Large aperture nano-colloidal lenses with dual-hole electrodes for reduced image distortion

Focus-tunable lenses without mechanical components are highly beneficial across various fields, including augmented reality (AR) devices, yet achieving a practical level of this technology is challenging. Recently, nano-colloidal lenses employing two-dimensional (2D) ZrP nanoparticles have been proposed as a simple and promising method to develop an electric-field-induced focus-tunable lens system. In this study, we investigate the relationship between the electrode design of nano-colloidal lenses and their performance, particularly in terms of focal length tunability and image distortion. In previous designs, increasing the lens size led to significant image distortion. To address this issue, we introduced a dual-hole electrode design and optimized the electrode size. This modification resulted in a wider focal length tunability and minimized image distortion, even in larger lenses. Additionally, we experimentally measured the refractive index variation and approximated the nanoparticle distribution to further optimize the lens's focal length and image distortion. Consequently, this study provides a comprehensive model for designing nano-colloidal lenses and electrodes, paving the way for their use in various applications.