricated visible FZP lens patterns using conventional photolithography equipment on 8-inch silica glass wafers, and demonstrated focusing of 550 nm light to a diameter of 1.1 μm with a focusing efficiency of 7.2%. Numerical simulations showed excellent agreement with experimental results, confirming the high precision and designability of our method. Our lenses were also able to image objects with features down to 1.1 μm, showcasing their potential for practical applications in imaging. Our method is a cost-effective, simple, and scalable solution for mass production of planar lenses and other optical components operating in the visible region. It enables the development of advanced, miniaturized optical systems to meet modern technology demand, making it a valuable contribution to optical component manufacturing.

Light manipulation and control are a cornerstone in various contemporary optical technologies. As such technologies mature and become more miniaturized, the size constraints for their constituent optical components inevitably become more stringent. An indispensable basic component in optical systems is the lens. Traditional lenses utilize refraction to gather or focus light, but as they require a certain thickness to function, their size often becomes a limiting factor in the miniaturization of optical systems. Thus, there has been increasing demand for a flat lens to overcome these constraints, the most prominent technology of which is the metasurface1,2,3,4,5,6,7. Metasurfaces are optical components consisting of sub-wavelength structures; they utilize the microscopic optical response of tailored sub-wavelength structures to modulate the amplitude and/or phase of the transmitted light. By carefully engineering the spatial distribution of such tailored structures, optical functions, such as light focusing, can be realized. Many recent papers have demonstrated the fabrication of such new flat lenses using metasurfaces, which are then often called metalens8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29.

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