Atmospheric hot embossing for producing glass nanolens arrays

• An atmospheric glass hot embossing method is proposed for decreasing the machine complexity and cost but increasing production efficiency. • Atmospheric hot embossing of glass nanolens arrays is realized by using sapphire nano-conical hole molds and a tailor-made heating module. • Algorithms for determining adhesion temperature and time boundaries between D-K9 glass and sapphire molds are proposed. • A prediction model is proposed for producing shape-controlled glass lens arrays of feature sizes in the nano scale. Nanolens arrays are critical components in advanced optical systems. Hot embossing technology demonstrates significant potential for high precision mass production of glass nanolens arrays. However, conventional hot embossing processes are implemented in vacuum or inert gas environment, which increase complexity and cost of the hot embossing device. To overcome this problem, this study proposes an atmospheric hot embossing method for fabricating high-quality glass nanolens arrays with the beam-splitting function by using sapphire nano-conical hole mold and a tailor-made heating module. Firstly, systematic glass adhesion tests were carried out for determining the adhesion temperature and time boundaries between D-K9 glass and sapphire molds. Hot embossing experiments under safe process parameters were then implemented for evaluating the influence of embossing temperature, force and hole diameters of sapphire mold on the shape of glass nanolens arrays. After that, a linear regression-based prediction model was established to control the nanolens height by adjusting the embossing temperatures, and four glass nanolens arrays with similar heights of ∼40 nm but different diameters were fabricated. Finally, diffraction efficiency of laser beams split by the shape-controlled glass nanolens arrays was simulated and measured. Furthermore, the influence of the heights and diameters of embossed glass nanolens arrays on the diffraction efficiency were analyzed.