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Metasurfaces, optics made from subwavelength-scale nanostructures, have been limited to millimeter-sizes by the scaling challenge of producing vast numbers of precisely engineered elements over a large area. In this study, we demonstrate an all-glass 100 mm diameter metasurface lens (metalens) comprising 18.7 billion nanostructures that operates in the visible spectrum with a fast f -number ( f /1.5, NA = 0.32) using deep-ultraviolet (DUV) projection lithography. Our work overcomes the exposure area constraints of lithography tools and demonstrates that large metasurfaces are commercially feasible. Additionally, we investigate the impact of various fabrication errors on the imaging quality of the metalens, several of which are specific to such large area metasurfaces. We demonstrate direct astronomical imaging of the Sun, the Moon, and emission nebulae at visible wavelengths and validate the robustness of such metasurfaces under extreme environmental thermal swings for space applications.

Various kinds of zinc oxide (ZnO) nanostructures, such as ZnO nanowires, ZnO nanobelts, ZnO nanosheets, and ZnO nanorods are promising building blocks for nanoscale systems. However, to precisely control the size, shape, and to make a controlled assembly of synthesized ZnO nanostructures are major difficulties in the development of bottom-up devices. To overcome the challenge regarding reproducibility and positioning, a new method is proposed, deep ultra-violet (DUV) direct photo-patterning, to create ZnO micro- and nanostructures. A sol-gel formulation sensitive to DUV light and based on zinc methacrylate precursor is developed, and the photoreactions of zinc methacrylate under DUV light are carefully investigated by in situ spectroscopic ellipsometry, in situ FTIR, and XPS analysis. Then, the sol-gel solution is used as a negative tone resist in DUV lithography to evaluate its performance in producing high-resolution patterns. The results indicate that small patterns from micro- to nanoscale can be obtained in a simple and direct way. [ABSTRACT FROM AUTHOR]

Metalenses promise potential for a paradigm shift of conventional optical devices. However, the aperture sizes of metalenses are usually bound within hundreds of micrometers by the commonly used fabrication methods, limiting their usage on practical optical devices like telescopes. Here, for the first time, we demonstrate a high-efficiency, single-lens, refractive metalens telescope. We developed a mass production-friendly workflow for fabricating wafer-scale (80 mm aperture) metalenses using deep-ultraviolet (DUV) photolithography. Our metalens works in the near-infrared region with nearly diffraction-limited focal spot sizes and a high peak focusing efficiency of 80.84% at 1450 nm experimentally. Based on the metalens, we built a single-lens telescope and acquired images of the lunar surface, revealing its geographical structures. We believe our demonstration of the metalens telescope proves the exciting potential lying in the metasurfaces and could bring new possibilities for areas involving large optical systems, including geosciences, planetary observation, and astrophysical science.

We demonstrate a highly efficient grating coupler with center wavelength near 1310 nm fabricated on a silicon-on-insulator (SoI) wafer by 248-nm deep ultraviolet lithography. One of the lowest reported losses of 2 dB is achieved using feature sizes of 200 nm and without other process enhancements, such as polysilicon. The higher efficiency is obtained through improved mode-matching based on a novel genetic algorithm, which utilizes two different etch depths. The 3-dB bandwidth is 50 nm, and the back-reflection to the waveguide is better than 20 dB. The result shows low-loss coupling between waveguides and single-mode fibers for 1310~nm applications suitable for mass production on the commonly used 220-nm SoI platform. [ABSTRACT FROM PUBLISHER]

Abstract: In this work we propose to fabricate nano-scale square lattice features using the principle of four wavefront interference employing a pyramidal prism. A UV laser of 266nm wavelength was used to pattern features on thinned positive tone resist AZ 7220 using single exposure technique. It was demonstrated that features with sub 500nm pitch size could be recorded using a pyramidal prism with edge angle of 30.4°. Holes with diameter around 187nm in square symmetry with pitch of 414nm were fabricated. The proposed setup is relatively simple, requiring minimum number of components. [Copyright &y& Elsevier]

Dedicated to the memory of Professor Sukant K. Tripathy The use of polymers based on biphenyl methacrylate as antireflective coatings (ARC) in lithographic applications is described. The optimum range of refractive index (n) and complex index (k) resulting in minimal reflectivity, as predicted by Prolith simulation, was 1.56 to 1.76 and 0.125 to 0.275, respectively, which corresponded to polymers containing 50 to 70 mol% of biphenyl methacrylate. ARCs from these polymers were formulated with a melamine crosslinker and a thermally activated catalyst. Optimal lithographic performance was obtained by baking the spin-coated films at 200°C for 90 seconds for crosslinker concentrations less than 7.5% as confirmed by lack of footing and scum at imaging layer/ARC interface. [ABSTRACT FROM AUTHOR]

Metalenses, planar lenses realized by placing subwavelength nanostructures that locally impart lenslike phase shifts to the incident light, are promising as a replacement for refractive optics for their ultrathin, lightweight, and tailorable characteristics, especially for applications where payload is of significant importance. However, the requirement of fabricating up to billions of subwavelength structures for centimeter-scale metalenses can constrain size-scalability and mass-production for large lenses. In this Letter, we demonstrate a centimeter-scale, all-glass metalens capable of focusing and imaging at visible wavelength, using deep-ultraviolet (DUV) projection stepper lithography. Here, we show size-scalability and potential for mass-production by fabricating 45 metalenses of 1 cm diameter on a 4 in. fused-silica wafer. The lenses show diffraction-limited focusing behavior for any homogeneously polarized incidence at visible wavelengths. The metalens' performance is quantified by the Strehl ratio and the modulation transfer function (MTF), which are then compared with commercial refractive spherical and aspherical singlet lenses of similar size and focal length. We further explore the imaging capabilities of our metalens using a color-pixel sCMOS camera and scanning-imaging techniques, demonstrating potential applications for virtual reality (VR) devices or biological imaging techniques.